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Transmitter Hunt Using GPS
"Scott in Aztlan" wrote in message ... Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander ---snip--- Can someone point me in the right direction? Just follow the strongest radio signal. ;-) |
"Scott in Aztlan" wrote in message ... Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander ---snip--- Can someone point me in the right direction? Just follow the strongest radio signal. ;-) |
Scott in Aztlan wrote:
Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander around, you collect positions from the GPS and signal strength values at those positions from the radio; your goal is to crunch these data points into an estimate of the transmitter's location. Clearly you could use trilateration with any 3 of the data points and get an estimate, but how would you make use of the fact that you have an arbitrary number of data points? If I understand clearly you are interested in locating an RF source which has nothing to do with GPS by using RF receivers and nondirectional antennae. Trilateration is only of value if one can establish accurate timing distances, synchronized between all receivers. If you used directional RF antennae, then, in conjunction with receiver positions determined by GPS receivers, you could simply triangulate to estimate the RF source position. Isn't there some algorithm which, the more data points it is given, the better its estimate gets (similar to the way you can average a series of position readings taken from a stationary GPS receiver to compensate for the effects of SA)? Of course SA was permanently discontinued more than three year ago. Interagency GPS Executive Board (IGEB) - Special Statement http://www.ostp.gov/NSTC/html/pdd6.html http://www.igeb.gov/sa.shtml Presidential Policy & PRESIDENTIAL DECISION DIRECTIVE NSTC-6 http://gps.faa.gov/gpsbasics/PresPolicy-text.htm http://www.peterson.af.mil/GPS_Suppo...ts/gps_pdd.htm Selective Availability http://gps.faa.gov/gpsbasics/SA-text.htm Joint Program Office http://gps.faa.gov/gpsbasics/JPO-text.htm |
Scott in Aztlan wrote:
Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander around, you collect positions from the GPS and signal strength values at those positions from the radio; your goal is to crunch these data points into an estimate of the transmitter's location. Clearly you could use trilateration with any 3 of the data points and get an estimate, but how would you make use of the fact that you have an arbitrary number of data points? If I understand clearly you are interested in locating an RF source which has nothing to do with GPS by using RF receivers and nondirectional antennae. Trilateration is only of value if one can establish accurate timing distances, synchronized between all receivers. If you used directional RF antennae, then, in conjunction with receiver positions determined by GPS receivers, you could simply triangulate to estimate the RF source position. Isn't there some algorithm which, the more data points it is given, the better its estimate gets (similar to the way you can average a series of position readings taken from a stationary GPS receiver to compensate for the effects of SA)? Of course SA was permanently discontinued more than three year ago. Interagency GPS Executive Board (IGEB) - Special Statement http://www.ostp.gov/NSTC/html/pdd6.html http://www.igeb.gov/sa.shtml Presidential Policy & PRESIDENTIAL DECISION DIRECTIVE NSTC-6 http://gps.faa.gov/gpsbasics/PresPolicy-text.htm http://www.peterson.af.mil/GPS_Suppo...ts/gps_pdd.htm Selective Availability http://gps.faa.gov/gpsbasics/SA-text.htm Joint Program Office http://gps.faa.gov/gpsbasics/JPO-text.htm |
Assuming your concept was valid, i.e. signal strength was a function of distance by
some formula (inverse square), the approach to follow is called least squares. Look around for additional info with that terminology. - jlw Scott in Aztlan wrote: Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander around, you collect positions from the GPS and signal strength values at those positions from the radio; your goal is to crunch these data points into an estimate of the transmitter's location. Clearly you could use trilateration with any 3 of the data points and get an estimate, but how would you make use of the fact that you have an arbitrary number of data points? Isn't there some algorithm which, the more data points it is given, the better its estimate gets (similar to the way you can average a series of position readings taken from a stationary GPS receiver to compensate for the effects of SA)? Can someone point me in the right direction? Thanks! -- Friends don't let friends shop at Best Buy. |
Assuming your concept was valid, i.e. signal strength was a function of distance by
some formula (inverse square), the approach to follow is called least squares. Look around for additional info with that terminology. - jlw Scott in Aztlan wrote: Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander around, you collect positions from the GPS and signal strength values at those positions from the radio; your goal is to crunch these data points into an estimate of the transmitter's location. Clearly you could use trilateration with any 3 of the data points and get an estimate, but how would you make use of the fact that you have an arbitrary number of data points? Isn't there some algorithm which, the more data points it is given, the better its estimate gets (similar to the way you can average a series of position readings taken from a stationary GPS receiver to compensate for the effects of SA)? Can someone point me in the right direction? Thanks! -- Friends don't let friends shop at Best Buy. |
