HAM Radio 3.2/Ham Radio Version 3.2 (Chestnut CD-ROMs)(1993).ISO/packet/replpkt/pktintro

Text File | 1990-12-07 | 103KB | 2,005 lines

INTRODUCTION TO PACKET RADIO - PART 1 - by Larry Kenney, WB9LOZ

Packet Radio is the latest major development to hit the world of
Amateur Radio.  If you haven't already been caught by the "packet
bug", you're probably wondering what it's all about and why so many
people are so excited about it.  Well, continue reading, because
you're about to find out.

Packet seems to offer something different from other facets of Amateur
Radio, yet it can be used for everything from a local QSO to a DX
contact 2500 miles away (on 2 meters!), for electronic mail, message
transmission, emergency communications, or just plain tinkering in the
world of digital communications.  It presents a new challenge for
those tired of the QRM on the low bands, a new mode for those already
on FM, and a better, faster means of message handling for those on
RTTY.  Packet is for the rag chewer, the traffic handler, the
experimenter, and the casual operator.

A ham can get involved very easily with relatively small out-of-
pocket expenses.  All you need is a 2-meter transceiver, a computer or
terminal, and a TNC.  You probably already have the two meter rig and
a computer of some kind, so all you need to buy is the TNC, which
costs just over $100. The TNC is the Terminal Node Controller, the
little black box that's wired between the computer and the radio.  It
acts very much like a modem when connecting a computer to the phone
lines.  It converts the data from the computer into AFSK tones for
transmission and changes the tones received by the radio into data for
the computer.  It's a simple matter of wiring up a plug and a couple
jacks to become fully operational.

Packet is communications between people either direct or indirect.
You can work keyboard to keyboard or use electronic mailboxes or
bulletin board systems to leave messages.  Due to the error checking
by the TNC, all of it is error free, too.  (That is, as error free as
the person at the keyboard types it.)  As the data is received it's
continuously checked for errors, and it isn't accepted unless it's
correct. You don't miss the information if it has errors, however,
because the information is resent again.  I'll go into how this is
accomplished in a later part of this series.

The data that is to be transmitted is collected in the TNC and sent as
bursts, or packets, of information; hence the name.  Each packet has
the callsign or address of who it's going to, who it's coming from and
the route between the two stations included, along with the data and
error checking.  Since up to 256 characters can be included in each
packet, more than three lines of text can be sent in a matter of a
couple seconds. There is plenty of time between packets for several
stations to be using the same frequency at the same time.

If all of this sounds confusing, don't let it bother you, because that
little black box, the TNC, does everything for you automatically.
Packet might seem very confusing at first, but in a day or two you're
in there with the best of them.   In this series I'll be telling you
more about packet--how you get on the air, how to use it to your best
advantage, and ways to improve your operation.   We'll talk about that
little black box, the TNC, and tell you about all its inner-most
secrets.  We'll discuss mailboxes, bulletin board systems, and the
packet networks that allow you to work stations hundreds of miles away
using just a low powered rig on 2 meters, 220 or 450.  The world of
packet radio awaits you!

- - - -


INTRODUCTION TO PACKET RADIO - PART 2 - by Larry Kenney, WB9LOZ

In the first part of this series we told you, in general terms, what
packet radio was all about...what it is, its uses, the equipment used
and, generally, how its transmitted.  Now we're going to tell you how
to get on the air, make a QSO, and become familiar with your packet
station.  Whether you're new to packet, having just received a new
TNC, have been involved for just a short time, or are one of the "old
timers" with four or five years of experience, this series should help
all of you.  Even if you don't yet own a TNC, you should keep this
article handy for future use.  I'll bet you'll be joining us soon!

The equipment needed to get on the air is a VHF transciver, a computer
or terminal, and a TNC - the terminal node controller - the little
black box we talked about in part 1.  (There is packet activity on HF,
but VHF is where all the action is.  It's the best place to start out
in packet.)  The TNC contains a modem and is equivalent to the modem
used to connect your computer to the phone lines, except that it also
contains special software that's specially designed for ham radio
packet use.

When you buy a TNC and take it out of the box, you'll find cables
supplied for connecting it to the radio, but you'll have to attach the
appropriate mic and speaker jack connectors for the radio you're going
to use.  You also have to furnish the cable that connects the TNC to
your computer or terminal.  In most cases, the standard RS-232 port is
used between the TNC and computer, however this varies with the type
of computer and TNC used. The operating manuals supplied with the TNCs
have a good write up on the various computers and the cabling needed.
I would advise that you read the introduction and set up procedures
for your particular TNC very carefully. Most companies have supplied
excellent manuals, and you usually can figure out all of your set up
problems from the the information supplied in the manual.

Once you have everything wired and connected together, turn on the
computer, load a terminal program (anything used for a phone modem
will work well for packet) and get into receive mode.  Now turn on the
radio and make sure the volume is turned up about a quarter turn
(about the "10 or 11 o'clock" position) and make sure the squelch is
set.  It should be at the point where the background noise disappers,
just as it would be set for a voice QSO.  Next, turn on the TNC.  You
should get a "greeting" or sign on message showing the manufacturer's
name, software version, etc.  If you see a bunch of gibberish, such as
&tf$d.#ssan>m, it means that the data rate of the TNC and computer are
not the same.  This data rate is better known as the baud rate. The
baud rate of the TNC has to match the baud rate used by your computer
terminal program and is easily adjusted.  Check you TNC manual for
this procedure, as it varies from TNC to TNC.  If you don't see a
"greeting" or the gibberish, check your cables and connections.  Make
sure that you have everything connected properly, that the right wires
are on the right pins, etc.

Now we need to explain the three levels of communicating you can do
from the keyboard.  First, you can communicate with your computer for
setting up the terminal program; second, you can communicate with the
TNC; and third, you can communicate with the radio.  It's very
important that you know which level you're in when working packet.  I
can't help you much with the computer level, since that varies with
manufacturer, model and the terminal program you're using, but once
you get the terminal program ready to receive data, you're ready to
talk to the TNC.

First, do a "control C" (press the CNTL and the letter C
simultaneously); this puts the TNC in COMMAND mode, the level where
you communicate directly with the TNC from the keyboard.  You should
see "cmd:" on your screen.

Enter:
MYCALL - - - -

with your callsign in place of the dashed lines, such as MYCALL WB9LOZ
followed by a carriage return (CR).  All commands are followed by a
(CR). This sets into the TNC memory the call that you're going to use
on the air. Now if you type MYCALL (CR), it should respond with your
call.  If it does, you've proven that the computer to TNC linkup is
working fine.  If you do not see anything on the screen when you type,
blindly enter the following: ECHO ON (CR).  If you see two of
everything that you type, such as MMYYCCAALLLL, enter ECHO OFF (CR).

You're now ready to go on the air!  Tune the receiver to any odd
numbered frequency between 144.91 and 145.09 that has some activity on
it and set the rig up for simplex operation.  Enter MONITOR ON (CR),
then watch the screen.  You should soon be seeing the packets that are
being sent over the air by other stations.  If you don't see anything
in a minute or two, try tuning to another frequency.  Watch for
callsigns with a * next to it, such as  W6PW-1*, WA6RDH-1*, or
WB6SDS-2*.  Callsigns with an asterick indicate that you're copying
the packet from that station, as it's being repeated, or digipeated,
by a packet repeater.  Jot down the call.

In packet, you can have up to 16 different stations on the air at the
same time using the same callsign.  That's where the numbers in the
callsign come into play.  The calls W6PW, W6PW-1, W6PW-2, W6PW-3,
W6PW-4 and W6PW-5 are all individual stations operating under the same
station license.  A callsign without a number is the same as -0. The
numbers are used to differentiate between the various stations.

Now, before you try to make your first QSO with someone else, you
should check out your equipment to make sure it's set up properly.  To
do that, you can CONNECT to yourself.  Note one of the callsigns you
jotted down a minute ago.  Make sure your radio is still tuned to the
frequency where you heard that call, then enter the following:

C - - - - V - - - - (CR)

where the first dashed lines are YOUR callsign and the second dashed
lines are the call of the station you jotted down.  The C means
CONNECT and the V means VIA.  C WB9LOZ V W6PW-1 means connect to
WB9LOZ via W6PW-1.  You should soon see "*** CONNECTED TO (your call)"
on the screen.  You have now entered the third level of
communications, called CONVERSE mode, and this is where you
communicate from the keyboard to the radio.  Anything you type on the
keyboard will be transmitted over the air as a packet every time you
hit a (CR).  If you enter "Test" (CR) you should see "Test" a second
time on the screen, as it's transmitted, then digipeated and sent back
to you. In this case you'll only be talking to yourself via another
station, but it's a good way to check to make sure your system is
working properly.  If that works, hit a CONTROL C.  This puts you back
into COMMAND mode where you talk to the TNC again.  Enter D (CR).
This will disconnect you from the other station, and you'll see
"DISCONNECTED" on the screen.

Now you're ready to talk to someone else!  Watch for a familiar call
on the screen while monitoring or note calls you see frequently.  Be
sure to note whether or not a digipeater is being used by watching for
the *.  If you see WB9LOZ > WA6DDM, W6PW-1*, for example, you're
receiving the packets from W6PW-1.  If you do not see an asterick, you
are copying the station direct.  When the station you want to contact
is finished with his QSO, enter:

C - - - -   or

C - - - -  V  - - - - (depending on whether or not a digipeater is
                          needed)

followed by (CR).    You should get a "*** CONNECTED TO ..." on the
screen, which means you're in converse mode, and your first QSO with
someone else is underway!  Anything you type now will be sent to the
other station, and anything he types will be sent to you.  When you're
finished, be sure to do a CONTROL C to get back into command mode,
then enter  D  to disconnect from the other station.

You're on the way now to lots of packet fun and adventure!  If you are
still having problems at this point, contact a friend that has some
experience on packet and ask for help.  The initial set up of the
computer, TNC and radio is probably the biggest stumbling block in
packet.  Any experienced packeteer will be happy to help you get
through this process to get you on the air.

- - - -


INTRODUCTION TO PACKET RADIO - PART 3 - by Larry Kenney, WB9LOZ

In Part 2 I talked about how to get on the air and make your first
QSO. Now let's take a look at some of the commands that are available
in your TNC to help improve your station operation.

TNC COMMANDS: The TNC, or Terminal Node Controller, that "little black
box" we've talked about in the past, has more than 100 different
commands for you to use.  You're able to customize your packet
operating with these commands and turn on and off various features as
you wish.  Not all TNCs are exactly alike, but all have pretty much
the same functions. I'll be using the commands used by the TNC2 and
clones in my examples.

