[aprssig] Standard PL Tone for 144.39

[Bob Bruninga]

> I keep looking at the message portion:  
> PL 100, PL <something else>, 
> PL <not either of those> .
>
> Is there a standard tone frequency?  

Yes, all APRS mobiles (that can, or want to be available for calls) operate with a CTCSS 100 on 144.39.  This is called APRS Voice Alert.  Google for it.

They keep their 144.39 channel volume UP but muted with CTCSS-100 so that they dont hear packets, but can hear a local simplex VOICE call with PL 100.

Maybe you are seeing all the other local Voice repeater frequencies that are also locally output on APRS.  These show traveelers what reecommended voice reepeater they are in range of.  Every APRS digi is supposed to output once every 10 minutes an OBJECT packet that displays the frequency of the locally receommended voice repeater.  These will all have different PL's.

Google for APRS Local Info Initiative and see if it comes up.
or maybe local voice repeater initiative...

Bob