QRZ! Ham Radio 5/QRZ Ham Radio Callsign Database - Volume 5.iso/files/arrl/hiram/packet.new

Text File | 1994-11-20 | 14.6 KB | 305 lines

An Amateur Packet Radio Overview

by Rich Bono (NM1D)

October, 1990 (revision 1.2)

The following is the result of a non-amateur asking some basic questions
about amateur packet radio.  Several of us thought that this information
would be useful to others who are interested in amateur packet
operations. Thanks to Tim Dayger for asking the right questions, and to
Patty Winter (N6BIS) for her editing skills.  I hope that this will be
of help to many others.  You may reproduce and distribute this as long
as my credits remain. -- Rich Bono (NM1D)

Our potential amateur packet radio operator asks:

I've used networks, on-line services, and bulletin board systems (BBS)
for years, but I've never really paid much attention to amateur packet
radio. I'm starting from scratch, and need to have some idea of where to
begin.

Just what IS amateur packet radio?

Amateur packet radio is (yet another) digital transmission method
available for use via amateur radio.  It provides 'error free'
transmission and reception of messages (information/data/etc.) between
two stations.  This error-free capability is a prime consideration.
Error free in this context does not mean that your typing or spelling
mistakes will be fixed, but that all transmitted 'data' will be received
100% intact, as sent.  In fact, if the data cannot be delivered 100%
intact, the transmission is eventually aborted and the user is informed
that there is no longer a connection between the two stations.

The 'packet' in 'packet radio' comes from the method of transmitting
your information over the air.  Your data is broken up into packets (or
blocks) that are transmitted.  Each packet contains the sending and the
receiving station call-signs and some optional routing information.  A
packet can contain from 0 to 256 data (or information) bytes.  The users
normally do not need to be concerned with this 'packetizing' of their
messages.  Each packet is sent and then acknowledged by the receiver
when received.  If a packet is not received correctly, then it is
automatically re-transmitted (up to a maximum number of times).  You
normally don't have to know about all this to use packet radio.  The
'packetizing' happens automatically, without any thought or actions
required by you.

One of the more popular protocols used for amateur packet radio is known
as AX.25.  This is somewhat similar to the commercial X.25 standard.
There is also a growing TCP/IP user base.  If you are not network
oriented, then the details of these protocols are not important to you
as an operator of a packet radio station. Be aware that most packet
radio operation at this time is at 1200 baud. This will seem slow when
compared to what it happening on networks, and on telephone BBSs....
but what is gained is world-wide access, for NO COST. Once you have your
equipment, and your license, there are no fees (except for the
electricity that your computer and other equipment use).  There are a
growing number of amateurs who are experimenting with 2400 and even 9600
(or higher) baud operation, so it shouldn't be too long before these
faster rates become very popular!

What kind of equipment do I need, and how do I use it with my PC?
 Since you own a PC, you already own the most expensive part of an
amateur packet radio station.  The other piece of equipment that you
need is the TNC (terminal node controller).  The TNC contains all the
software and special hardware that you need.  It actually contains the
modem (to interface with your radio) and (usually) a microprocessor with
the packet software contained in EPROM.  You interface your PC (or even
a simple dumb ASCII terminal) with the TNC via serial RS-232.  Use your
favorite terminal emulation software on your PC (the same software that
you use with your telephone modem will probably work fine).  This is
just as easy as connecting your computer to a modem.  If you don't want
to use the serial port of your computer, there are TNCs available that
will plug directly into the bus.

If you don't have a PC (personal computer), then almost any RS-232 ASCII
terminal will work with most of todays TNCs.

The most popular packet frequencies in the USA are in the two-meter band
(144-148 MHz).  Check out the following frequencies (they may be
different in your area; ask a local amateur if you don't hear anything).
Even the typical 'police scanner' can be used to listen to these
frequencies:

         145.01, 145.03, 145.05, 145.07, 145.09 MHz

If the above are busy, many areas also use:

         144.91, 144.93, 144.95, 144.97, 144.99 MHz

Yes, this is with an average FM transceiver set for SIMPLEX operation
(transmitting and receiving on the same frequency).

