[aprssig] "Smart" vs. "dumb" trackers

[SARTrack Admin]

On 23/06/2014 17:03, Stephen H. Smith wrote:
> On 6/23/2014 10:03 AM, SARTrack Admin wrote:
>> The tinytrak-3 connected to a (cheap) handheld radio will check for an
>> open
>> squelch (any noise) before transmitting.
>
> Except that this is not a positive carrier detect; i.e COR. All it does
> is sense audio energy coming from the radio's audio-out.   It gets
> fooled by dead carriers or under-deviated voice signals on the channel
> into thinking the channel is clear.

Correct, but how often do you have 'dead carriers' of voice data on the 
APRS frequency? It basically always is a APRS signal, so it works quite 
well.

>
>>
>> The TinyTrak-4 has even a full decoding capability.
>> http://www.byonics.com/
>
> But you still need (in addition to the handheld and TT4) :

The original question was about Trackers. Not a full two-way messaging 
system.

Have a look at my original design, using a VX-170 (or Type Approved 
radio in my final design), GPS chip and TinyTrak3 in a small box, and 
powered from the radio. This setup runs for 12 hours, every 30 seconds 
TX (used on a special VHF frequency). You can also use a very cheap 
Chinese radio on the HAM frequencies.

http://www.sartrack.co.nz/Trackers.html

Bart

-- 

SARTrack Developer and CEO