Triangulation with Stamp

Benj

Hello,

I am looking for some "getting started" information on how to do some triangulation with a stamp. For example, in an open field I would like to set up three fixed point beacons and then be able to carry around a unit that will, through the use of geometry be able to determine where the unit is, relative to the beacons. I am not looking to do time of flight calculations, but simply based upon the three angles be able to determine the unit's location. I would like a range of maybe 150 feet from any beacon, but am not sure what to use for transmitters and receivers. The unit would need to be able to determine the compass angle of each beacon and I would also need some ideas there. I was thinking of some type of spinning radar type dish that would measure signal strength to determine where the beacon is located, but if there are any easier ways of doing it, I am all ears.

Any help is appreciated.

Benj

Mike Green

This is a pretty difficult problem. I suspect you will not be able to get an adequately focused small beam for positional accuracy at that range unless you stick with a modulated light beam and some kind of setup with an unobstructed line of sight to the beacons probably using a simple telescope on a rotating platform. I'm not sure how you'd make the beacons so that they'd have a broad "wedge" of coverage. It may be easiest to have the beacons use a rotating telescope as well with the beacon's telescope position encoded on the beam for the unit to decode and use once it acquires the signal.

erco

Outdoors in broad daylight, I doubt if you·could reliably·sense any type of light source or reflection except a hi-power laser. Dangerous.

At night, you might have limited range with low power lasers or lens-focused IR beam. You can buy 5-watt IR luxeon stars on ebay right now. http://cgi.ebay.com/5-Watt-Infrared-IR-LED-Night-vision-camera-Flashlight_W0QQitemZ250248985080QQihZ015QQcategoryZ66954QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

A few years ago I hatched a fairly·obnoxious·method to roughly triangulate an autonomous·blimp's position over a football field. Hi-power audio. Place 3 or more·LOUD intermittent tone burst sources in precise locations around the field. Sort of an audio GPS.·Each source fires·its unique tone in a carefully synchronized pattern (as simple as ABCABC...) Tone decoders on the ship know the individual tones and, based on variations in the timing intervals between tones, factoring in the speed of sound, one could triangulate the ship's location. Theoretically... Of course, ambient sound and echos would cause problems, and the sounds generated would be have to be loud and objectionable. It would only work on a fairly large scale, where the speed of sound variations could be measured accurately.



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·"If you build it, they will come."

tedbeau

There was a lengthy discussion along these lines a little while back. Check out this thread:

http://forums.parallax.com/showthread.php?p=721326

iamdenteddisk

I would suggest sound, it would work reguardless of light and the support devices simple to implement,I have been working on this too, my problem isnt how to do it but how to do it with this microcontroler ,each of the three points would be a single seperate tone from the opposite two emmited by a unidirectional spkr. the reciver should be a parabolic microphone wich is insulated from behind to block hearing what is behind it meaning if the tone emmited behind is heard it is echo, the reciver should be handheld or automated to allow movement aswell as rotation the emmited tone should be higher than pitchrange heard by living organizims so you dont break glass or make dogs madd, as the distance you want to cover will require a loud tone so multiple amplifiers will be required.
first detect tone,to know wich direction you are pointed then evaluate the volume of each tone while the reciver is revolved to know your distance from each emitter/beacon .
the volume of emmiters will have to be callibrated to get a useable tone at maximum distance then set all to that same volume if all is done this way and the insulation on the reciver is good enough then no matter what direction you point the reciver it will pickup two loud tones of varrying volume. testing the volumes will tell you with some certinty of direction the loudest at that point will be closest to true or streight alignment the volume of the lesser tone at this point will tell you how far off alignment you are with its emmiter/beacon the third tone will still be present but will be verry small and considered echo/not of importance untill reciver is rotated
for more info look into radar/sonar remembering the wavefront is round and a parabolic microphone recives only from one direction "infront".
and if it helps too, some of the parallax boards can support gps and if the reciver part of this post is aware of gps it can also be used to calculate the gps point of each emmiter still this is only two deminsional triangulation but if the reciver can raise and fall from allignment with emmiters it can then be a true 3 diminsional triangulation like that used by batt's in flight or a survayer's transit.

·Also I think I'm gonna go the cheap route there is a "hunting dog tracking system in cabella's sportmans catalog for $30 it comes with 2collars and 1 reciver all can have freq changed the reciver has 5 led's four aranged in a cross to indicate direction and 1 to depict doppler blip or flash" works to 2.5 miles·,for·my project·I will need two sets to have the three beacons 1 extra and an extra reciver wich might be·needed if·I screw somethin up modifing it to work with my board.

Post Edited (iamdenteddisk) : 6/1/2008 9:15:47 AM GMT