We covered a few of the commands previously: CONTROL C for entering
command mode, MYCALL, MONITOR, CONNECT, and DISCONNECT.  Now let's
discuss a few that can change the way your station functions.

  ECHO: This command tells the TNC whether or not it should send what
you type back to the monitor screen.  If you don't see anything when
you type, set ECHO to ON.  IIff yyoouu sseeee ddoouubbllee, like that,
set ECHO to OFF.  This setting will depend on how your particular
computer system functions.

  CONV (converse mode): Your TNC will automatically switch to this
mode when you connect with someone, but you can also do it by entering
CONV (CR) at the Cmd: prompt.  When in converse mode, anything you
type will be transmitted via the path you set with UNPROTO.  (See the
next paragraph.) Anyone in monitor mode will be able to read what you
transmit.  Packets in converse mode are sent only once and are not
acknowledged, so there is no guarantee that they'll get through.  This
mode is used frequently for sending CQ's.

  UNPROTO: This command designates the path used when in converse
mode. The default is CQ, but you can enter a series of digipeaters if
you wish, or a specific group or club name.  Some examples:

       CQ v WB6SDS-2,W6SG-1,AJ7L      SFARC v W6PW-1,W6PW-4

Remember, you have to change UNPROTO for use on different frequencies,
unless you leave it set simply to "CQ".

  FRACK: This determines how long your TNC will wait for an
acknowledgement before resending a packet.  It shouldn't be set too
short, or you simply clutter up the frequency, yet it shouldn't be too
long, or you'll spend too much time waiting.  I use FRACK set to 7,
and have found that to be an overall good value.

  DWAIT: Used to avoid collisions, DWAIT is the number of time units
the TNC will wait after last hearing data on the channel before it
transmits. I have DWAIT set to 16, and have found that to work well.

  PACLEN: Determines the number of characters in your packets, ranging
from 1 to 256.  The more characters you send per packet, the longer it
takes to transmit the information and the greater your chances are of
noise, interference or another station wiping it out. I've found a
PACLEN of 80, which is the length of one line, to be a good  value.
When working a station nearby, PACLEN can be increased.  When working
a distant station, it should be decreased.

  RETRY: Your TNC will retransmit a packet if it doesn't receive an
acknowledgement from the station you're working.  RETRY indicates the
number of times the TNC will try to get the packet through before
giving up and disconnecting.  This can be set from 1 to 15, but I've
found 8 to 10 to work well.  Less than that causes an unnecessary
disconnect if the channel happens to be busy, but more than that
clutters up the channel.

The following TNC commands affect the monitoring mode and what you see
on the screen:

  MONITOR: This must be ON for you to monitor anything.  When ON, you
see packets from other stations on the frequency you're tuned to.
What packets you see is determined by other commands from the list
below.  If MONITOR is OFF, you see only packets sent to you while
you're connected to another station.

  MALL: If MALL is ON, you receive packets from stations that are
connected to other stations, as well as packets sent in unproto
(unconnected) mode. This should be ON for "reading the mail". If MALL
is OFF, you receive only packets sent in unproto mode by other
stations.

  MCOM: If ON, you see connect <C>, disconnect <D>, acknowledge <UA>
and busy <DM> frames in addition to information packets.  If OFF, only
information packets are seen.

  MCON: If ON, you see packets from other stations while you're
connected to someone else.  This can get very confusing, but is useful
when your path is bad and you want to see if your packets are being
digipeated okay.  If OFF, the monitoring of other stations is stopped
when you're connected to another station.

  MRPT: If ON, you see a display of all the stations used as
digipeaters along with the station originating the packet and the
destination station. If OFF, you see only the originating and
destination stations.  For example, if you have MRPT ON, you might see
a transmission such as this:

  K9AT>WB6QVU,W6PW-5*: I'll be leaving for the meeting at about 7:30.

If MRPT was OFF, the same transmission would look like this:

  K9AT>WB6QVU: I'll be leaving for the meeting at about 7:30.

In the first case, you can see that the W6PW-5 digipeater was being
used. The asterick indicates which station you were hearing the packet
from.  In the second case you have no idea if digipeaters are being
used or what station you were receiving.

  HEADERLN: If you have this turned ON, the header of each packet is
printed on a separate line from the text.  If OFF, both the header and
packet text are printed on the same line.

  MSTAMP:  Monitored packets have the date and the time the packet was
received if MSTAMP is ON.  If it's OFF, the date/time stamp is not
shown.

I run my station with all of these commands, except MCON, turned ON so
that I can really see what's happening on the frequency I'm
monitoring.  Try various combinations of these commands and then
decide on the combination you like best for your station.

- - - -


INTRODUCTION TO PACKET RADIO - PART 4 - by Larry Kenney, WB9LOZ

USING DIGIPEATERS AND NODES:

DIGIPEATERS:

Digipeater is the term we use to describe a packet radio digital
repeater. Unlike the FM voice repeaters, most digipeaters operate on
simplex and do not receive and transmit simultaneously.  They receive
the digital information, temporarily store it and then turn around
and retransmit it.

Your TNC will allow you to enter up to eight digipeaters in your
connect sequence, but using more than 3 usually means long waits, lots
of repeated packets, and frequent disconnects, due to noise and other
signals encount- ered on the frequency.

When entering the list of digipeaters in your connect sequence, you
must make sure that you enter them in the exact order that your signal
will use them.  You must separate the calls by commas, without any
spaces, and the EXACT callsigns must be used, including the SSID, if
any. That means you need to know what digipeaters are out there before
you begin randomly trying to connect to someone.  Turn MONITOR ON and
watch for the paths that other stations are using.

Here are some examples of proper connect sequences:
C W6PW-3 v W6PW-1
C N6ZYX v WA6FSP-1,WB6LPZ-1
C W6ABY-4 v K6MYX,N2WLP-2,AB6XO

The "v" means via.  In the first example the sequence shown means:

Connectto W6PW-3 via W6PW-1.

Something to remember when using digipeaters is the difference between
making a connection and sending information packets.  If the path
isn't all that good, you might be able to get a connect request
through, but will have a difficult time with packets after that.  The
connect request is short so it has much less of a chance of being
destroyed by noise or collisions than a packet containing information.
Keeping information packets short can help keep retries down when the
path is less than ideal.

NODES:

Net/Rom, TheNet, G8BPQ packet switch and KA-Node are names that refer
to a device called a packet node, another means of connecting to other
packet stations.  Later on in this series you'll find a complete
review of node operation, but for now we'll cover the basics so that
you can begin using the node network.  The difference you should note
here is that you connect to a node rather than using it in a connect
path as you do with a digi- peater.

First, you need to determine what nodes are located close to you.  You
can do this by monitoring and watching for an ID or by watching to see
what other stations in your area are using.  You'll note that most
nodes have an alias ID in addition to its callsign.  Once you
determine the callsign or alias of a local node, you connect to it the
same way as you connect to any other packet station.  You may use
either the callsign or the alias to make the connection.  For example,
the node I operate has the alias ID of SF and the callsign of
WB9LOZ-2, so you could connect to it using "C SF" or "C WB9LOZ-2".
Either one will work.

When you connect to a node, your TNC automatically switches to
converse mode, just like when you connect to any packet station.
Anything you now type is sent to the node as a packet, and the node
acknowledges each packet back to your TNC.  For the remainder of your
connection your TNC works only with this one node.

To use the node network to connect to another local station, you
simply enter a connect request as though you were connecting direct
from your TNC, such as "C WB9LOZ".  You do this, however, while you
ARE STILL CONNECTED TO THE NODE.  The node will then retransmit your
connect request and you'll receive one of two responses:  "Connected
to (callsign)" or "Failure with (callsign)".  Once you're connected
you hold your QSO just as if you had connected direct or via a
digipeater.  When you're finished, go to command mode on your TNC
(Control C) and enter "D" (CR) and you will be discon- nected from the
node and the station you were working.

(NOTE: If the node you're using is a G8BPQ packet switch, it might
have several frequency ports.  You'll have to enter a port number
between the C and the callsign in your connect request to indicate the
frequency you want to use, such as "C 2 WB9LOZ".  Enter "PORTS" for a
port list.)

When you're connected to a node enter "NODES" <CR> and you'll receive
a list of other nodes that you can reach on the network from the node
you're using.  You'll note that the node list will vary in length and
in the calls listed as you move from frequency to frequency, since all
frequencies are not linked together.  The list gives both an alias ID
and a callsign for each node.  The alias ID often gives you a hint as
to where the node is located, but not always.  To find out for sure
where a node is located you'll need to get a copy of the descriptive
node listings that are available on most packet bulletin board
systems.  These complete lists give the alias, callsign, location,
frequency and other information on each node in the network.

To connect to a station in another area using the node network you
first must determine which node is closest to the station you want to
work.  For demonstration purposes, let's say we want to connect to
N6ZYX.  He's told you he uses the the W6AMT-3 node, so you check the
node list and see that SFO3:W6AMT-3 is listed.  WHILE STILL CONNECTED
TO YOUR LOCAL NODE you first connect to the distant node by sending a
normal connect request, in this case "C W6AMT-3".  Your TNC will send
this as a packet to your local node and your local node will
acknowledge it.  The network will then go to work for you and find the
best path between your local node and the one you're trying to reach.
You might have to be a little patient here, as it sometimes takes a
few minutes for the connection to be completed.  You'll then see one
of two responses: "Connected to W6AMT-3"  OR  "Failure with W6AMT-3".
If it can't connect for some reason, try again later.  It could be
that W6AMT-3 is temporarily off the air or the path has decayed and is
no longer available.  We're going to be positive here and say we
received the first option.

Once you're connected to W6AMT-3, enter "C N6XYZ".  Again, your TNC
will send this as a packet to your local node and the local node will
acknowl- edge it and send it down the path to W6AMT-3.  W6AMT-3 will
then attempt to connect to N6XYZ.  Here again you'll get one of the
two responses: "Connected to N6XYZ"  OR  "Failure with N6XYZ".  If you
get connected, you hold your QSO just as you normally would, but
there's one BIG difference -- your TNC is receiving acknowledgements
from your local node, and N6XYZ is receiving acknowledgements from
W6AMT-3.  The acknowledgements do not have to travel the entire
distance between the two end stations.  Each node in the path handles
the acknowledgement with the next node in line.  Because of this,
retries are greatly reduced, and your packets get through much faster.

When you're finished with the QSO, you disconnect in the normal
manner. Go to Command Mode on your TNC and enter "D" <CR>.  The entire
path will then disconnect automatically for you.

Nodes offer a variety of other features besides allowing you to
connect to other stations, and we'll look at those in parts 10 and 11
of this series.

