NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/aus/radio/1001

Internet Message Format | 1993-01-28 | 6.3 KB

Path: sparky!uunet!munnari.oz.au!metro!usage!sserve!hhcs.gov.au!makinc
From: [e-mail] (Carl Makin)
Newsgroups: aus.radio
Subject: Re: Citizens Band Packet Radio on 70cm
Message-ID: <[e-mail]>
Date: 27 Jan 93 09:46:29 +1100
References: <[e-mail]>
Organization: Aust. Dept. Health, Housing and Community Services
Lines: 126



In a quick side note, who is gating this newsgroup through to
Fidonet?  (not that I mind. :-)

In article <[e-mail]>, [e-mail] (Peter Berrett) writes:

>  m> Now since the TNC will be connected to a type approved radio, it
>  m> will probably have to be type approved too.  This means the
>  m> manufacturers will have to submit their TNC designs and hardware
>  m> to DoTC type approval.  An expensive business.

> Hmmmm dissection time! Now first the TNC. A Baycom modem can be obtained from
> the Melbourne Packet Radio group with software for as little as $125. As for

Ok, the Baycom modem available from the MPRG is NOT type
approved.  Type Approval requires that an example of the device
be submitted to DoTC along with the payment of a fee.  That fee
is NOT small.  (I don't know what that is though, can anyone tell
me the correct figure?)

> the question of tranceivers, yes the equipment is not available at present
> however once the standards were laid out it would not be difficult for
> manufacturers to change the circuit designs of current radios to suit packet.
> Granted the DOTC approval would be a hitch but current cb manufacturers do it
> now already so it must be possible.

It's possible but the cost of Type Approval is amortised over a
large production run.  I can't see similar economies of scale
being applied to a "packet" facility.

> If say the cb band was on vhf instead, then
> current handheld for vhf area are available for as little as $299 new. The
> modification for packet use and frequency change would not be that difficult.
> So the total cost to the user would be more in the order of between $425 and
> $500 which for many computer users would be acceptable.

Well you can forget any sort of allocation in the VHF spectrum
however, if you could work up the support, you might get
something in the UHF spectrum.  Costs are a little higher but not
out of reach of your business user.

>  m> Now, lets look at actually using this CB data service.  You are
>  m> restricted to using 1200 baud HALF DUPLEX with, at best, a
>  m> throughput of around 80 CPS (taking into account timing delays,

> Yes its slow but hence the need for a large number of channels.  The greater
> the number of channels and the lower the power output of tranceivers combined
> with the encouraged use of directional antennas results in less collisions,
> less interference to third parties and less dogpiles.

Nope, actually you get more collisions because the "hidden
transmitter" problem nails you.  When multiple stations are using
directional antennas on a single frequency the chance is higher
that the transmitting station will hear only one of the stations
in an existing link and transmit over the top of the other.

The only way to eliminate the hidden transmitter problem is to
not have eny hidden transmitters, ie use a repeater of some sort.

>  m> Compared to Fidonet BBSs and similar technology the Packet BBS
>  m> system is unfriendly, slow, and lacking in features.  There isn't
>  m> even a standard file transfer protocol.  There are a number of
>  m> protocols around such as YAPP and the BAYCOM protocol but XMODEM
>  m> and ZMODEM and their ilk DO NOT WORK properly over packet radio.

> The standard file protocol could be set down in the standards laid down by
> DOTC. These standards would also set out the bbs software to be used as normal

I see.  This is a lot of regulatory work for DoTC.  What file
transfer protocol would you use then and who would develop it?
Why should DoTC regulate it in this age of deregulation and the
freeing up of restrictions.

The point I was making in the paragraph above is that you cannot
use Packet Radio as a replacement for Telecom phone lines.  They
do not work the same way and you do not get the same final
result!

> communication software. As new products appear on-line ( and they would ) they
> could be inorporated into the standards. As for the messaging problem this
> could be overcome by the use of special interbbs channels that update on a more
> or less continuous vasis thus the volume isn't sent in one hit but gradually
> over the day. Probablt an entirely separate messaging network would need to be
> set up with gateways to fido net for specific purposes.

Eh?  Now you want to setup a complete bulletin board network!

So what you want is to trundle up to DoTC and say, "Hey, allocate
us 20 channels on VHF for a user to bbs data linking system with
another couple of VHF channels for inter-bbs linking.  By the way
we want you to regulate it and mandate standards for use in this
band and we only want to pay $18 per user to use it!"

Somehow I don't think this is a palatable suggestion.

>  m> 2) what sysop is going to provide this service for you to use?

>  Ok so it will cost $18 but that's only the equivalent of 72 phone calls

Plus the $125 for the (non type approved) 1200 baud half duplex
modem and another $500 for a radio to hook it to, plus $100 for a
decent antenna.  Yep, my yearly phone bill for my Fidonet BBS was
somewhere around that.

> (local). As for the sysop, I've already had one sysop reply that he liked the
> idea and would be prepared to hook his board up. If the standards etc were set
> up, I'm sure that there are many sysops who'd like to become involved.

Actually I think if some sort of CB style data service was
available it would be used, but not by enthused hobbiests.
There is a growing use of packet technology by businesses looking
for a cheap way to get small amounts of data from a number of
remote sites back to a central site.  Security alarms,
environmental monitoring, etc.  This is the use the majority of
equipment for your proposed Data Service would be put.


Carl.
--
Carl Makin, MVS/ESA Systems Programmer, VAX/VMS Dabbler.
Dept. Health, Housing and Community Services, Canberra, Australia.
sserve.cc.adfa.oz.au!hhcs!makinc   -   UUCP
[e-mail]           -   Internet
[e-mail]       -   Packet Radio
"I'm from the Government and I'm here to help you."