Gold Medal Software 3/Gold Medal Software - Volume 3 (Gold Medal) (1994).iso/misc/hod003.arj/FILE6.003

Text File | 1994-03-20 | 29KB | 516 lines

INTRODUCTION TO PACKET RADIO - PART 6 - By Larry Kenney, WB9LOZ

In this part of the series we're going to take a look at how to use
NET/ROM and THENET for making contacts.  It's a way of making your
operating time on packet more enjoyable due to the increased relia-
bility of the network and the greatly expanded area that you can
reach.

When a digipeater adds NET/ROM or THENET it becomes a digipeater/node.
This means that you can still use it as a regular digipeater, but you
can also use it to access a far reaching network of nodes.  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, your packets no longer have
to reach their destination before acknowledgements are returned to your
TNC.  Now, each node acknowledges your packet as its sent along the way
toward its destination.

Here's how you use the nodes network:  No matter what station you want
to work, you connect to the closest node.  When you connect, your TNC
automatically switches to converse mode, so 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 node.

Once you're connected to the node, enter "NODES" <return> and you'll
receive a list of the other nodes available to you.  It's sometimes
difficult to determine the location of the nodes from this list, since
the IDs and callsigns you receive aren't always very descriptive.  You
might find the node maps and listings that are available on most packet
bulletin boards to be useful tools.  With these maps and listings, you
can easily determine where the nodes are located.  Make sure you have a
recent copy, as new nodes are being added quite frequently.

Let's say you want to have a QSO with N6XYZ.  You first must determine
what node is closest to that station.  Let's say it's W6AMT-3.  Once you
know the call of that node, you connect to it WHILE STILL CONNECTED TO
YOUR LOCAL NODE.  You use standard protocol, C W6AMT-3.  Your TNC will
send this as a packet to your local node, and your local node will ack
it.  Your TNC is happy because the cycle is completed as far as it's
concerned.  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'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.

Now that you're connected to W6AMT-3, enter "C N6XYZ".  Again, your TNC
will send this as a packet to your local node and the 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 diff-
erence -- your TNC is receiving acknowledgements from your local node,
and N6XYZ is receiving acknowledgements from W6AMT-3.  That long path is
eliminated for both TNCs, retries are greatly reduced, and your packets
get through much faster.  When you're finished with the QSO, you discon-
nect in the normal manner -- go to Command Mode using Control C and enter
"D" <CR>.  The entire path will then disconnect automatically for you.

If you've been monitoring lately, you might have seen the nodes in action
and wondered why they were sending all of those weird symbols like @fx/<~|.
What you're seeing is the nodes communicating with each other, updating
their node lists.  You also might have noted callsigns with high numbered
SSIDs, such as WB9LOZ-15, WA6DDM-14, 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 at 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.

In part 7 of this series, I'll discuss some of the other commands avail-
able to you on the nodes, including how to call CQ.

INTRODUCTION TO PACKET RADIO - Part 7 - by Larry Kenney, WB9LOZ

The network of NET/ROM, THENET 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 new stations and the interconnecting
links, you can now connect to stations in many far distant places using
your 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 possi-
bility of working a station just about anywhere.

A complete listing of NET/ROM NODES is available on most BBSs, as well
as maps showing how everything is tied together.  The lists are updated
frequently by Scott, N7FSP, in San Jose.

NET/ROM is very simple to use, and I understand that THENET and KAM
nodes are very similar.  As explained in part 6 of this series, to use
NET/ROM, you first connect to a local node.  You then have several
options -- connect to another station within range of the node, connect
to another node, obtain a list of the nodes that are available, check
user status, or answer or call CQ.

There are only FOUR commands to remember to use the system: CONNECT,
NODES, USERS and CQ.  The CONNECT command (which can be abbreviated as C)
works just like the CONNECT command in normal usage, except that you can
connect from one node to another.  For example, you can CONNECT to W6AMT,
and then do another CONNECT to WA6RDH-1, another node.  Let's go through a
simple connection via NET/ROM.  Say I want to connect to a friend in Reno,
within reach of WA7DIA-1, a node in the Sierras.  I would first connect
to my local node, say W6AMT, then connect to WA7DIA-1, then connect to my
friend.  Here's what it would look like:
C W6AMT
Connected to W6AMT
C WA7DIA-1
SFO:W6AMT} Connected to RNO:WA7DIA-1
C K7ZYX
RNO:WA7DIA-1} Connected to K7ZYX
You then conduct your QSO, and disconnect in the normal manner.  (Go to
command mode on your TNC and enter a D.)  One disconnect command will
disconnect you from the entire network.

You'll note that many of the nodes have aliases, such as SFO for W6AMT,
VACA for WA6RDH-1, SSF1 for KA6EYH-1, etc.  With NET/ROM, you can connect
to the alias identifier, so "C SFO" would work as well as "C W6AMT".