- - - -


INTRODUCTION TO PACKET RADIO - PART 5 - by Larry Kenney, WB9LOZ

USING A PACKET BULLETIN BOARD SYSTEM: This information is based on
W0RLI software, so the instructions might vary slightly for users of
AA4RE, WA7MBL, MSYS or other type systems. Use the H - HELP command on
your BBS if some of these commands do not work as described here.

You connect to a bulletin board system (BBS) exactly the same way as
you connect any other station.  Once connected, you'll receive a
welcoming message, some information on the BBS and instructions.  This
information will vary from system to system.  Read the information and
instructions carefully.  The first time you connect you'll receive a
request to enter your name, QTH, zip code and home BBS for the system
user file.  On some systems, the software will not let you do anything
else until you have entered this information.  When you receive the
welcoming message, you'll note that the last line ends with a >.  This
is known as the prompt, and is where you enter the command you want
performed next.

You enter your name using the letter N followed by a space and then
your first name, such as: N Larry.  Your QTH is entered using NQ
followed by a space then your full city name and two letter state
abbreviation, such as: NQ San Francisco, CA.  You enter your zip code
with NZ followed by a space and your five-digit zip.  Your "home BBS"
is the system that you plan to use regularly and want all of your
personal messages delivered to.  Make sure that it's a full service
BBS, not a personal mailbox, since only full service systems are
included in the message forwarding network.  You enter your home BBS
by typing NH followed by a space and then the call of the BBS, such as
NH W6PW. (Note: SSIDs are not used with BBS operation except for when
making the connection.  The BBS software ignores all SSIDs.)  This
user information is stored at the local BBS and is also sent to a
central data bank known as the "White Pages Directory".  The
information can be accessed by anyone.  System operators (sysops) use
it for determining your home BBS when forwarding messages, and you can
use it to find the name, QTH and home BBS of your friends.  How to use
the "White Pages" will be discussed in part 9 of this series.

When checking in to a BBS for the first time, you should become
familiar with the commands available to you.  Each BBS or mailbox is a
little different from the next, so read the introduction carefully and
follow the directions.  If you don't know what to do next, enter H for
the HELP instructions.  Make note of the command letters, enter only
one command at a time, and make sure you enter them correctly.
Computers are not very forgiving and expect things to be entered in
proper form.  Take your time, check out the features that the BBS
offers and enjoy yourself.  There's no need to feel rushed or
intimidated.  If you get to a point where you don't know what to do
next, don't give up and disconnect, enter H again for further HELP.
That's what it's there for!  I suggest that you make a printer copy of
the complete help file so that you have it available as a reference
when using the BBS.

Now let's go through the basic procedures you should follow when
checking into a BBS.  If there are personal messages addressed to your
call, the BBS will list them for you following the welcome message.
Note the message numbers.  At the > prompt, the first thing you should
always do is list the new messages, by entering L.  The BBS program
updates the user file each time you check in, logging the latest
message number.  The next time you check in, only new messages that
have been received by the system will be included in your list.  The
first time you'll receive all of them, since they're all new to you.
This list can be very long, as many systems have more than 200 active
messages on line.  When you receive the list, note the numbers of the
messages you're interested in reading.

Next, read the messages you're interested in.  You do this by entering
R XXXX, where the Xs represent the message number, such as R 4521.
Note that there is a space between the command and the number.  It's
best to have your buffer or printer turned on when reading messages,
because they're apt to come in faster than you're able to read them.
You should have a means of saving them for reading later after you've
disconnected. If there were messages addressed to you, you should
erase or "kill" them once you've read them.  You can do this with the
"KM" command, which means "Kill Mine".  This command will erase all
messages that are addressed to you that have been read.  You can also
kill each message individually by entering K XXXX, where the X's are
the message number.

Once you've read all the messages you're interested in, you have
several options.  You can look back at old messages, send messages to
other stations, see what's available in the files section, download a
file, upload a file, check the list of stations that have recently
checked in to the BBS or stations that have been heard on frequency,
monitor other frequencies used by the BBS, use the gateway feature (if
available), check the status of the BBS tasks, or a variety of other
things.

We look at the BBS commands in detail next.

- - - -


INTRODUCTION TO PACKET RADIO - PART 6-A   by Larry Kenney, WB9LOZ

In the previous section we discussed the basics of using a packet bulletin
board system.  Now let's look at the BBS commands in more detail.  This
information is based on the W0RLI software so some of the commands might
vary slightly on systems using different software, such as REBBS, MSYS,
WA7MBL, etc.  Use H (HELP) on your BBS if you find that a command doesn't
work as described here.

LIST COMMAND: The first thing you should do when logging on to a BBS is to
use the LIST command.  There are many variations available, but L, by
itself, is the one used most often.
     L (List) - Lists all new messages, except other users' personal
         messages, that have been entered since you last logged in.
If you want to list specific messages, you may use one of the following
variations of the L command:
     LM  - (List Mine) - Lists all messages addressed to you.
     Lx  - Lists all messages of the type designated by 'x'. Example:
           LB will list all bulletins.
     L # - Lists messages back to and including number #. Example:
           L 4050 will list all messages, except personal messages to
           others, from the latest one back to #4050.
     LL #- Lists the last # messages.  Example: LL 20 lists the last 20
           messages received at the BBS, excluding other's personal
           messages.
     L 1 - Lists ALL non-personal messages.
     L> callsign - Lists all messages TO callsign indicated. Example:
           L> N6XYZ
     L< callsign - Lists all messages FROM callsign indicated. Example:
           L< N6XYZ
     L@ designator - Lists all messages that have that "designator" in
           the @ BBS column of the message header.  Example: L@ ALLCAN
           will list all messages with ALLCAN in the @ BBS column.

READ COMMAND:  To read a message, you enter R followed by a space then the
message number.  Example: To read message 5723, you'd enter: R 5723. You
also have the option of using the RH command, which will give you all of
the forwarding headers in detail, rather than just giving you the path.
Example: To read message 5723 with the full headers, you'd enter RH 5723.
There is one other version of the READ command, and that's RM.  Entering RM
by itself will give you all of the messages addressed to you that have not
yet been read.

ERASING MESSAGES:  Once you have read a personal message, please erase it.
The sysop will appreciate your help in clearing up "dead" messages. You use
the K - KILL command to do this.  You can enter K #, such as K 5723, which
will erase that particular message, or you can enter KM, which will erase
all of the personal messages you have read.  If you use the KM command, the
BBS will list the message numbers for you as they're killed.

THE "S" COMMAND:  S (Send) and (Status):  The letter S by itself will give
you a reading of the BBS status on W0RLI systems, showing the callsigns of
stations using the system, the time they connected, the ports and tasks
they're using, etc.  It also shows information on the messages waiting for
users and those waiting to be forwarded to other bulletin board systems.
S, by itself, on other systems will either prompt you for further
information on sending a message, or it will give you an "illegal command"
error prompt.

To use the "S" command for sending a message it must be further defined.
There are three types of messages found on a packet bulletin board system:
Personal, Bulletin, and Traffic.
    "SP" is used for sending a personal message to one other station,
    "SB" for sending a bulletin, and
    "ST" for sending a message that's going to be handled by the
         National Traffic System.
You're able to send a message to one particular person, to everyone on the
local BBS, to everyone at every BBS in Northern California, in Southern
California, in the entire state, or all across the entire country.  It all
depends on your addressing.

At the BBS prompt you enter the appropriate command (SP, SB, or ST)
followed by a space and then the addressee.  The addressee can be a
callsign or it can be something of a general nature, such as ALL, QST,
ARES, etc.  Examples:  SP WB9LOZ    SB ALL    SB SALE
All commands, of course, must be followed by a <CR>.

If you wish to send the message to someone at another BBS, you have to
indicate the call of the other BBS and the two letter abbreviation of the
state it's located in following the call of the addressee.  For example, to
send a message to N5PQ, who uses the W5XYZ BBS in Texas, you would enter:
   SP N5PQ @ W5XYZ.TX
The BBS call and the state abbreviation are separated by a period. This is
the bare minimum required for delivery of messages going out of state.  A
more complete system of addressing is available.  It's helpful in directing
your messages to stations in the U.S more quickly and is required for
messages going to stations outside of the U.S.  It's called hierarchical
addressing, and its covered in detail in the next part of this series.

To send a general message or bulletin to more than just the local BBS, you
need to use a designator in place of the BBS call.  The designator
indicates the area where you want the message distributed.  In northern
California,
    ALLCAN indicates that you want the message sent to all Northern
           California BBSs, which includes all of them from Santa Cruz,
           Gilroy, and Fresno northward.
    ALLCAS is used to send a message to all BBSs in the southern part
           of the state.
    ALLCA  is used for sending a message to EVERY BBS in the state.
    ALLUSW is used for distribution to CA, AZ, NV, OR, WA and ID.
    USA    is the designator to use for sending a message to EVERY BBS
           IN THE USA.  Extreme care should be used when using the USA
           designator.  Please make sure that the subject matter is of
           interest to packet users everywhere and please keep the
           message as short as possible.  "For Sale" messages should
           NOT be sent with the @ USA designator.  The National HF
           Packet Network is somewhat fragile, due to varying band
           conditions, so unnecessary traffic can keep more important
           traffic from getting through.

Here are a few examples of how you would correctly address a bulletin-type
message for general distribution:

   SB ALL @ ALLCAN   SB SALE @ ALLCA   SB QST @ ALLCAS   SB AMSAT @ USA

If you have traffic for the National Traffic System, you must use a special
format.  NTS messages are entered as ST ZIPCODE @ NTSXX, where the XX is
the two-letter state abbreviation.  Examples:

               ST 03452 @ NTSNH    ST 60626 @ NTSIL

When you have the address line of your message complete, you enter a
carriage return (<CR>).  You'll then receive a prompt asking for the
SUBJECT or TITLE of the message.  Enter a brief description of what the
message will be about, followed by a <CR>.  Next, you'll be asked to enter
the TEXT of the message.  When entering the text, you should insert
carriage returns at the end of each line, as if you were typing a letter.
A normal line has a maximum of 80 characters, so when you have 70 to 75
characters typed, enter a carriage return and continue on the next line.
This will prevent words from wrapping around to the next line and the
program inserting an unnecessary blank line in the text.  After you have
completed the text, you end the message with a CONTROL Z. (You send a
CONTROL Z by holding down both the CONTROL key and the Z key simultan-
eously.)  You must follow the CONTROL Z with a carriage return.  (Some
systems will also allow you to use /ex to end a message.)  When you receive
the BBS prompt, you'll know that the message has been accepted by the
system.




INTRODUCTION TO PACKET - Part 6-B   By Larry Kenney, WB9LOZ

FILE DIRECTORY COMMANDS:
    W (What) - Entering W, by itself, gives you a list of the directories
available on the BBS along with an associated letter for each directory,
called the directory ID.
    Wd  - Gives a list of the files in the directory indicated by d. The
"d" is the directory ID you obtain with the W command.