Scott in Aztlan wrote: Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander around, you collect positions from the GPS and signal strength values at those positions from the radio; your goal is to crunch these data points into an estimate of the transmitter's location. Clearly you could use trilateration with any 3 of the data points and get an estimate, but how would you make use of the fact that you have an arbitrary number of data points? Isn't there some algorithm which, the more data points it is given, the better its estimate gets (similar to the way you can average a series of position readings taken from a stationary GPS receiver to compensate for the effects of SA)? Can someone point me in the right direction? A system for integrating GPS with direction finding has been out for a few years now. Utilizing Doppler Direction finding equipment, the heading of the Doppler array, along with the Lat Long of the monitoring station is sent in a packet burst and superimposed on a map. When you have 2-3 of these stations submitting this data in real time, you get a practically instantaneous triangulation on the location of the transmitter. The Agrelo Doppler units that were available several years ago, had this capability. Andy WD4KDN -- An armed man is a citizen, an unarmed man is a subject. An armed society is a polite society. |
Scott in Aztlan wrote: Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander around, you collect positions from the GPS and signal strength values at those positions from the radio; your goal is to crunch these data points into an estimate of the transmitter's location. Clearly you could use trilateration with any 3 of the data points and get an estimate, but how would you make use of the fact that you have an arbitrary number of data points? Isn't there some algorithm which, the more data points it is given, the better its estimate gets (similar to the way you can average a series of position readings taken from a stationary GPS receiver to compensate for the effects of SA)? Can someone point me in the right direction? A system for integrating GPS with direction finding has been out for a few years now. Utilizing Doppler Direction finding equipment, the heading of the Doppler array, along with the Lat Long of the monitoring station is sent in a packet burst and superimposed on a map. When you have 2-3 of these stations submitting this data in real time, you get a practically instantaneous triangulation on the location of the transmitter. The Agrelo Doppler units that were available several years ago, had this capability. Andy WD4KDN -- An armed man is a citizen, an unarmed man is a subject. An armed society is a polite society. |
What your describing sounds alot like GeoCaching.
An already-established sport which I have participated in. Finally, most if not all of the participants in this sport also seem to be a younger and/or a college educated clientele. More about it at the link(s) below: http://www.geocaching.com/ http://www.mdgps.net/ http://gpsinformation.net/ "Scott in Aztlan" wrote in message ... Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander around, you collect positions from the GPS and signal strength values at those positions from the radio; your goal is to crunch these data points into an estimate of the transmitter's location. Clearly you could use trilateration with any 3 of the data points and get an estimate, but how would you make use of the fact that you have an arbitrary number of data points? Isn't there some algorithm which, the more data points it is given, the better its estimate gets (similar to the way you can average a series of position readings taken from a stationary GPS receiver to compensate for the effects of SA)? Can someone point me in the right direction? Thanks! -- Friends don't let friends shop at Best Buy. |
What your describing sounds alot like GeoCaching.
An already-established sport which I have participated in. Finally, most if not all of the participants in this sport also seem to be a younger and/or a college educated clientele. More about it at the link(s) below: http://www.geocaching.com/ http://www.mdgps.net/ http://gpsinformation.net/ "Scott in Aztlan" wrote in message ... Suppose you were participating in a search for a hidden radio transmitter, only instead of the usual radio receiver with a directional antenna you have a receiver with an omnidirectional antenna and a GPS receiver. As you wander around, you collect positions from the GPS and signal strength values at those positions from the radio; your goal is to crunch these data points into an estimate of the transmitter's location. Clearly you could use trilateration with any 3 of the data points and get an estimate, but how would you make use of the fact that you have an arbitrary number of data points? Isn't there some algorithm which, the more data points it is given, the better its estimate gets (similar to the way you can average a series of position readings taken from a stationary GPS receiver to compensate for the effects of SA)? Can someone point me in the right direction? Thanks! -- Friends don't let friends shop at Best Buy. |
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