[aprssig] APRS Alt-Input digis

[Bob Bruninga]

Annapolis MD has had an alternate 144.99 input
now for several months to allow locals to get in
without QRM from out of area clobbering them.

The plan for an Alternate input digi is to encourage
all fixed stations (who know what the local input
freq is) to TX there and of course continue to receive
on 144.39.  This benefits all local users by spreading
out the input contention load on 2 channels and letting
mobiles have a better chance of getting in.

There is one additional option that can benefit users
of low power tracking devices.  And that is to
encourage the low power trackers to also operate
on that input frequency.  This way, their low power
does not have to compete with 50W mobiles and all
the other out-of area QRM also.

I think with the proliferation of low power trackers,
that it might be a good idea for all areas to consider
adding the alternate low-power trcker input channel
if they have some low power users in their area.

In Annapolis, MD, we monitored 144.99 for a week and
never heard anything, so we are using it becuase it
has the neat advantage of being +600 from 144.39.

Plesae if  you do this, check out your local coordination
of that freuqency and make sure it is not in use before
you start using it.


Good luck.

de WB4APR at amsat.org, Bob