[aprssig] Roadtrip APRS Full DUplex

Robert Bruninga bruninga at usna.edu
Sun May 13 17:00:17 EDT 2018

Next road trip using Ham Radio between cars, don't forget about the value
of Full Duplex.

Set your APRS dual band to TX on VHF and other car to TX on UHF and that
way you can talk quickly and easily.  AND you can interrupt a long winded
transmission to yell "TURN HERE"...

After a harrowing trip through NY city following my wife and daughter I
realized how valuable that would have been.
 She might be yacking and I am frantically trying to get her to turn at
the right places, but with half duplex, it is impossible.

Ill remember it next time.

I suggest the APRS operator to simply TX on APRS VHF Voice Alert on 144.39
and the other car to TX on UHF so that if the APRS operators car TX's a
packet it will not block what the other person is saying.

Set the other car to RX Voice Alert on 144.39 CTCSS 100 and to TX on UHF.
This way you have full duplex voice and don't give up APRS.

In fact, both cars can be operating APRS Voice Alert on one band and the
APRS 445.925 UHF talkback channel on the other. (Identical setups).  Its
just that one person TX's on Voice Alert and the other TX's on UHF.  Done.

AND since you are listening on BOTH, then the sex problem of full duplex
vanishes.  Any third party can contact either operator on either

I wish I had thought of this before that last road trip!
If you are doing this and looking for contacts, set your UHF to the 446.0
National Simplex.  Then you might also scare up a contact.

But you still need a 3rd radio for 52!   And this year I will be running
AutoCQ on 52.  Byonics has made me an auto-CQ'er for the trip toDayton.
It can be set to call a brief CQ once every 3 minutes (or 2 minutes, or 1
minute).  This gives 52 the same advantage as Voice Alert does for APRS.
On the 1 minute setting it only says my call.  On the 3 minute one it says
CQ 52 and the call.

The #1 problem with this device if everyone used it is the same as with
nothing more frustrating on Voice Alert than someone pinging away with the
volume turned down.  Byonics has set a timer that will time out after 30
minutes if there have been no transmissions.


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