[aprssig] indoor tracking. RFID

Gerry Creager N5JXS gerry.creager at tamu.edu
Wed Jun 1 09:24:41 CDT 2005

The relative GPS accuracy is gonna be affected by antenna obscuration 
and constellation visibility.  If you could guarantee all receivers had 
similar constellation exposure and the same satellites, it's pretty 
good.  With the Motorola receivers, you can specify "high 4" mode and 
solely get the 4 satellties highest in the local sky, which would make 
this work somewhat better.

A SWAG for relative accuracy would be on the order of 1-2 meters, 
assuming the receivers are pretty much seeing the same satellites, the 
antennas are all positioned the same, etc.  A more conservative estimate 
is about 6 meters for accuracy, period.


scott at opentrac.org wrote:
> I was thinking of doing something like this with Zigbee transmitters for
> tracking paintball players.  I'm curious what the relative GPS accuracy is -
> in this case it doesn't matter so much that you know exactly where you are
> on the planet, you just want to know where you are relative to everyone
> else.  And since everyone's within an area of 20 acres or less, I expect a
> lot of their errors would be the same.
> Scott
> N1VG 
>>-----Original Message-----
>>From: aprssig-bounces at lists.tapr.org 
>>[mailto:aprssig-bounces at lists.tapr.org] On Behalf Of Brian B. Riley
>>Sent: Wednesday, June 01, 2005 6:38 AM
>>To: TAPR APRS Sig; Bob Bruninga; wes at kd4rdb.com
>>Subject: Re: [aprssig] indoor tracking. RFID
>>The simplest implementable solution would be something Bob 
>>espoused long ago, tie a PIC/MIM unit to a 433 MHz key  fob 
>>transmitter and setup up vicinity tracking digis. The 'new' 
>>technology here would be the 'digi' ...
>>We need to be able to put something like this with the 433 
>>receiver and a linking channel transmitter into a PIC or 
>>ATMEL package (actually this looks like a perfect application 
>>for John Hansen's TNC-X!).  Its kinda like a wedding " ... 
>>something old, something new ..."
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Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University	
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
Page: 979.228.0173
Office: 903A Eller Bldg, TAMU, College Station, TX 77843

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