World of Ham Radio 1994 January/AMSOFT_1994.iso/packet/docs/packet02.doc

Text File | 1993-12-31 | 8.2 KB | 137 lines

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.

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