   D (Download) - Used for reading files from a directory.  Must be used
with a directory ID and filename using the following form:  Dd filename
The "d", again, is the directory ID and the filename must be entered
exactly as listed in the directory.   Example:    DG FCCEXAM.INF

    U (Upload) - Used for uploading (sending) a file to the BBS.  The
command must be used with a directory ID, followed by the filename you're
assigning to the file, using the form: Ud filename.  The d indicates the ID
of the directory where you want to enter the file.  Filenames can have up
to 8 characters preceding the dot and 3 characters following the dot.
Example: UM FLEAMKT.INF would upload a file named FLEAMKT.INF into the
directory with the M ID.  The BBS program will not allow you to upload a
file with a filename that already exists, and some directories are set by
your local sysop for downloading only.

GENERAL MISCELLANEOUS COMMANDS:
     I (Info) - Gives you details on the hardware, software and RF
facilities of the BBS you're using, or on some systems, a page of upcoming
events, helpful hints, or other useful information.

     J - Displays a listing of stations that were heard by the BBS or that
connected to the BBS.  Must be used with a port identifier, such as JA, JB,
etc.  J by itself will list the port IDs for you.

     M (Monitor) - Used for monitoring the activity on another port of the
BBS. Must be used with a port identifier, such as MA, MB, etc. M by itself
will list the port IDs.  (Not available on all systems.)

     B (Bye) - When you're finished using the BBS, you enter a B to
disconnect.

HELP DOCUMENT: Every BBS has help available for the user.  Simply enter an
H and follow the directions given.  In most cases, an H followed by a space
and then the letter of the command you want help on will give you the
specific information you need.  For example, if you wanted to know more
about the Download command, you would enter H D at the prompt.

There are other commands available that are specific to the particular
software being used.  Check your local BBS for a complete list of the
commands available to you.

- - - -



INTRODUCTION TO PACKET - PART 7 - by Larry Kenney, WB9LOZ

W0RLI, N6VV, and VE3GYQ have devised a scheme called HIERARCHICAL
ADDRESSING.  With hierarchical routing designators we have an
opportunity to improve traffic routing.  No longer will a missing call
in a BBS forwarding file cause a message to remain unforwarded, sysops
will no longer have to burn the midnight oil trying to keep their
forward files up to date, and messages will move much more directly
toward their destination.

The format for hierarchical routing is:

   addressee @ BBScall.#local area.state-province.country.continent.

It might look complicated, but it's not.  First, note that each
section of the format is separated by a period.  Codes used for the
continents and countries are standards, now accepted throughout the
world.  You should be able to find a list of them in the file section
of your BBS.  State and province codes are the recognized
two-character codes established by the American and Canadian Post
Offices.  These may be found in the Callbook, your phone directory, or
any zip code listing.  Don't guess on the state and province code if
you aren't sure what it is, and make sure you use only the two-letter
abbreviation.  You could send the message to the wrong state or
province or keep it from being forwarded altogether.  The code for the
local area is optional, since most of you have no idea what code is
being used in upper New York state or in Iowa City, IA.  If you do
know it, please use it, since it will help get the message closer to
where it's going.  The code for Northern California is #NOCAL, and the
code for Southern California is #SOCAL.  You should use the
appropriate one in the signature line at the end of each message you
send.  For messages going outside of the US or Canada, the local area
is again optional and the state-province is not used.

Using the hierarchical format, here are some routing examples:

    WB9LOZ @ W6PW.#NOCAL.CA.USA.NA
    WB6LYI @ K6VE.#SOCAL.CA.USA.NA
    KC3XC @ N4QQ.MD.USA.NA
    VE3XYZ @ VE3RPT.ON.CAN.NA
    JA1ABC @ JA1KSO.#42.JPN.AS
    VK4AHD @ AX4BBS.AUS.OC

You'll note that the local area code is preceded by the octothorpe
(now, how's that for a $5 word?), better known as the number or pound
sign.  The reason is that the Japanese network, and possibly other
areas, use routing numbers for the local area, which could get
confused with zip and postal codes. Using the # on all local area
codes will eliminate forwarding problems.

We need to emphasize two very important points: hierarchical
addressing DOES NOT indicate a forwarding PATH, and ONLY ONE BBS call
should be included in the address.  A list of BBS calls separated by
periods will not get your message to its destination.  In fact, it can
cause your message to loop between BBSs and your message probably
won't be delivered. The addressing scheme is said to be one area
inside another area.  Using my hierarchical address as an example,
WB9LOZ @ W6PW.#NOCAL.CA.USA.NA, here's how you would describe the
address: "WB9LOZ at W6PW which is in Northern California which is in
California which is in the USA which is in North America".

There are several BBS programs that implement hierarchical addressing
now, including the W0RLI, WA7MBL, AA4RE, MSYS and WD6CMU software.
Check the ID block you receive when you log into your BBS.  If it has
an H in it, such as [RLI-11.11-CH$] or [4RE-02.10-HM$], your system
supports it.

USING THE HIERARCHICAL ADDRESS: This next section explains how the BBS
software uses the hierarchical addressing scheme.  We first have to
understand how the software goes about matching items in the "@ BBS"
address with items in the forward file.  For an example, let's say
that we send a message to Tom, W3IWI, who operates his own BBS and is
located near Baltimore, Maryland.  We would enter:

     SP W3IWI @ W3IWI.MD.USA.NA

If the only entries in the forward file are California BBSs plus a
list of state abbreviations, let's see how the message would be
forwarded.  The first thing the software does is attempt to find a
match between the items in the forward file and the left-most item in
the address field.  In our case, it would not find W3IWI.  If there
isn't a match, it then moves to the next section to the right.  It
would find MD and that match would allow the message to be forwarded.
If it had found the call W3IWI, that entry would take precedence
(because it is more left in the field than MD) and would of course
also ensure delivery.

Here are some comments from the ones who devised the hierarchical
addressing:

"There is another added benefit to this scheme.  It involves
Gatewaying between the BBS world and other networks, such as TCP/IP
via SMTP.  Much of the pioneer work in setting up the gatewaying
protocols has been done by NN2Z, N3EUA, and PA0GRI, amongst others.
The W0RLI BBS package allows for the forwarding of mail between the
BBS world and the SMTP world.  Of note is the fact that the WA7MBL
package has allowed such message exporting and importing for some time
now.  This means that we can take advantage of the the TCP/IP
host-names and their domain or hierarchal format for forwarding. Thus
it is possible to send mail from the BBS to VE3BTZ as
[e-mail] or from SMTP to [e-mail] and
not have any ambiguity.

"The authors hope that this paper will serve as a starting place for
improved message routing by means of implicit routing.  Low-level
(VHF) BBSs need only maintain state or province or country codes for
distant BBSs, and route such traffic to their nearest HF Gateway.  In
turn, the HF station routes it to the desired state, where the
receiving Gateway station would have a detailed list of the BBSs it
serves."

Comments from W0RLI, N6VV and VE3GYQ.

- - - -


INTRODUCTION TO PACKET RADIO - PART 8 - by Larry Kenney, WB9LOZ

This part of the series discusses, in detail, the various parts of the
packet message.  The following is an example of what you see when
listing messages on a BBS.  On some systems the information is
displayed in a different order, but the same information is given.

 MSG# STAT SIZE TO     FROM   @ BBS  DATE/TIME SUBJECT

 4723 P    1084 WD5TLQ WA6XYZ N5SLE  0604/1240 Software working great!

 4721 BI    771 PACKET WB9LOZ ALLUSW 0604/1154 INTRODUCTION TO PACKET

 4717 BF   2387 EXAMS  W6NLG  ALLCAN 0604/1020 FCC Exams: June - Dec.

 4715 T     275 94114  W1AAR         0604/0959 QTC San Francisco
                                                415-821

 4712 BF    918 ALL    N6ZYX  ALLCAN 0604/0845 9600 BAUD DEMONSTRATION

The MESSAGE NUMBER is assigned by the BBS program when the message is
received and it cannot be changed.  The numbers are assigned
sequentially.

The STATUS of the message includes several different bits of
information. The first letter of the STATUS indicates the TYPE of
message: B for Bulletin, P for Personal, or T for Traffic for the
National Traffic System. Bulletins are messages of general interest to
all users, and are available to be read by everyone using the system.
Personal messages are listed only for the sender and the addressee,
and they're the only ones that can read them.  (Anyone in monitor mode
could see a personal message as it's being sent over the air, of
course.)  The list above would have to have been requested by WA6XYZ
since it lists an outgoing personal message.  Traffic messages, type
T, are messages used for handling traffic on the National Traffic
System.  (Refer to part 12 of this series for information on NTS.)

STATUS also shows if the message has been read, has already been
forwarded to all designated stations, is in the process of being
forwarded, or is an "old" message.  You might see one of these
letters: Y - yes, it has been read,  F - it has been forwarded,  I -
it's in the process of being forwarded right now on another port, or O
- the message has been on the BBS long enough to become an "old"
message.  "Old" can be anywhere from 2 days for an NTS message to 3
weeks for bulletins.  The time frame for each message type is
specified by the local sysop.  The "O" is mainly used to catch the
attention of the sysop.

The SIZE indicates the combined total of characters, including
punctuation in the message.

TO is who the message is addressed to or it can be a message category.
The call of the addressee is entered for a personal message, and for
bulletins it could be ALL, EBARC, USERS, etc. TO is also used to
categorize bulletins by particular topics.  You might find a message
addressed TO AMSAT, TO PACKET or TO SALE, when it is actually a
message about AMSAT, about PACKET or about equipment for SALE.  For
NTS messages TO is the zip code of the addressee.

FROM shows the callsign of the station originating the message.

@ BBS is used if you want a message to be forwarded to someone at
another BBS or for general distribution using a forwarding designator.
In the list shown above, the personal message would automatically be
forwarded to WD5TLQ at the N5SLE BBS.  By entering a special
designator, such as ALLCAN, in the "@ BBS" column a message can be
forwarded to specific areas.  (See Part 6 and 7 of this series for
details on addressing messages and using forwarding designators.)

Next is the DATE and TIME when the message was received at the BBS
you're using.  (If the message was originated at another BBS, the date
and time when the message was originally entered will be shown in the
forwarding headers, as explained below, and at the top of the message
when you read it.)  Keep in mind that the date and time indicated can
be either local time or GMT (Zulu time) depending on the time used by
the BBS.

The SUBJECT (or TITLE) is a short line telling what the message is all
about.  It should be brief, but informative.  For bulletin type
messages, this is the information that determines whether or not a
person is going to read your message when he sees it in the message
list.

