Can pay real money for the answer. Is there a device or technology to measure the distance between two nodes?
I am thinking of a radio emitter and a material to reflect it. And calculate the time it bounces back and find the distance. Or calculate the amount of decrease of the power of the signal.
I can pay about 100-500$ for a good answer.
Answer:
Need more information. How far apart are these nodes? What kind of accuracy do you need?
For distances up to about 3 meters, you can buy an electronic inside micrometer.
For distances of a few kilometers, there are various laser-ranging schemes (check out the "Green Bank Telescope").
Beyond a few kilometers, people usually use GPS, or differential GPS.
I don't know how big these remote nodes of yours are, but a very accurate range-finding device involves pulse-firing a laser (which could easily be done 50 times a second) and measuring the time it takes for each pulse to return after being reflected off a mirror surface mounted on the target.
The trick is to use a retroreflector:
http://en.wikipedia.org/wiki/retroreflec...
so that the light always comes back in the same direction, regardless of the angle at which you hit the reflector.
i need you to be alil more specific plz
a PM is fineif you will send me more info..
are you talking networking, gps, wifi, blue tooth, wired networking, avionics, outerspace?
you can buy a 102 0-Inch to 1-Inch .001-Inch Graduation Micrometer from amazon...i have no idea what that is but i need the money :D
bounce laser off a mirror at distant point, measure how long takes to return
need a very fast clock for this
http://en.wikipedia.org/wiki/laser_range...
and you haven't really specified enough info to provide an good answer
what is the approx distance between nodes
what the required accuracy of measurement
You are going to be hard pressed to get that kind of accuracy. First of all, optics are out if the space that the two devices occupy is not open. Your next choice will be RF.
Will these devices be stationary or moving? Are you only interested in distance or is direction (az & el) important.
If distance and/or speed is what you are looking for, you could have the node transmit a pulse and use doppler shift to find distance and speed.
If you need direction also you could use the above for range, and use a mode former and some processing to find the 3-d direction the signal is coming from. If you used a high enough frequency and some substrate material with a high permittivity, this device could actually be kept relatively small.\
Hope that has given you stuff to search on.
What are you trying to do with this?
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