[Coco] Ham Radio

[John E. Malmberg]

jdaggett at gate.net wrote:
> John
> 
> I downloaded the APRS protocol document and looked at it. It appears that APRS 
> uses only the AX.25 UI frame. It appears that only 1200 baud is supported, maybe 
> 2400, for VHF/UHF. It is a tight squeeze to get 9600 baud in a VHF channel width of 
> 15KHz. The AX.25 UI frame is a max of 332 bytes and interesting that the color 
> pallette for the map symbols is 16 colors!

You could probably get a COCO to directly function as a 1200 baud TNC, 
but it really would only be useful to show off programming skill.


A 1200 Baud AX.25 modem (TNC - Terminal Node Controller) can be had used 
for about $25.00 U.S. or less.  As soon as internet access speed got 
above 33K on average, packet radio for message passing and rag-chewing 
basically died off.  In many places, the backbone links are gone, but 
there are internet tunnels that some people can take advantage of.  The 
upgrade to 9600 baud is too expensive for most people.  It requires 
modifying most radios to use it.


> Personally I think that APRS is an overkill for general traffic. I can see where it can 
> catch on though. With all the different packet switches and the meriad of 
> &^^&%$tors that have proliferated amature radio, APRS is considerably simpler. AN 
> old 286 computer, a 1200 baud TNC and a VHF radio and away you go.

As the usefullness of 1200 baud packet declined, there was a glut of old 
VHF radios and packet modems.  They are being recycled in the APRS 
usage.  The only expensive addition for the mobile users is a GPS for 
real time tracking for coordinating public service and emergency work.

As word gets around that the FCC has removed the barrier to using off 
the shelf 802.11 stuff, maybe a new backbone will start showing up to 
replace the old one.

A VHF radio suitable for packet radio can also be found for about $25.00 
  U.S. or less.  You may need to buy crystals for the local frequency.

A suitable antenna can be purchased cheaply, or you can make some very 
good ones out of readily available materials.

There is still some AX.25 packet running here, but I have not seen any 
real traffic.

There is a variant of the AX.25 protocol known as TheNET, for network 
communication.  I seem to be currently just out of range of the closest 
node with my QRP radio on an internal antenna.

Also there are DX clusters that report where to find DX stations.  This 
along with the APRS seem to be the most active uses of AX.25 in this area.

-John
wb8tyw at qsl.network
Personal Opinion Only