[aprssig] APRS in daily use

[Stephen H. Smith]

On 2/23/2011 9:06 AM, djhuff at rockwellcollins.com wrote:
>
> 4. Low tech lojack.  I have had to put a portable repeater up for an event, 
> so I attached a small tracker to it, to report its known position.  When the 
> event was over people asked if it was picked up yet, so I went to the map, 
> and looked, since it was still beaconing, it was a reminder that the stuff 
> was still there.

Actually APRS is much higher tech than LoJack!

LoJack uses what is essentially a pager receiver to turn on a low-power 171 MHz 
transmittter on demand. There is no GPS data transmitted -- just a 1-2 watt 
transmitter beaconing a 5 digit unit ID.     The cops are sent on a T-hunt 
using a doppler-scan-type DFing antenna.  Inside the car, all they have is a 
compass-rose heading display that points to the direction of the signal and a 
bar graph relative signal strength display. (If you've seen a police car with 
four VHF whips in a square array on the roof, you've seen a LoJack tracker unit.)

No maps showing the exact location of the suspect car.   With an OT-2 and nuvi 
350, (not to mention a D700 with a laptop with APRS software) we have FAR more 
capability to locate a vehicle.


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Stephen H. Smith    wa8lmf (at) aol.com
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