The parts of the message mentioned so far are all included in the
header of the message, and are seen when listing messages.  The
hierarchical address and the message ID are not shown in the normal
listing.  On some systems, such as those using W0RLI software,
entering a semicolon after the list command will give you this
information.  (Example:  LL 15 ;)

If a message has been forwarded from another BBS, forwarding headers
are added at the top of the actual message text.  This is information
added by each BBS that was used to get the message from its
origination point to the destination.  Each BBS adds one line showing
the time the message was received by that particular BBS, its call
sign, and usually the QTH, zip 8code, and message number.  Other
information is often added, at the discretion of the sysop there.  If
you use the RH command, rather than just R, when reading a message,
such as RH 7823, you'll receive complete headers.  With just the R,
headers are reduced to a list of the BBS callsigns.  Complete headers
are useful if you want details on the path the message took to reach
you or how long it took to be forwarded from system to system from the
source to destination.

The TEXT of the message contains the information you want to convey to
the reader.  It can be of any length.  When entering a message into a
BBS, use carriage returns at the ends of your lines, as if you were
using a typewriter.  The normal screen width is 80 characters, so you
should enter a carriage return prior to the 80th character on each
line.  Don't allow the automatic wrapping of lines to occur.  A
message entered without carriage returns is very difficult to read, as
words are cut at improper points, lines vary drastically in length,
and blank lines are often inserted.

You should include your name, call and packet address at the end of
the text so that the person reading your message will be able to send
a return message to you if he or she wishes to do so.

You complete the text with either a Control-Z or these three
characters: the "slash" (/) plus the letters "EX".  These characters
must be on a line by themselves.  On some systems only the Control-Z
will work.  This tells the system that you've finished entering the
message.

Messages that are going to be forwarded to several BBSs or across a
long distance should be limited in size.  Extremely long messages can
tie up the forwarding system unnecessarily, so users are advised to
break up long messages into parts, keeping them to a length of 2 - 3 K
each.

- - - - -


INTRODUCTION TO PACKET RADIO - Part 9 - by Larry Kenney, WB9LOZ

In this part we're going to look at the White Pages.  No, not your
local telephone directory, but the packet radio directory known as the
"White Pages".  You help supply the information for "WP", and you can
also use it to find the home BBS, QTH and zip code of your friends on
packet.

"White Pages" was initially designed by Eric Williams, WD6CMU, of
Richmond, California.  Hank Oredson, W0RLI, later added a WP database
to his packet bulletin board software.  It's a database of packet
users showing their name, home BBS, QTH and zip code.  It's updated
and queried by packet message, allowing stations from all over the
world to take advantage of it. As users enter their name, home BBS,
QTH and zip code into the BBS user file, the software automatically
assembles a message once a day containing all of the latest user
information and sends it to AD8I in Ohio, now the national White Pages
Server.  Systems in Northern California also exchange this
information.  As a result, you can easily find the name, home BBS, QTH
and zip code of other packet stations on packet all across the country
using the White Pages database.

If your BBS is operating with its own WP database, you may make
inquiries of it using the "I" command.  Simply enter I followed by the
callsign you'd like information about.  If you wanted information on
WB9LOZ, for example, you would enter: I WB9LOZ

Information from the WD6CMU or AD8I White Pages is obtained by sending
a message to "WP @ WD6CMU.CA" or "WP @ AD8I.OH".  Since the messages
are read and answered by the WP software, not a person, you must use
the correct format:  <callsign> QTH?  You may include as many requests
as you wish in one message, but each request must be on a separate
line. The last line of the message should be: DE <your_callsign> @
<Home_BBS> so that the response is returned to you at your home BBS.
If the return address line is not given, the WP program will attempt
to determine the originating station and BBS from the message headers.
If the requested information is not available from the WP database,
the return message will tell you so.

Here's an example of a message sent to the WD6CMU or AD8I White Pages
database:

(Your BBS prompt) W6BBS> SP WP @ WD6CMU.CA    (SP WP @ AD8I.OH would
                                               be used for the ADSI
                                               database)

Enter subject of message: Query
Enter text:
K9AT QTH?
WA6DDM QTH?
KC3XC QTH?
K3AKK QTH?
DE N6XYZ @ W6BBS
(Control Z)

Capital and lower case letters may both be used within the message.

Just like all other packet messages, messages addressed to WP are
forwarded from BBS to BBS toward their destination.  If a BBS
operating with the W0RLI WP Server handles a query message, it will
respond with any pertinent information that it has available.  As a
result, you might receive more than one response to your WP query.

The WP program also collects data from any WP responses it sees, as
well as from the headers of every message that passes through.  The
information on each call in a WP database is usually deleted in 60 to
90 days if it's not updated.  This is determined by each local sysop.

It is important to note here that you should choose ONE BBS as your
home BBS, the one where you want all of your messages delivered.
Always enter that callsign when you are asked to enter your home BBS,
even if you are using another system at the time.  When a message
arrives at the BBS destination given in the "@ BBS" column, some of
the latest software will check the White Pages information to make
sure that the message has been delivered to the right place.  If it
finds that a different BBS is listed as the addressee's home BBS, it
will insert that BBS callsign in the message and send it on its way.
If you enter different home BBS calls on several BBSs, your mail could
easily end up being sent from BBS to BBS and never reach you.

If you move or change your home BBS, you should then make sure that
you update the information for your call in the White Pages database.
Use the NH, NQ and NZ commands to update the information.  Making sure
that the information in the White Pages is correct will help to get
your messages delivered to the correct BBS.

- - - -


INTRODUCTION TO PACKET RADIO - PART 10 - By Larry Kenney, WB9LOZ

In this and the next part of the series we're going to take an in
depth look at the packet node network.  In part 4 of this series we
explained how to use the network for connecting to another station.
Now we'll look at the other features a node offers.

A packet node, in most cases, is still set up for digipeater
operation, so you can still use it as a regular digipeater, but for
most of your connections you'll want to use the node features.  When
using a string of digipeaters, your packets have to reach their
destination parity correct, and the receiving TNC has to return an
acknowledgement (ack) to your TNC for each packet cycle to be
completed.  As you add more digipeaters to the string, the chances of
this happening become less and less.  Other stations on the frequency
and noise can be the cause of many retries.  When using a node,
however, your packets no longer have to reach their destination before
acknowledgements are returned to your TNC.  Each node acknowledges
your packet as its sent along the way toward its destination.

Using the packet node network can make your operating time on packet
more enjoyable and it can greatly expand the area that you can reach.
The network of NET/ROM, TheNet, G8BPQ and KAM nodes is expanding very
quickly and now covers most of the country.  New nodes are showing up
almost daily. Thanks to all of these stations and the interconnecting
links, you can now connect to stations in many far distant places
using a low powered 2 meter rig.  Some nodes are set up for
cross-banding, and with the introduction of nodes on 10 meter FM,
there's the possibility of working a station just about anywhere.

If you've been monitoring lately, you might have seen the nodes in
action. You might have wondered why they were sending all of those
weird symbols like @fx/<~|.  What you're seeing is the nodes
communicating with each other and updating their node lists.  You also
might have noted callsigns with high numbered SSIDs, such as
WB9LOZ-14, WA6DDM-15, W6PW-12, etc.  The nodes change the SSID of all
stations so that the packets sent via the network are not the same as
those sent directly.  If you were to use a node to connect to another
station in the local area, there's the possibility of your packets
being received by this station both from you directly and from the
node. If the call through the node wasn't changed, the TNCs involved
would be totally confused as it would appear that two stations were
connecting using the same callsign.  The node automatically changes
the SSID using the formula 15-N, where N is your usual SSID.  A call
with -0 becomes -15, a -1 becomes -14, -2 becomes -13, etc.

The node network is very simple to use.  As explained in part 4, to
use the node network, you first connect to a local node.  It should be
one where you can connect direct with good signal strength.  Once
you've connected, you then have several options -- connect to another
station within range of the node, connect to another node, connect to
an associated BBS, obtain a list of the nodes that are available, or
check route and user status.  On NET/ROM and TheNet nodes you can also
answer or call CQ.

There are several commands available on your local node.  All have
CONNECT, NODES, ROUTES and USERS, and depending on the type of node
you're using, you might also find the BBS, BYE, CQ, INFO, PARMS or
PORTS commands available.

THE PACKET NODE COMMANDS:

CONNECT: The CONNECT command (which can be abbreviated as C) is used
just like you use the CONNECT command with your TNC.  To connect to
another local station using the node, simply enter C followed by the
callsign.  To connect to another node you can use either the callsign
or the alias.  For example, you can connect to W6AMT or you can
connect to the alias SFO. Either one will work.

There's a special consideration when making connections from a node
using the G8BPQ Packet Switch software.  Since these nodes are capable
of having several different frequencies connected to the one node, you
have to indicate which frequency port you want to make your connection
on.  The PORTS command, abbreviated P, will give you a list of the
ports available, such as this:

    SF:WB9LOZ-2} Ports:

        1 223.52 MHz
        2 144.99 MHz
        3 443.15 MHz

You then insert the port number between the C and the callsign, such
as C 2 W6RFN, to indicate which frequency you want to use, in this
case the port 2 frequency of 144.99 MHz.

NODES: The NODES command (which can be abbreviated as N) will give you
a listing of other nodes that can be worked from the node you're
connected to.  It lists both the alias and the callsign of each node
it knows about. The list you'll find on each node will vary in length
and will contain different callsigns since all of the frequencies are
not linked.

(continued with more on the NODES command and other commands in part 11)

- - - -


INTRODUCTION TO PACKET - Part 11 - by Larry Kenney, WB9LOZ

THE NODE NETWORK - continued

The NODES command has another feature that gives you a simple way to
find out if another node is accessible and, if it is, the best route
to use to reach it. It's easy to make a quick check of the route
quality to any other node.  All you need to do is enter N followed by
either the alias or callsign of the node that you want to reach, such
as:

      N FRESNO    or    N W6ZFN-2

You'll receive a report showing up to three routes to the node you
asked about, how good these routes are and how up to date the
information is. If there is no information available, you will receive
either "Not found" or the complete node list, depending on the type of
node or switch you're using.

