Packet Radio On The CBRS
Yes Or No?
Article
written and gratefully
re-produced courtesy of
Jack, ACBRO 469
Discussions on internet newsgroups have raised
the issue of a possible introduction of Packet Radio to the Citizens Band Radio
Service. Although the Australian Communications Authority have no proposal to
introduce such a system, it deserves worthy of consideration and debate as to
whether or not the CB fraternity would hold interest in having Packet Radio
implemented in the future.
We are all aware that channels 22 and 23 on the UHF CB
Radio service have been lost for voice communications in favour of
telemetry and telecommand systems. Packet Radio involves another kind of data
transmissions.
Quite often many object to a particular mode of communications simply because of
a lack of understanding as to how that mode operates and what the benefits are.
To this end ACBRO ask that you carefully study the article below and judge the
matter after you are certain you have a clear understanding of how Packet Radio
operates.
ACBRO thank one of its members, Jack, ACBRO 469, for his cooperation in
addressing this issue and describing what Packet Radio is in clear and precise
way. It is a basic summary of not only how Packet Radio works but also the
issues involved in an introduction of Packet Radio to the CBRS.
After reading the article ACBRO invite you to submit your thoughts and opinions
regarding an introduction of Packet Radio operation on channels
22 and 23 on the UHF CB Radio Service. Do you agree with its introduction
as described...yes or no and why? Email ACBRO or if you prefer snail mail, address your letters to, ACBRO, Packet Radio Issue,
PO Box 170, Walkerville, S.A., 5081. Alternatively you may fax ACBRO at (08)
8285 6883.
PACKET RADIO FOR THE BEGINNER
Recently the ACA decided, against the will of the majority of CBers, to
allow telemetry data modes to be used on UHF CB. This in itself was not a huge
problem, but the ACA also decided to stop normal voice use of channel
22 and 23 and allocate these channels for telemetry transmissions only.
As far as we hobbyist CBers are concerned, this has effectively limited UHF CB
to 38 channels instead of 40. Which leaves only 20 simplex chat channels after
repeaters and calling channels are considered.
But this need not be so. In Europe CB is being used for another type of data
transmission that has been used by radio amateurs on their bands for many years.
Packet radio. It is envisaged that all European countries and many others
besides will have packet radio legalized on CB frequencies. A 1997 report by the
European Radiocommunications office recommended that all European countries
should implement CB data modes before 2008. Preferably before 2001. And so far a
few have.
If packet radio were to be allowed in Australia, on channels 22 and 23, CB
enthusiasts would be able to use these channels again and have access to a new
and interesting mode. If we are forced off channels 22 and
23 to allow exclusive data use, we might as well join the fun and not
leave these two channels completely to commercial concerns.
It is worth mentioning that packet is not a mode that will expand to fill all
the free channels. It is in the best interests of packet users to be on the same
channel as other packeteers in their area, thus only one channel need be used
for packet, nationally. Packet is very economical on frequency spectrum; many
users can use the same channel at once.
So what is packet radio?
It is a means of sending data messages to each
other using a normal FM voice radio and a computer.
Is it complicated and beyond the casual hobbyist?
No, not at all. Anyone who likes to dabble
with computers will have no problem getting to grips with packet. And by dabble
I mean, if you can figure out how to send an email, packet will be no worries to
you.
Is it expensive?
No. You may need to buy a TNC but they are not
too expensive these days as they have been around for a long time on amateur
bands and are cheap second hand. There are programs around which use the
computers sound card as a TNC now, this is the cheaper route but requires
specific software.
So how do I get going?
Well, you will need a UHF CB, which is set up
ready to go. A computer, any age or type will do, an old amiga or 286 will even
be good enough, and a Terminal node controller or TNC. The TNC plugs into the
mic and external speaker socket of the radio and into the serial port of the
computer. The TNC is a bit like a modem between the radio and the computer. It
is worth mentioning that amateur radio TNCs are designed for a radio that still
receives audio when the mic is unplugged. If yours doesn’t do this, you’ll
need to add an extra relay, but I’ll not go into that right now.
So your CB is switched on, the TNC plugged in and the computer is running some
packet software. The software can be a simple phone modem program, or a
sophisticated program specifically designed for packet, there are many around,
but the beginner is advised to start simple. I wont go into the details of TNC
set up as they are all different, but once you have it set up, it’s a matter
of using a few simple commands. You’ll also need a callsign so that other TNCs
will recognize you; so long as you don’t pick a callsign that anyone else uses
locally there will be no problems. Maybe using your ACBRO number would be a good
idea.
