[aprssig] APRS on UHF?

Tom Hayward tom at tomh.us
Wed Nov 26 23:26:18 EST 2008

>> The alternative VHF APRS network (144.35)
>> in western Washington supports both 1200
>> baud and 9600 baud. The plan is to phase
>> out 1200 baud support once all users convert
>> to 9600 baud.
> What?
> What about travelers?
> What about visitors?
> What about the national APRS channel of 144.39 everywhere in the north american continent?

144.39 is still available, albeit there is a fair amount of QRM to
deal with so your packet may not get through. Granted, if you're
traveling or don't care if all of your packets are heard, 144.39 still
works just fine. The same hill here has 144.35 (1200 and 9600 baud),
144.39 (1200 baud), and 440.875 (9600 baud) digipeaters--we not trying
to leave anybody out.

> What about the objective of APRS for visualizing the surrounding tactical situation?
> Tell us more about how you are supporting APRS for general ham radio, and not just a small clique of users?

144.35 is advertised as a low-power tracker frequency. There is enough
50 watt QRM in western Washington that low powered trackers aren't
always heard. My APRS goal is sharing tactical information between SAR
teams. This is much easier to accomplish on a quieter frequency.

The alternate frequency has its own digis and igates, so messages can
flow between networks. We have experimented with cross-digipeating
local information between channels.

The primary goal, as I see it, of the alternate frequency is to
experiment and encourage a switch to 9600 baud. We've reached the
saturation point of 1200 baud, and if the goal is to share all
tactical information for the area, we need to find a more efficient
way to do it. 9600 baud seems like the most efficient way to do this.

Your local information initiative on 144.38 1200 baud APRS is working.
Working so well in fact that we've overloaded the channel in the area.
So we're solving it like hams with innovation and experimentation.


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