[aprssig] 9600 BAUD UHF APRS

[Bob Bruninga]

> We have been doing a little 9600 baud
> APRS on 438.975 for several years though.

Won't work in Baltimore. 439.250 is the powerful output of the ATV repeater, so 438.975 is right in the middle of the lower vistigial sideband. 

But the Baltimore ATV repeater is unusual,  The more common arrangement is to have 439.250 be the user INPUT to the ATV repeater, and so having mobiles tansmitting on 438.975 would be unwelcome indeed! since it would hit  all atv activity ALL the time.

But I just realized while looking for a freq, we could be willing to concede that we only need a NATIONAL MOBILE 9600 baud INPUT channel as the minimum.  In areas where there are problems with it being an output, an output could be on a different local channel.  That FREQ OBJECT could be beaconed on 144.39 to all in range to alert them were to find the high speed output.

just some thoughts.

Bob, Wb4APR

>   In Southern California, 440.800 is a repeater input
>   (445.800-), and 445.925 is 5 kHz off of a repeater
>   output (445.920-).  Unfortunately, neither of those
>   proposed frequencies will be usable in Southern
>   California.  We have been doing a little 9600 baud
>   APRS on 438.975 for several years though.
>
>   73
>   Phil - AD6NH
>   www.aprs2.net
>   www.aprsca.net
>
>   David Dobbins wrote:
>
>     Our experimentation with 9600 baud APRS in the
>     Puget Sound region for the past year + shows it
>     works, and works great. We have a dedicated 9600
>     baud APRS infrastructure growing on 440.800MHz and
>     will continue our development.
>     In a recent message with Bob WB4APR, re the
>     445.925 frequency.... he is recommending that as a
>     UHF voice coordination frequency for APRS, rather
>     than a data freq.
>     We will continue checking with our regional
>     coordination authorities in hopes of formally
>     designating 440.800 for 9600 baud APRS. In
>     reviewing the WWARA band plan for UHF, 440.800
>     does not fall into any category for other use, so
>     works well with our plans.
>     Feedback appreciated..... will 440.800 work
>     elsewhere in the country? We're hoping for a
>     single UHF frequency to continue development of a
>     9600 baud infrastructure.
>     For those of you in larger metro areas, when you
>     listen to 144.39 and all the packet activity, do
>     you seldom hear a pause between packets? If so,
>     you should pursue UHF 9600 baud development where
>     the packets are much shorter and propagation seems
>     to be working pretty darn good. We're having lots
>     of success with both D700/D710 and KPC-9612 w/Icom
>     or Alinco 9600 data radios for TNCs.
>     We also have a very successful 9600 baud VHF
>     infrastructure growing on 144.35 in the Puget
>     Sound region.
>     There's lots of room for more informational data
>     on a 9600 baud system, and our guru's are busy
>     exploiting that now.
>     Dave K7GPS
>     NWAPRS Lead Coordinator
>
>      ----------------------------------------------
>
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