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Triangulation

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VintageAntiq

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I've taken a few electrical engineering courses a few years back and was looking to tinker around in short distance multilateration, ie triangulation based on time differences. In high school i did a project using sonar but i guess it's fallen out of style since then because i can't find anything with that. could anyone suggest a method to triangulate and possibly some background info on the stuff i would need to make this work?
 
Triangulation is based on simple (well, simple to my teachers) trigenometry. What are you stuck on?
 
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what type of hardware would i need to make one which can pinpoint an object along x, y, z axis? in terms of signal transmitters and receivers? i can do all the coding im just not sure what the best equipment is for
 
Hook a GPS receiver with data output to modulation input of a transmitter. On remote site, receive and demodulate GPS data sent by transmit.
 
you would need a relatively high directional antenna to be able to sweep relative signal strength with decent accuracy. probably a N element yagi or log periodic for instance.

the receivers and transmitters could vary. probably VHF-UHF band you get long wavelengths and good receive power.
 
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To use old standard DF methods, you would need to have two RX units at a known distance apart in order to triangulate Triangulation - Wikipedia, the free encyclopedia U have seen switcheed phase arrays antenna setups, but this is real complicated. Using dual RX would only give direction and not distance unless you planned on using a pulsed transmitt and measured time delay between the two RX units. Why go through all the mess when you can just use GPS technology?
 
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To use old standard DF methods, you would need to have two RX units at a known distance apart in order to triangulate Triangulation - Wikipedia, the free encyclopedia U have seen switcheed phase arrays antenna setups, but this is real complicated. Using dual RX would only give direction and not distance unless you planned on using a pulsed transmitt and measured time delay between the two RX units. Why go through all the mess when you can just use GPS technology?

Becoz gps doesnt operate indoors!
 
Becoz gps doesnt operate indoors!
Indoors? Well, why was I not sent a memo on this spec requirement? :)
You have not really explained what your trying to do. Unless it is your top secret project, a little info would help.
 
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My guess is he wants to track articles or people by tagging them with a beacon. Or do the reverse and make a machine that can navigate itself through buildings GPS can't penetrate.

In any case, by multilaterating, you time the interval it takes for a signal to go from a transmitter to a receiver. It's a Time Difference of Arrival (TDOA) method, and as long as you have 4 signals to time, you can calculate those 4 distances and locate the object on a 3D map. Four receivers and 1 transmitter, or vice versa.

...So as you'd imagine, multilateration shifts all the design complexity from angle measurement to time measurement. Since radio only takes around 3ns to travel 1 meter, the transmitter and receivers have to be calibrated and synchronized with nanosecond accuracy. As for devices that already use this: there are a few. One uses a wideband RF pulse for timing. Seoul National University has been using something called a Pseudolite system to get centimeter accuracy. WiFi is about to incorporate a function to locate WiFi equipment based on signal strength, but to much less accuracy.
 
My guess is he wants to track articles or people by tagging them with a beacon. Or do the reverse and make a machine that can navigate itself through buildings GPS can't penetrate.

In any case, by multilaterating, you time the interval it takes for a signal to go from a transmitter to a receiver. It's a Time Difference of Arrival (TDOA) method, and as long as you have 4 signals to time, you can calculate those 4 distances and locate the object on a 3D map. Four receivers and 1 transmitter, or vice versa.

...So as you'd imagine, multilateration shifts all the design complexity from angle measurement to time measurement. Since radio only takes around 3ns to travel 1 meter, the transmitter and receivers have to be calibrated and synchronized with nanosecond accuracy. As for devices that already use this: there are a few. One uses a wideband RF pulse for timing. Seoul National University has been using something called a Pseudolite system to get centimeter accuracy. WiFi is about to incorporate a function to locate WiFi equipment based on signal strength, but to much less accuracy.

Thats correct. In fact that was my senior design project back at Purdue. although I did not use time domain reflectometry. I used intersecting sectors and measurements from different positions to close off an area that yields the propable location of the Tx/beacon. You can use the relative signal strength to pinpoint an objects location. a high directional antenna would suffice.
 
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