So I am using the callsign JAC469, and I want to talk to my pal Pas who lives
down the road. His callsign is PAS26. So I type “connect pas26” and press
return. The TNC listens for a moment to make sure the channel is not in use and
transmits a burst of data. Incidentally, that’s why it’s called packet,
because it sends short “packets” of data a second or two long. Pas’ TNC
hears mine and sends a confirmation packet back and my screen displays
“connected to PAS26”. From then on, everything I type comes out on Pas’
screen and everything he types is displayed on mine. My TNC only listens for
Pas’ packets, and waits for the channel to be clear before replying. This way
several people at once could be using the same channel to talk to their pals and
not even be aware that there are others on that channel. The data bursts pass by
each other in the spaces between “overs”. Clever eh? Also it is impossible
to receive corrupted data. Once the packet has been sent, the sending TNC waits
for a quick conformation packet from the other end before continuing, if it
doesn’t receive the confirmation it resends the first packet until it does. So
all your spelling mistakes will be faithfully reproduced at the other end.
So big deal, we could have lifted the mic and had a regular chat, so why bother
with packet. Well this is where packet starts to show its values. Your TNC will
also have a Personal Mailbox Service or PMS. So if Pas goes out, but leaves his
radio and TNC switched on, the TNC will take messages for him. When I connect to
him and find he isn’t there, I can reconnect to his PMS and leave a message.
When Pas arrives home and sees a flashing light on his TNC indicating he has a
message he can read it and if I have gone out by then, he can leave a message on
my TNC for me. It’s like having an answering machine on your CB.
But there’s more. TNCs can also be used to digipeat. Do what? Digipeat! Lets
say my other pal Bob, who uses the callsign BOB123 lived to far away from my
house for me to hear, but Pas can hear him. I could use Pas’ TNC as a
repeater. I would type, “connect bob123 via pas26”. This would first connect
to Pas’ TNC and use his CB to relay the connection to Bob. Then Bob and I
could have a contact, or if Bob weren’t in, I’d leave a message for him.
Most TNCs allow digipeating through up to eight TNCs, although the contact would
be very slow if so many relay stations were used.
Now this is all fairly basic one to one stuff. On the amateur bands there is a
worldwide network of nodes and Bulletin Board Systems or BBSs. And in several
countries in Europe there are countrywide packet networks on CB. A node is an
unattended repeater station, usually placed at the top of a hill. This allows
packet stations to work much further than they could normally. A bulletin board
is like a huge personal mailbox that can be accessed by anyone and open messages
left on them for everyone to read. The nodes and BBSs are used as a forwarding
system to send the open messages round the country to display them on every BBS.
And personal mail can be routed along with it. Say Bob moved to Perth, which is
the other end of the country to me. If Bobs local BBSs callsign was PERBBS, I
could connect to my local BBS and send a message to “bob123 @ perbbs”. My
local BBS would know the forwarding route to PERBBS (because BBSs are clever
like that) and off it would go, jumping from one node to another all the way to
Perth where it would arrive at PERBBS for Bob to read next time he connected to
PERBBS. Or if Bob had set up auto forwarding, PERBBS would leave it on his PMS
to read when he gets home.
Now a national network is an ambitious undertaking, which would take a long time
to develop, but there is nothing stopping it happening, it has in several other
countries. And fairly complex networks could easily establish themselves around
the cities and major population centres. And even if no network exists in your
area, every TNC that is left switched on can be used to digipeat and thus every
individual with a packet station adds to the local network. Packet is very much
a community mode.
As time marches on more and more modes are becoming cheaply available to the
radio hobbyist. Most take a lot of band space or lengthy transmissions and would
be difficult to fit into an already overcrowded CB band. But packet radio is not
one of those modes. CBers could easily utilize it. Packet is fun, useful and
even educational. I’ve used it for years now and cant understand why nobody
has wanted to legalize it on CB before now, but with the two enforced data
channels this is the perfect time to add another mode.
Jack,
ACBRO 469
If you would like further reading on Packet Radio operation please visit the
following website, though it is an American based web site it provides pertinent
information about Packet Radio:
INTRODUCTION
TO PACKET RADIO
When submitting your thoughts and opinions on
this issue, please remember that it pertains to an introduction of Packet Radio
on channels 22 and 23 only on the UHF CB Band.
Currently, ACBRO are not necessarily advocating any proposal or an introduction
of Packet Radio to the CBRS but are introducing the topic for discussion
purposes only.