Let's take a look at a typical report you would receive after entering
N FRESNO.  If you were connected to a NET/ROM or TheNet node the
report would look like this:

    SFW:W6PW-1} Routes to: FRESNO:W6ZFN-2
      105 6 0 WB9LOZ-2
      78 6 0 WW6L-1
      61 5 0 WA8DRZ-7

If you were connected to a G8BPQ packet switch you would see one less
column in the report and it would look like this:

    SF:WB9LOZ-2} Routes to: FRESNO:W6ZFN-2
    > 126 6 W6PW-10
      61 3 WW6L-1
      60 4 W6PW-1

Each line is a route to the node you asked about.  The symbol >
indicates a route that's in use.  The first number is the quality of
the route.  255 is the best possible quality and means a direct
connect via hard wire to a coexisting node at the same site; zero is
the worst, and means that the route is locked out.  192 is about the
best over the air quality you'll find, and it usually means that the
node is only one hop away.  If you see a quality of less than 80,
you'll probably have a difficult time getting any information through
via that route.  The second number is the obsolescence count.  This
number is a 6 when the information for this route is less than an hour
old.  For each hour that an update on the route is not received, this
number is decreased by one.  A 5 means the information is an hour old,
a 4 means that it's two hours old, and so on. The next number, shown
only on NET/ROM and TheNet nodes, indicates the type of port.  A 0 is
an HDLC port; a 1 is an RS-232 port.  You don't need to pay any
attention to this figure.  The callsign is that of the neighboring
node that's next in line on the route.  Digipeaters are shown if any
are used to reach this neighboring node.

This quick check on a node that you want to reach can save you a lot
of time.  You'll know immediately whether or not the node is
available, and if it is, how good the available routes are to it.  You
then won't have to spend time trying to connect to a node that isn't
available or is of poor quality.

If you find that there's a decent route to the node or switch you want
to reach, it's normally best to let the network make the connection
for you. Simply enter a connect to the alias or callsign you want
rather than connecting to each individual node along the route
yourself.

If a route exists but the quality is not very good, you might want to
connect to the neighboring node shown for the best route, then do
another quality check, repeating this procedure until you find a route
with decent quality.  You can actually get through to some distant
nodes using this method if you have the time and patience to work on
it.

ROUTES: The ROUTES command (abbreviated as R) will give you a list of
the direct routes available from the node you're using to other nodes.
These are the nodes seen directly by the node you're using.  The
quality of each route is shown along with the obsolescence count, as
explained above.  Any route marked with an exclamation point (!) means
that the route values have been entered manually by the owner of the
node and usually means that the route is not reliable for regular use.

USERS: The USERS command (which can be abbreviated as U) will show you
the calls of all the stations using the node you're connected to.
There are five descriptions used by the node to describe how users are
connected:

   UPLINK: The station indicated is connected directly to the node.

   DOWNLINK: The node has made a connection from the first station to
   the second station.  Example:  DOWNLINK (K9AT-15 N6UWK)  would mean
      that the node connected to N6UWK at the request of K9AT.

   CIRCUIT: Indicates that the station has connected from another
      node. It shows the alias and call of the other node prior to the
      user's call.  Example:  Circuit (SFW:W6PW-1 WA6DDM) would mean
      that WA6DDM is using this node, but he connected to it from the
      SFW:W6PW-1 node.

   CQ: See "CQ" below.

   HOST: The user is connected directly from the node terminal. This
      is seen when the owner of the node is a user, or the BBS
      associated with the node is using it to forward messages.

CQ COMMAND: The CQ command (which cannot be abbreviated) is used for
calling CQ, and it also can be used for replying to the CQ of another
station.  The CQ command is available only in the latest version of
NET/ROM and TheNet.

Using the CQ Command:  The CQ command is used to transmit a short text
message from a node, and is also used to enable stations that receive
the transmission to connect to the station that originated it.  The
command is entered as: CQ [textmessage] The "textmessage" is optional
and can be any string up to 77 characters long (blanks and punctuation
are allowed).  In response to a CQ command, the node transmits the
specified textmessage in "unproto" mode, using the callsign of the
originating user with a translated SSID as the source and "CQ" as the
destination.  For example, if user station W6XYZ connects to a node
and issues the command: "CQ Anybody around tonight?", the node would
then transmit "W6XYZ-15>CQ: Anybody around tonight?"

After making the transmission in response to the CQ command, the node
"arms" a mechanism to permit other stations to reply to the CQ.  A
station wishing to reply may do so simply by connecting to the
originating call- sign shown in the CQ transmission (W6XYZ-15 in the
example above).  A CQ command remains "armed" to accept replies for 15
minutes, or until the originating user issues another command or
disconnects from the node.

Any station connected to a node may determine if there are any other
stations awaiting a reply to a CQ by issuing a USERS command.  An
"armed" CQ channel appears in the USERS display as:

    (Circuit, Host, or Uplink) <~~> CQ(usercall).

The station may reply to such a pending CQ by issuing a CONNECT to the
user callsign specified in the CQ(...) portion of the USERS
display--it is not necessary for the station to disconnect from the
node and reconnect.

Here's what a typical transmission would look like: (* = entered by
user)

*  cmd: C KA6YZS-1
   cmd: *** Connected to KA6YZS-1
*  USERS
   501SJC:KA6YZS-1} NET/ROM 1.3 (669)
   Uplink(WB9LOZ)
   Uplink(K1HTV-1)            <~~>  CQ(K1HTV-14)
   Circuit(LAS:K7WS-1 W1XYZ)  <~~>  CQ(W1XYZ-15)
   Uplink(N4HY)
*  CONNECT W1XYZ-15
   501SJC:KA6YZS-1} Connected to W1XYZ
*  Hello!  This is George in San Jose
   Hi George!  Thanks for answering my CQ.   etc.

Users of the CQ command are cautioned to be patient in waiting for a
response.  Your CQ will remain "armed" for 15 minutes, and will be
visible to any user who issues a USERS command at the node during that
time.  Wait at least five minutes before issuing another CQ to give
other stations a chance to reply to your first one!

BBS: The BBS command is available on nodes using the G8BPQ software
where an associated packet bulletin board system is operational.
Entering BBS will connect you to the associated BBS.

BYE: The BYE command is available on G8BPQ nodes and is used for
disconnecting from the node.  It does the same thing as disconnecting.

IDENT: The IDENT command, found on NET/ROM nodes, will give you the
identification of the node you're using.

INFO: The INFO command, found on TheNet and G8BPQ nodes, will give you
information about the node, usually the alias, callsign and location.

PARMS: The PARMS (Parameters) command, found on NET/ROM nodes, is for
the owner's use in determining how his station is working.

- - -


INTRODUCTION TO PACKET RADIO - PART 12 - by Larry Kenney, WB9LOZ

The National Traffic System, known as NTS, is the ARRL sponsored
Amateur Radio message handling network.  Packet radio is now playing a
very important part in the network, so let's take a look at the system
and give you some tips on handling NTS traffic by packet.

Handling third party traffic is the oldest tradition in amateur radio.
Nationwide, the National Traffic System has hundreds of local and
section nets meeting daily in order to facilitate the delivery and
origination of such messages.  More and more of this traffic is being
originated, relayed, and delivered on packet.  If you enjoy traffic
handling, you can easily get involved in NTS via packet.  If you're on
packet but know nothing about NTS, this part of the series will get
you off to a good start.  At the end you'll also find some references
for further information on NTS.

Local packet BBSs have to be checked daily for traffic that needs to
be delivered or relayed.  When you check into your local BBS, enter
the LT command, meaning "List Traffic".  The BBS will sort and display
a list of all NTS traffic awaiting delivery.  It'll look similar to
this example:

 MSG# STAT SIZE TO     FROM   @BBS   DATE/TIME SUBJECT

 7893 T     486 60625  KB6ZYZ NTSIL  1227/0712 QTC1 CHICAGO, IL
                                     312-267

 7802 T     320 06234  K6TP   NTSCT  1227/0655 QTC1 NEW HAVEN, CT

 7854 T     588 93432  KA4YEA        1227/0625 QTC1 CRESTON, CA 93432

 7839 T     412 94114  KK3K          1227/0311 QTC1 SAN FRANCISCO
                                     415-821

 7781 T     298 94015  W1KPL         1226/2356 QTC1 DALY CITY, CA
                                     415-992


You might see traffic that is being relayed by your local BBS to some
other part of the country as well as traffic for your local area. The
"Subject" or "Title" column of the listing will show the destination
of the traffic. If you see a message that is within your local area,
help out and deliver it.

RECEIVING A MESSAGE: To take a message off of the Bulletin Board for
telephone delivery, or for relay to a local NTS net, enter R followed
by the message number.  Using the list above, R 7839 would send you
the message from KK3K for San Francisco.  You'll find the message in a
special NTS RADIOGRAM format, with a preamble, address, telephone
number, text and signature, ready for delivery.  After the message has
been saved to your printer or disk, the message should be erased from
the BBS.  You use the KT command, which means "Kill Traffic", followed
by the message number.  In this case you would enter KT 7839 to erase
the message you took from the BBS.  This prevents the message from
being delivered again by someone else.

DELIVERING OR RELAYING A MESSAGE: Once you have received the NTS
Radiogram, it should, of course, be handled expeditiously.  If it's
for your immediate area, you should deliver the message by telephone.
If you took the message for delivery to the local traffic net, you
should make an effort to see that it gets relayed as quickly as
possible.

SENDING MESSAGES: Any amateur can originate a message on behalf of
another individual, whether the person is a licensed amateur or not.
It is the responsibility of the originating amateur, however, to see
that the message is in proper form before it's transmitted.  A special
format is used for NTS traffic so that the messages are compatible
across the entire network. Each message should contain the following
components in the order given: number, precedence, handling
instructions (optional), the station of origin, check, place of
origin, time filed, date, address, telephone number, text and
signature.

When the message is ready to be entered into your local BBS, you must
use the ST command, which means "Send Traffic", followed by the zip
code of the destination city, then @ NTS followed by the two letter
state abbreviation. The form used is ST ZIPCODE @ NTSxx.  A message
being sent to Boston, MA 02109 would be entered as follows:  ST 02109
@ NTSMA and a message for Iowa City, IA 52245 would be entered as ST
52245 @ NTSIA.  The message SUBJECT or TITLE should contain "QTC 1"
followed by the destination city and state and the telephone area code
and exchange, if available.  See the examples in the listing above.
Only one NTS message should be included in each packet message.  The
actual radiogram should be included entirely within the TEXT of the
packet message, including all of the components listed above.  End the
message with the usual Control-Z.

IN TIME OF EMERGENCY: The National Traffic System functions on a daily
basis as a public service for both your fellow hams and the general
public. It serves another function as well.  The NTS provides a well
oiled and trained national system of experienced traffic handlers able
to handle large volumes of third party traffic accurately and
efficiently during disasters.  At least that is the goal.

REFERENCE MATERIAL:  The ARRL booklet "An Introduction to Operating an
Amateur Radio Station" offers detailed information on handling and
preparing NTS Radiograms.  The file "HOWTO.NTS" gives a complete
rundown on how to prepare and send an NTS message on packet.  Check
your local BBS files section for it.  You should also find several
other files such as "DELIVERY.NTS" and "WHATIS.NTS" that will provide
you with a wealth of information.  Check them out if you want to get
involved.  Your help will be welcome!