If there are packet radio transmissions you should hear a sound like:

                BBBBbbbbbrrrrraaaaaaappppppp

How much technical or hardware proficiency is required to use a packet
radio system?

If you can plug an RS-232 cable into a modem, and wire the TNC to your
radio, then you have all the ability that you need.  I am sure that
there are hams in your area who would be glad to help you if you are not
comfortable with wiring a microphone connector.  Most TNCs connect to
the microphone plug of an FM transceiver, normally only needing push-to-
talk and transmit audio connections, and a connection to the speaker
audio output from the FM receiver.  This consists of about five wires,
and can usually be done without removing the covers of the radio (these
are normally external connections).

Installation really is very simple, and once it is done, there is
virtually no maintenance.  Just plug in your TNC in place of your
microphone and external speaker, and you're on the air...  to return to
voice operation, plug in your microphone.  If you like, build a simple
switch box to allow easy changing between your TNC and voice operation.
I don't recommend it, but some people wire the TNC and microphone in
parallel, so that they don't need to change the plugs, or switch
anything at all.

What's out there for me to access via packet radio and what potential is
there for growth?

This is the interesting part!  I believe that packet radio is still in
its infancy.  It seems like every day a new application for packet radio
is announced...  some are good ideas...  others not.  By the time you
read this, a lot of the information presented here will probably be out
of date; yes this technology is progressing!!!

Here is a *simple* list that barely highlights some of the available
uses of amateur packet radio..  I am SURE that I have forgotten
something and left it off the list:

EMAIL:

At this time we have world-wide email (electronic mail) distribution. I
personally have received email from a few continents, and from all over
the USA. Of course, this is limited by the amateur radio rules and
regulations, so there cannot be any commercial messages.

Local networks:

Here in New England we have connectivity over most of the region.  I can
connect to other stations from the following areas consistently: Canada
(Montreal), Vermont, New Hampshire, Maine, Connecticut, Massachusetts,
Rhode Island and New York.  I should note that I am located about 10
miles north of the MA/NH border (in Derry, NH).

Of course, on the HF (high frequency) bands there can be world-wide
connectivity, depending on many factors.

PacketCluster-DX spotting:

This is a specialized system that allows a couple of hundred users to be
connected to the same system at one time.  It is used by those amateur
operators who seek contacts with rare stations throughout the world.
When any one user 'finds' a rare station on the air, he simply types the
information (call-sign, frequency and mode) into his terminal, and
within a minute or so, all of the other users are informed of the rare
station!!! So-called "DXers" (people who like to hunt these rare
stations) LOVE this system.  These users can be spread over a wide area.
Our local packet cluster system has connectees from Maine to New York.

DOSGATE:

A system that allows you to execute programs remotely.  A DOSGATE system
may have many programs for you to use over the air.  You don't need to
download the programs to use them; you are actually running programs
remotely.  DOSGATE allows those who don't have a computer to run
programs via packet radio.

For example, my DOSGATE system has the following programs available for
use by remote packet users:

AUTOEXAM: Take sample amateur exams from Novice to Extra. You can use
AUTOEXAM as a study guide, or to see if you are ready for a certain
license exam.

SeeSats: Real time satellite tracking. Informs you of where the current
OSCAR (and other) satellites are located.

AUTOCALL:  On-line amateur radio USA call-sign lookup database. Simply
enter the call-sign of any amateur radio operator in the USA and it will
print out the name, address, license class
and previous call-sign (if any).

GAMES:  Several adventure-style games that can be played on-line.

Repeater database:  A database of many of the repeaters in the area.

Gateways:

Even though you may not own any HF or UHF equipment (many packet radio
operators only use a simple hand-held VHF transceiver), you can gain
access to other bands and operating modes by using a gateway.  A gateway
allows connectivity between two normally non-connectable communication
technologies.

In many areas not only are there major BBSs on the standard two-meter
Technician class frequencies and the 222 MHz Novice class sub-band, but
there are cross-band gateways available as well.  A Novice on the 222
MHz band can connect to a station on the 145 MHz band by going through a
gateway and be able to communicate with many other amateurs.

