[aprssig] 9600 APRS

Wes Johnston, AI4PX wes at ai4px.com
Sun Feb 27 20:42:13 EST 2011

Yes, many new rigs are 9k6 ready, but they still have horrendous txdelays.
Kantronics did make a good little dataradio years ago that had something on
the order of 40ms (???) txdelay.    And we can really appreciate 9k6 for
longer TCP type packets... packets >200 bytes.  But for our little onsie
twosie packets of 30 to 50 bytes, it's just not worth the effort.

Moving an aprs digipeater to 440 would be great, 1200 baud sure.  What would
be cool would be to have 144.39 and a 70cm frequency bridged at 1200 so that
it didn't matter which freq you used, you'd see everything on your local
digi on either frequency.  The purpose of this would be to allow mobiles to
run 70cm when they used 2m voice or vice versa.

Skipping right along, on Bob's random text files from years ago, one really
stuck with me.  It was running data output on the input frequency of a
repeater.  This would be prefect for 9k6 distribution of weather products.
Thing is that today many voice repeaters have COR gated PL tone outputs.  So
we could transmit 9k6 on the output of the repeater with no PL tone for
HOURS.  Think of all the time that a given repeater is inactive thru the
day.  Of course once a voice user started on the repeater, the data would
pause.  Now if the voice users run PL tone decoders, they'd never know it
was there!  If they didn't run PL decode, they'd hear quiet static, not
annoying BRAAAAPPPPS.  Now what data would you put on that?

"Language shapes the way we think, and determines what we can think about."
-- B. L. Whorf

On Sun, Feb 27, 2011 at 09:30, ml41782 <ml41782 at yahoo.com> wrote:

>  Original MSG
> This is a savings of 27ms. based on his numbers. I have seen numbers
> shorter and longer than 150ms for keyup. This doesn't sound like alot of
> savings but every little bit helps.
> 9600 on VHF ?  I have never really seen this work on even on packet
> I have seen 2400 & 4800 on VHF but a true 9600 no because of bandwidth
> restrictions.
> 9600 on UHF  yes it does work.
> injection points and output points
> 9600 input requires more drive than 1200 and is injected past the audio amp
> befor the exciter because of bandwith limits by filtering.
> 9600 output is at the dicriminator before the filtering of the amplifier of
> the speaker.
> 1200 input is at the microphone
> 1200 output is at the speaker.
> For the amount of data that is pushed we should drop back to 300bps, 150bps
> or slower. That is all that is used.
> If you have a D700 you know of the blanking that takes place when the APRS
> transmits. and if you are in a conversation on the other side of the radio
> it gets that blanked out space while APRS is transmitting.
> Move that up to 440 and run APRS at 9600.  no blanked out conversation on
> or UHF.  Is that an improvement ? Yes.
> I don't know how the D710 or the other radios deal with this but the ideal
> here is to improve on systems and move forward out of the dark ages. I only
> see patches here and not fixes. There is only so much that we can get out of
> one frequency.  If you want to beat a dying horse then stay at 1200 and use
> multiple frequencies. One for travellers 144.390 giving local repeater info
> and digi's. 145.390 for local service and they are both tied to Igates and
> both pulling data that they feel is needed but not everything.
> The points are different to get the needed speed. The manufacturers are
> putting them into the newer radios and you can adapt them to older rigs.
> I have been experimenting in Virginia for years with 110, 300, 1200, 9600
> and up to 128k. The higher speeds are the direction we should have gone in
> years ago. I have 9600 APRS up in my area of virginia. unfortunately no one
> else in the are has used it but myself. I will be expanding it this spring
> and see if there is more interest.
> Should they mix information directly between bands ? Some of it yes the
> resto of it no. Keep them separate and let the data flow in and out of the
> IGATE. let the individual system put the data from the APRS IS servers.
> These messages are long enough without 20 messages behind them for a simple
> answer.
> Mike K4MQF
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