- - -


INTRODUCTION TO PACKET RADIO - Part 13 - by Larry Kenney, WB9LOZ

In this part of the series we'll take a look at many of the TNC
commands available to you that we haven't covered in previous
articles.  We will be discussing the commands used in the TAPR TNC2
and TNC2 clones.  You might find that some of the commands are not
available in your particular TNC or that they're used in a slightly
different manner than the one explained here.  Please refer to your
owner's operating manual for specific details on how to use these
commands in your TNC.

8BITCONV:  This command enables the transmission of 8-bit data in
converse mode.  Used with AWLEN - see below.  For normal packet
operation, such as keyboard to keyboard transmissions, use of bulletin
boards, and transmission of ASCII files, 8BITCONV should be OFF.  If
you need to transmit 8-bit data, set 8BITCONV ON and set AWLEN to 8.
Make sure that the TNC at the receiving end is also set up this way.
This procedure is normally used for transmission of executable files
or a special non-ASCII data set.

AWLEN:     This parameter defines the word length used by the serial
input/output port of your TNC.  For normal packet operation, as
described above, AWLEN should be set to 7.  Set to 8 only if you're
going to send 8-bit data.

AX25L2V2:  This command determines which level of AX.25 protocol
you're going to use.  If OFF, the TNC will use AX.25 Level 2, Version
1.0.  If ON, the TNC will use AX.25 Level 2, Version 2.0.  Note: Some
early TNCs will not digipeat Version 2.0 packets.  With AX25L2V2 OFF,
if your TNC sends a packet and the packet doesn't get acknowledged the
first time it was sent, it will send it again and again, until an
"ack" is received or the TNC retries out.  With AX25 ON, if your TNC
sends a packet and doesn't receive an "ack" the first time, it will
send a poll frame to see if the other TNC received the packet.  If
yes, then it would continue, if not then it would send the last packet
again.  The advantage here is that short poll frames are sent, rather
than long packets containing data.  This can greatly reduce channel
congestion.  For VHF/UHF operation, it is almost essential that every
TNC have AX25L2V2 ON.  Many operators have suggested that Version 2.0
NOT be used on the HF bands as it tends to clutter the frequency with
poll frames.  See the CHECK command below for related information.

BEACON:    Used with EVERY or AFTER to enable beacon transmissions.

   BEACON EVERY n  -  send a beacon at regular intervals specified by
                      n.

   BEACON AFTER n  -  send a beacon once after a time interval
                      specified by n having no packet activity.

                      n = 0 to 250  -  specifies beacon timing in ten
                      second intervals.

                      1 = 10 seconds, 2 = 20 seconds, 30 = 300 seconds
                      or 5 minutes, 180 = 1800 seconds or 30 minutes,
                      etc.

For example, if you set BEACON EVERY 180 (B E 180), the TNC will
transmit a beacon every 30 minutes.  If you set BEACON AFTER 180 (B A
180), the TNC will transmit a beacon after it hears no activity on the
frequency for 30 minutes.  B E 0 will turn the beacon off. The text of
the beacon is specified by BTEXT and can contain up to 120 characters.
The path used for the beacon transmission is specified by the UNPROTO
command.  YOU SHOULD USE BEACONS INTELLIGENTLY!  Beacons are often a
point of controversy in the packet community because they tend to
clutter the frequency if used too frequently.  You should keep your
beacons short and infrequent, and they should only be used for
meaningful data.  Bulletin boards use the beacon for advising the
community of who has mail waiting for them, clubs use beacons for
meeting announcements, beacons are used for weather warnings, etc.

CHECK n    Sets a timeout value for a packet connection.  Operation
depends on the setting of AX25L2V2.  The value of CHECK (n) determines
the timing.  Value may be 0 to 250.  Check set to 0 disables the
command. If a connection between your station and another exists and
the other station seems to "disappear" due to changing propagation or
loss of an intermediate digipeater, your TNC could remain in the
connected state indefinitely.  If the CHECK command is set to a value
other than 0, the TNC will attempt to recover.  The setting of
AX25L2V2 will determine what action is taken. If AX25L2V2 is ON, the
TNC will send a "check packet" to verify the presence of the other
station if no packets have been heard for n * 10 seconds. (n = 1 = 10
seconds, n = 5 = 50 seconds, n = 30 = 5 minutes, etc.)  If a response
is received, the connection will remain.  If no response is received,
the TNC will begin the disconnect sequence, just as if the DISCONNECT
command had been sent.  If AX25L2V2 is OFF, after no packets are heard
for n * 10 seconds, the TNC will not send a check packet, but will
begin the disconnect sequence.

CMSG       Enables the automatic sending of a connect message whenever
a station connects to your TNC.  If CMSG is ON, the TNC will send the
message contained in CTEXT as the first packet of the connection.
CTEXT can contain up to 120 characters.  This feature is often used
when the station is on but the operator is not present.  The connect
message is used to advise the other station of that fact, and often
says to leave a message in the TNC buffer.  If CMSG is off, the text
message is not transmitted.

KISS       KISS enables the TNC to act as a modem for a host computer,
allowing programs such as TCP/IP, the G8BPQ Packet Switch, various BBS
programs, and other programs using the Serial Link Interface Protocal
(SLIP) to be run.  Before turning KISS on, set the radio baud rate and
terminal baud rate to the desired values.  Set KISS to ON and then
issue a RESTART command.

                                        (continued in part 14)

- - - -


INTRODUCTION TO PACKET - Part 14 - by Larry Kenney, WB9LOZ

TNC COMMANDS - continued from Part 13

MAXFRAME   Sets the upper limit on the number of unacknowledged
packets the TNC can have outstanding at any time.  (The outstanding
packets are those that have been sent but have not been acknowledged.)
It also determines the maximum number of contiguous packets that can
be sent during one transmission.  Value can be set from 1 to 7.  The
best value of MAXFRAME depends on the frequency conditions.  The
better the conditions are, the higher the value you can use.  If
conditions are poor due to the amount of traffic on the frequency,
noise, or other variables, (shown by lots of retries) MAXFRAME should
be reduced to improve throughput.  The best value of MAXFRAME can be
determined through experimentation.  MAXFRAME of 1 should be used for
best results on HF packet.

MFILTER     This command allows you to enter up to four ASCII
character codes, 0 - $7F, for the control characters that you want
eliminated from your monitored packets.  Codes may be entered in
either Hex or Decimal. Here are the ASCII codes for some of the more
troublesome control characters found in monitored packets:

   HEX   DEC   FUNCTION   POSSIBLE RESULT
   $07    07   Control G  Rings your bell or "beeps" your speaker
   $0C    12   Control L  Form feed - could clear your screen
   $13    19   Control S  Can cause your screen to stop scrolling
   $1A    26   Control Z  Can clear your screen
   $1B    27   Escape     Can cause your cursor to move to a random
                          point on your screen and can raise havoc
                          with printer control.

AEA has added a new code, $80, that will not allow ANY control
characters to be displayed on the user's screen from monitored
packets.

MHEARD     An immediate command that causes the TNC to display a list
of stations that have been heard since the command MHCLEAR was given
or the TNC was powered on. This command is useful for determining what
stations can be worked from your QTH.  Stations that are heard through
digipeaters are marked with an * on most TNCs.  On the AEA PK-232, the
stations heard direct are marked with the *.  (Check your TNC manual.)
The maximum number of stations in the list is 18.  If more stations
are heard, earlier entries are discarded.  Logging of stations heard
is disabled when the PASSALL command is ON.  If the DAYTIME command
has been used to set the date and time, entries in the MHEARD list
will show the date and time the stations were heard.

PASSALL    Causes the TNC to display packets that have invalid
checksums. The error-checking is disabled.  If PASSALL is ON, packets
are accepted for display, despite checksum errors, if they consist of
an even multiple of eight bits and are up to 330 bytes.  The TNC
attempts to decode the address field and display the callsigns in
standard format, followed by the text of the packet.  PASSALL can be
useful for testing marginal paths or for operation under unusual
conditions.  PASSALL is normally turned OFF.

SCREENLN n This parameter determines the length of a line of text on
the terminal screen or platen.  Value may be 0 to 255.  A (CR-LF)
carriage return and line feed are sent to the terminal in Command and
Converse modes when n characters have been printed.  A value of zero
inhibits this action. If your computer automatically formats output
lines, this feature should be disabled.

TXDELAY n  This parameter tells the TNC how long to wait before
sending data after it has keyed the transmitter. All transmitters need
some start up time to put a signal on the air.  Some need more, some
need less. Synthesized radios and radios with mechanical relays need
more time, while crystal controlled radios and radios with diode
switching require less time.  External amplifiers usually require
additional delay.  Experiment to determine the best value for your
particular radio.  TXDELAY can also be useful to compensate for slow
AGC recovery or squelch release times at the distant station.

There are many additional commands available to you.  I've only
covered the ones that I thought would be the most useful to you.
Spend some time reading the owner's operating manual that came with
your TNC to discover some of the surprises the other commands offer.
New versions of the TNC software have added several commands that you
might find useful in your packet operating.

- - - -


INTRODUCTION TO PACKET RADIO - Part 15 - by Larry Kenney, WB9LOZ

Here are some tips to help make your packet operating more enjoyable.
Whether it's while making local QSOs, checking into a BBS or mailbox,
or working DX, there are a few things you should take into
consideration that will help eliminate problems and waiting time and
will increase your throughput.  ("Throughput" is a word that has come
into use by packet operators that means the amount of usable packet
information received by the distant station.)

When connecting to another station, don't use a digipeater or node
unless you have to.  Each digipeater you add to the path increases the
time required to get your signal to its destination and to get an
acknowl- edgement returned.  It also increases the chance for
interference and for collisions with other packets.  You'll be amazed
at the difference in throughput when comparing a direct connect to one
with just one digipeater in the path.

The packet node network, as discussed in previous articles in this
series, does a great deal to help you get your packets through, but
you must remember that throughput there, too, is affected by the
number of nodes and the conditions between you and the destination
station.  The big advantage of the nodes is that the acknowledgements
do not have to return all the way from the destination station.
Packets are acknowledged from node to node, so that eliminates a large
part of the problems encountered.  Getting the original packet
through, however, remains to be as much of a problem for the nodes as
it is for you when using digipeaters.  It can take several minutes to
get a packet through when you're working a station some distance away.

Dr. Tom Clark, W3IWI, has determined that for EACH HOP in a packet
path the loss of packets can vary anywhere from 5% to 50% depending on
the amount of traffic.  Remember, each digipeater and node adds a hop,
so multiply those percentages by the number of hops, then multiply by
2 to account for the acknowledgement, and you can see how quickly the
path deteriorates as traffic increases and digipeaters and nodes are
added to it.