Public Service:

Many packet stations are used to help out with sending messages during
disasters.  Amateur radio operators help out whenever they can, and many
hams have their packet stations ready for portable operation to help
when needed.  There are many training exercises during each year to help
practice and test the readiness of the emergency stations.

OSCAR Satellites:

OSCAR stands for Orbital Satellites Carrying Amateur Radio.  We have our
OWN satellites in orbit that are dedicated for amateur radio use. There
are some satellites that are dedicated to packet radio (sometimes called
"PACSATS").  These are for 'store-and-forward' operations to help
distribute packet traffic around the world.

Bulletin boards:

These carry postings similar to the stuff on Usenet (or telephone BBSs)
and often have archives of useful files (such as local ham license
testing sites).  These are usually the same packet nodes that transport
email.

File transfers:

Better at 56 Kbaud (as some hams are doing), but feasible at 1200 baud.
On TCP/IP, you just start it and forget it, so you can do it overnight
or at some other time when you don't care whether it takes a while.

Databases:

In some areas there are HAZMAT (hazardous materials), call-sign, and
repeater databases accessible via the network.

Station-Station:

I almost forgot..  many people simply enjoy chatting with their
neighbors....  This could be with people across the street...  or in the
next state...  or half-way around the world!

I am sure that I have missed something.  You asked about potential...
as I mentioned at the beginning, we are just getting started!!!  Many
people are just finding out about packet radio.  I believe that the only
limitation is our imagination!! We could have a world-wide network (we
do currently have a 'slow-speed' world-wide network) in the near
future...  It just takes a little imagination...

How much will a packet radio set-up cost me? How COST EFFECTIVE is
packet radio?

Well, if you own the PC already...  TNCs can be purchased from about
$120.00 on up.  There are a few for less money, and several that provide
for operating on many digital modes in addition to packet radio (i.e.,
the Kantronix KAM will provide for packet (HF:300 baud/VHF:1200 baud),
AMTOR, RTTY, ASCII, NAVTEX, WEFAX, CW (Morse code),...).

If you already own an amateur FM transceiver (or an HF SSB transceiver)
then you have all the equipment needed.  If not, a two-meter FM
transceiver can be purchased for used from $100-250.00, new from $300.00
on up.

Cost effective....  Hmmm, well first be aware that amateur radio cannot
be used for any commercial or business purposes...  But where else can
one get hours (years) of enjoyment and service out of $470.00 ($350 for
a radio and $120 for a TNC, assuming you already have the computer or
terminal).  Note: This stuff can be contagious....  be forewarned!!

What legal issues do I need to consider regarding packet radio? Do I
need a license?

Yes, you need a valid amateur radio license.  There is (in the southern
New Hampshire area) packet radio activity on the Novice bands.  But if
you want access to the mainstream of packet radio, you will want at
least a Technician amateur radio license. (Although, as mentioned
earlier, some areas have an active packet radio network that is
accessible with the Novice amateur radio license.)

I've tried reading about amateur packet radio, but a lot of it is Greek
to me. Please suggest some reading materials such as books and magazines
that my campus or local libraries might carry.

There are a few books, etc...  but I have found that most assume that
you already know about amateur radio.  You need to find what we call
(ready for another term?) an "Elmer".  An "Elmer" is a friendly, helping
amateur radio operator who will take you under his/her wing to help and
guide you as much as you need.  I hope that you can find someone to help
you...  it takes a special kind of person to be an 'Elmer' (gosh I hate
that term).

Note: You can obtain help finding an Elmer from the American Radio Relay
League, 225 Main St., Newington, CT 06111, 203-666-1541, MCI: 212-5052.
Internet: [e-mail]. -- KA1CV

Good luck with your packet radio activities.  If you find this
information helpful, I would be glad to hear from you....  How?  Simply
send me a message via the amateur packet network, [e-mail]
from anywhere in the world!

/***********************t***************************************************\
* Rich Bono (NM1D)    If I could only 'C' forever!!    [e-mail] *
* [phone]          NEC Technologies Inc.                NM1D@WB1DSW *
\**************************************************************************yo