[aprssig] APRS on all Radios!!!!
bruninga at usna.edu
Sun Aug 17 15:28:34 EDT 2008
> Wouldn't the 120-Hz subcarrier still be
> problematic for phase modulated rigs?
I didnt think so, since here are guaranteed transistions evry bit independent of the data.
> Why not simply use something like MIC-E?
>[and] something like a 4-kHz [PSK31] subcarrier...
> transmitter for the downlink?
> build and market a kit for the end user
> MIC-E/PSK-31 gadget?) What could be
I was going to endorse this as another good approach except for one thing. The Mic-E to be done right has to be installed so that it is inseries with the existing Mic-PTT. If this is not done, all the advantages of PTT-tail operation are lost as a much much longer TXD and lockup are reuired even if the PTT is dropped evern for milliseconds. It is this cutting of the mic-cord that is one of the issues that has prevented Mic_E from really taking off.
A sub-audible dongle plugged into the radio's DIN connector runs completely independently of normal operation, so that is why I thought it was a more practical approach...
But the idea of "super-audible" solves the problem of the combination of PL and this APRS DPL on the same channel.
----- Original Message -----
From: "Bob Bruninga " <bruninga at usna.edu>
To: "'TAPR APRS Mailing List'" <aprssig at lists.tapr.org>
Sent: Sunday, August 17, 2008 9:28 AM
Subject: Re: [aprssig] APRS on all Radios!!!!
>> Needs careful thought/design.
>> This is a problem for Phase modulated rigs
>> because of ... low freq components...
> Could it simply be PSK-31 encoded? What is the lowest carrier tone that
> can carrry PSK-31? Some APRS dongles already are starting to decode
> PSK-31. And with say a 120 Hz carrier, it would seem that it would remain
> sub-audible? We would of course add CRC checks to make each info packet
> Bob, WB4APR
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