If you have a choice, use a frequency that doesn't have a lot of other
traffic on it.  It makes sense that the more stations there are on
frequency, the more chances there are for collisions and retries.  A
path that will work perfectly without a lot of traffic, can become
totally useless under heavy traffic conditions.  Just one additional
station on the frequency can decrease throughput by about half in many
cases.

Another consideration, especially if working over a long distance, is
atmospheric conditions.  You might not have experienced this before on
VHF, but with packet's high sensitivity to noise, a slight change in
signal strength can mean the difference between getting your packets
through or not getting them through.  An example of one path that is
very vunerable to conditions due to its distance is from W6AK-1 on Mt.
Vaca to WB6AIE-1 on Bald Mountain in Yosemite National Park on 145.05
MHz.  Most of the time, packets go between these two nodes without any
problem, but there are times, especially when it's a hot summer day in
the Sacramento Valley, when it's impossible to get a packet from one
to the other.  In the Bay Area, the fog has a drastic affect on VHF
signals.  When a fog bank is moving in off the Pacific, it can act as
an excellent reflector.  Signals that are not normally heard can reach
signal strengths of 40 over S9.

Multipath is another problem that can greatly affect your packet
signal. Multipath is the term used to describe the receipt of multiple
signals from one source due to reflections off of buildings, hills or
mountains.  The "ghost" in a television picture is a form of mutipath.
A station with a very strong signal into a digipeater or node often
cannot use that path if multipath causes the signal to be distorted.
Each packet is checked for 100% accuracy and is not acknowledged
unless it is.  Multipath reflection can cause occasional bits to be
lost so you end up with multiple retries and a poor path even with
strong signals.

To sum up, for best results on VHF use the least number of digipeaters
and nodes as possible, use a frequency with low activity, and be aware
of atmospheric conditions and multipath problems.

If you use packet on HF, remember to change your transmit baud rate to
300 and to use a short PACLEN (a value of 40 seems to work quite well)
and a MAXFRAME of 1.  The chances of getting a short packet through
the noise and QRM are much better than for a long one.

_ _ _



INTRODUCTION TO PACKET RADIO - PART 16 - by Larry Kenney, WB9LOZ

In this article, let's do some reviewing.  I'm going to present a
short quiz on packet, covering the basics that I've presented in the
past 15 parts.  Let's see how well you can answer the following
questions without looking back at the past articles.  In Part 17 I'll
discuss each question and give you the correct answers.

1. What are the three TNC modes of communication?
    a. Connect, Converse, Terminal
    b. Command, Converse, Terminal
    c. Command, Converse, Transparent
    d. Command, Connect, Transparent

2. What TNC command is used to set the transmit path for beacons and
   CQs?

3. What is the TNC command CHECK used for?

4. While you're connected to another station, what command is used to
   monitor other traffic on the frequency?

5. If you saw one of the following lines on your screen when in
monitor mode, what would the asterisk indicate?

      W6ABC-3>N6XYZ,W6PW-1*: Hi Bob
      W6ABC-3>W6PW-1*>N6XYZ: Hi Bob

   (Displays vary with various TNCs, so both common types are shown.)

6. Why does the packet node network improve communications?

7. If you're connected to a station in New Mexico using the node
   network, how do you disconnect?

8. If N6ZYX-2 connected to you via a node, what would the SSID of the
   station become at your end of the connection?

9. When you're connected to another station, what are the two most
   probable causes for packets not to be received by the other
   station?

10. There are several basic commands used on a packet bulletin board
    system.  Indicate what you would enter to perform the following:

      a. Receive a list of messages.
      b. Download a file in the General (ID G) directory called
         FCCEXAMS.89.
      c. Enter a private message to Jim, WA6DDM, who uses the W6PW BBS
         in San Francisco, California.
      d. Read message 7134 with complete forwarding headers.
      e. Find out what stations have been heard by the BBS on port B.

11. To send an NTS message via packet addressed to Tom Smith, 123 Main
    Street, Keene, NH 03431, telephone [phone], what would you
    enter at the BBS prompt?

12. If a message has a STATUS of BF, what does that indicate?

13. If you received a message from a friend in Chicago that had been
    forwarded to your home BBS through four other BBSs and the message
    had a Date/Time of 0316/2245 when you listed it, which of the
    following is a TRUE statement?

      a. The message was written at 2:45 pm on March 16.
      b. The message was entered into the BBS by your friend at 2245
         on March 16.
      c. The message was forwarded by your friend's BBS in Chicago at
         2245 on March 16.

      d. The message was received at your home BBS at 2245 on March
         16.

14. If you wanted to send a message to your friend John, W4IP, but you
    didn't know what the call of his home BBS was, what could you do
    to try and find out what the call is?

15. What is the maximum value for MAXFRAME?  If you're working a
    station on 30 meters and are sending a lot of retries, should you
    increase or decrease MAXFRAME?

Well, how did you think you did?  We'll take a look at the answers to
these questions and more in part 17.

- - - -


INTRODUCTION TO PACKET RADIO - PART 17 - by Larry Kenney, WB9LOZ

How did you do on the review quiz in the previous part of this series?
If you haven't taken it, you might want to read part 16 and take the
quiz now before reading any further.

Here are the correct answers and the series part numbers where you can
read more about the subject:

1 - Answer C is correct.  The three TNC modes of communication are
Command, Converse and Transparent.  Command mode is for communicating
with the TNC. The Converse mode is for normal QSOs, connects to a BBS
or mailbox, etc. and Transparent mode is used for binary file
transfer.  (Part 2)

2 - The UNPROTO command is used for setting the transmit path for both
beacons and CQs. (Parts 3 and 13)

3 - The CHECK command is used for setting a timeout value in your TNC.
If set to a value other than zero, the TNC will attempt to recover a
connection after a certain specified time if nothing is received from
the other station.  This command is used in combination with the
AX25L2V2 command.  (Part 13)

4 - The MCON command (Monitor while CONnected) is used to monitor
other traffic on the frequency while you're connected to another
station. (Part 3)

5 - When monitoring, the asterick indicates the station that you
actually hear the packet from.  The MRPT command must be ON for the
monitor display to show digipeaters.  (Part 2 and 3)

6 - The packet node network improves communications because packets
are acknowledged from your station to the first node, and then node to
node to the destination.  A packet doesn't have to reach the
destination before an ack is returned.  (Parts 4, 10 and 11)

7 - When using the node network (no matter who you're connected to)
you disconnect by going to command mode on your TNC and entering a D,
just like at other times.  The fact that you're using several nodes or
are connected to a distant station makes no difference.  The network
will take care of disconnecting all stations and links.  (Parts 4, 10
and 11)

8 - N6ZYX-2 would appear as N6ZYX-13 if he connects to you using a
node. The nodes change the SSID using the formula 15-N.  (Part 10)

9 - The two most probable causes for a packet not to get through are
collisions with other packets on the frequency and noise due to weak
signals.  (Part 15)

10 - BBS commands:
  a. To receive a list of messages: enter L
  b. To download a file in the General (G) directory called
     FCCEXAMS.89, you'd enter DG FCCEXAMS.89
  c. To enter a private message to Jim, WA6DDM: SP WA6DDM @ W6PW.CA
     (The "@ W6PW" is not needed if you're using the W6PW BBS.)
  d. To read message 7134 with headers: RH 7134
  e. To find out what stations were heard on port B of the BBS, you'd
     enter JB
 (Parts 5, 6, 7 and 8)

11 - If you wanted to send an NTS message to Tom Smith, 123 Main
Street, in Keene, NH  03431, you would enter the following at the BBS
prompt > ST 03431 @ NTSNH               (Parts 6 and 12)

12 - A message with a STATUS of BF means that the message is a
bulletin and that it has been forwarded to all stations that are
supposed to receive it from the BBS you're using.   (Part 8)

13 - Answer D is correct.  The date/time shown on a message when it's
listed is the time the message was received at the BBS you're using.
Please note that the date/time of a message indicates whatever time
the BBS your using is set to, and that could be local time or zulu
time, UTC, GMT, or whatever.  Most BBSs are now set to zulu time (UTC,
GMT), but a few still use local time.  When you read a message, you
should be able to read the date and time the message was written from
the message header. (Part 8)

14 - To find the call of the HOME BBS of your friends, use the White
Pages Directory.  If the BBS you're using has the WP feature enabled,
you will find the I command to be useful, otherwise send an inquiry to
WP.  (Part 9)

15 - The maximum value for MAXFRAME is 7.  MAXFRAME is the number of
packets transmitted by your TNC contiguously, and the number of
unacknowledged packets the TNC can have outstanding.  You decrease
MAXFRAME when the conditions are poor.  Your TNC will send fewer
packets at one time, so there will be less information to collide with
other packets on the frequency and less chance of information being
wiped out by noise. (Part 14)

There is no passing grade on the quiz.  It was designed for you to
check your general packet knowledge, and you'll have to be your own
judge of that. I hope you did well on it!

- - - -


INTRODUCTION TO PACKET RADIO - PART 18 - by Larry Kenney, WB9LOZ

In the previous 17 parts of this series, I have attempted to cover all
of the basics of packet radio - from setting up your TNC and making
your first QSO, to using digipeaters, the packet node network,
bulletin board systems and mailboxes.  Many of the TNC commands have
been explained, including the best settings for normal packet use, and
I've offered suggestions that should make it easier and more enjoyable
for you to use packet radio.

Changes in packet are made quite frequently as new versions of the
software for the TNC, node network and bulletin boards are released.
Try to be aware of these changes so that you can take advantage of the
latest information.

Now you might want to investigate some of the newer developments in
packet radio.  There are several programs available for making special
use of packet, such as the Packet Cluster software used by the DX
Spotting Networks, TCP-IP, Tex-Net, Conference Bridging, etc. PAC-SAT,
the packet satellite program, is growing in popularity as more
satellites carrying packet radio equipment are released.  High speed
modems running at speeds of up to 56 kilobaud are just around the
corner for general use.  You'll find a wide variety of special
interests available to you.

I'd like to thank the following for help in preparing this series: Don
Simon, NI6A; Bill Choisser, K9AT; Don Fay, K4CEF; Scott Cronk, N7FSP;
and Hank Oredson, W0RLI.

If you have any comments on this "Introduction to Packet", or if you
have any questions on the topics discussed, want to suggest new topics
for inclusion in future articles, or want to correct or update any of
the information contained in the series, please send a packet message
to me. Your comments will be appreciated.  I hope that you've found
the series to be informative and helpful in making packet more
enjoyable for you.

73, Larry Kenney, WB9LOZ @ W6PW.#NOCAL.CA.USA.NA

                       THE  END   of  18 PARTS