Once connected to a node, the other commands come into play.  The NODES
command (which can be abbreviated as N) will give you a listing of other
nodes available from the node you're connected to.  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.  The CQ command (which
cannot be abbreviated) is, of course, used for calling CQ, but also can
be used for replying to the CQ of another station.  The CQ command is
available only in NET/ROM version 1.3.

There are two other commands, but they're used for status information
only.  IDENT will simply give you the identification of the node you're
on, and PARMS (Parameters) is for the owner's use in determining how his
station is working.

Using the NET/ROM 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:
  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:
  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
  Hi!  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--give other stations a
chance to reply to your first one!

NOTE: As mentioned above, the CQ command was introduced in NET/ROM version
1.3.  On a node using an earlier version, you will get the message "Invalid
command".  The USERS command can be used to determine which version a node
is using as shown in the example above.  If you cannot initially connect
to a node using version 1.3, that doesn't stop you from using the CQ command.
Once you're connected to a node you can reach, simply connect to one that
has version 1.3.

Give the new CQ feature a try.  You might work someone locally, in Phoenix,
Seattle, or on the East Coast.  You never know where you'll get connected
to next!  Enjoy!

(Material distributed by Scott, N7FSP, was used in the preparation of this
part of the series.)

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

In this part of the series I'll explain, in detail, the various parts
of the packet message.  The following is an example of what you see
when listing or reading messages on a BBS.  On some systems, the infor-
mation is displayed in a different order.

MSG# STAT SIZE TO     FROM   @ BBS  DATE/TIME SUBJECT
4723 P    1084 WD5TLQ WA6XYZ N5SLE  0604/1240 Software working great!

The message number is assigned by the BBS program when the message
is entered and cannot be changed.  The numbers are assigned sequen-
tially.

Next you find the STATUS of the message which includes several different
bits of information about the message.

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 not listed for anyone except the sender and the addressee,
and only they can read them.  (Of course, anyone in monitor mode can
see a message of this type as it's being sent, because nothing on packet
is absolutely private.)  Traffic messages, type T, are messages used for
handling traffic on the National Traffic System.  (Refer to part 8 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 for-
warded, 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 punctu-
ation in the message.

TO, normally, is the callsign of the addressee, but it is also used to
categorize messages on particular topics.  You might find a message
addressed TO AMSAT, TO PACKET or TO ARRL, when it is actually a message
about AMSAT, about PACKET or having to do with the ARRL.

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 to a specific designator.  In the example, the message
would be automatically forwarded to WD5TLQ at the N5SLE BBS.  You can
enter special designators, such as ALLCAN, in the "@ BBS" column for
multiple forwarding to specific areas.  (See Part 5 of this series for
details on using forwarding designators.)

Next is the DATE and TIME when the message was received at the BBS.
Keep in mind that the date and time are shown in the time used by the
BBS, and can be either local time or Zulu.

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 remaining parts
are in the body of the message, and are seen only when the message is read.

If a message has been forwarded from another BBS, you'll see forwarding
headers at the top of the actual message.  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 code, 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 to determine how
long it took a message to be forwarded from the source to destination,
and they can be used to determine the path the message took to reach you.

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.  Do not 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 complete the text with either a Control-Z or these three characters:
the "slash" (/) plus the letters "EX".  On some BBSs this must be on a
line by itself.  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.

- - -

(In the next part of this series, we'll be discussing tips on how to make
your packet operating time more enjoyable.)

INTRODUCTION TO PACKET RADIO - Part 10 - by Larry Kenney, WB9LOZ

Here are some tips to help make your packet operating a little 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 waiting time and
increase your throughput.

When connecting to another station, don't use a digipeater unless you
have to.  Each digipeater you add to the chain 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.

Also, 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.

Dr. Tom Clark, W3IWI, has determined that for EACH HOP, 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.

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 vulnerable 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
digipeaters without any problem, but there are times, especially
when it's a hot summer day in the Sacramento Valley, when it's impos-
sible 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.

NET/ROM, TheNet, and KA-Nodes, as discussed in previous articles in
this series, do a great deal to help you get your packets through,
but you must remember that they, too, are affected by the number of
hops, the traffic load and the atmospheric conditions between you and
the destination station.  The big advantage to NET/ROM is that the
acknowledgements do not have to return all the way from the desti-
nation 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.
_ _ _

In the next part of this series we take a look at some of the more
obscure TNC commands and how you use them.

73, Larry, WB9LOZ
INTRODUCTION TO PACKET RADIO - Part 11 - 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 trans-
missions, 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.
Some early TNCs will not digipeat Version 2.0 packets.
Version 2.0 has added features.  See the CHECK command below.  Many
operators have suggested that Version 2.0 NOT be used on the HF bands
as it tends to clutter the frequency.

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 dis-
connect 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 when-
           ever 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.

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.

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.