Determination of location & distance from transmitter 1

[Hookway9]

Hello

Is it possible to determine the distance to a transmitter, from receiver by analysing the wavelength of the signal received?

For example, this process used to determine the location of an airplane. However, is it possible to use the same principles to determine distance or location in a smaller range, say within a metre?

Are there any standard components or common applications that allow for this?

FYI, The application is for a animal/laboratory experiment to track the location of animals.

Thank you in advance for any help

 

[MacGyverS2000]

If you think wavelength of a signal is determined by distance to the receiver, you're in for a long haul...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[KENAT]

http://en.wikipedia.org/wiki/Radiodetermination

or more specifically the links there would perhaps be a starter for ten in ways radio waves can be used to measure this type of thing.

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[Hookway9]

No, of course not. I am not suggesting the wavelenght is determined by the distance, I wish to do the opposite, to determine the distance, given that I know the wavelenght,

 

[GregLocock]

Check out differential GPS for an off the shelf solution.





Cheers

Greg Locock


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[IRstuff]

Wavelength has nothing to do with measured distance. Wavelength MIGHT tell you something about velocity, but only if you know what the transmitted wavelength is.

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[Hookway9]

< Check out differential GPS for an off the shelf solution. >

Thank you for this suggestion, though I am looking for something very short range, within a a few metres of the receiver and very very accurate positioning (within a few mm)

 

[Hookway9]

<Wavelength has nothing to do with measured distance. Wavelength MIGHT tell you something about velocity, but only if you know what the transmitted wavelength is.>

If the amplitude could be measured and the wavelenght is known then * in theory * it ought to be possible to measure how many wavelengths (and parts thereof) the distance is.

 

[GregLocock]

"If the amplitude could be measured and the wavelenght is known then * in theory * it ought to be possible to measure how many wavelengths (and parts thereof) the distance is."

Well, then I'm afraid you'll have to find this theory and show it to us. If I have a radio wave with strength 2V/m and wavelength 300mm how do I determine how far the transmitter is from me?



Cheers

Greg Locock


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[GregLocock]

You might be trying to use the inverse square law on amplitude. It won't work on any useful scale in any useful environment on Earth. You might be able to use it in space, but it would be very rough.

Cheers

Greg Locock


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[Hookway9]

<<"If the amplitude could be measured and the wavelenght is known then * in theory * it ought to be possible to measure how many wavelengths (and parts thereof) the distance is."

Well, then I'm afraid you'll have to find this theory and show it to us. If I have a radio wave with strength 2V/m and wavelength 300mm how do I determine how far the transmitter is from me? >>

How with triangulation using many receivers? And (if necessary) using dual frequencies to produce constructive / destructive wave patterns to provide further information.

 

[Hookway9]

< you'll have to find this theory and show it to us. If I have a radio wave with strength 2V/m and wavelength 300mm how do I determine how far the transmitter is from me? >


1. Take the case where the 300mm wave starts at peak amplitude, and arrives at the receiver 180 degrees out of phase. There are a range of possible distances, 150mm, 450mm, 750,mm …. Amounting to radiating concentric circles in 2 dimensions.

2. Triangulation ought to be able to be possible to determine the qualifying distance given that the approximate distance is known from the outset.

As far as I can tell, this rests only on the assumption that the waves amplitude or position is measureable via its signal strength using standard componentry.

 

[VEBill]

"...arrives at the receiver 180 degrees out of phase..."

How do you know the relative phase? Think about it very carefully. You'll soon realize you're in a logical circle.

"...very very accurate positioning (within a few mm)..."

The larger picture is that someone needs to invent the technology you're asking for; probably not you unless you have a huge amount of time. It'll be optical to be mm-accurate.

What kind of animals need to be tracked to with a few mm? Elephants? Insects?

Is this for school?

 

[KENAT]

Triangulation may be a much better idea. Transponders or some such on the sample population and (assuming a flat field of play) 2 receivers you should be able to obtain location.

At a previous job we tested something like this on a very large scale (though the transponder was about the size of a thumb/flash drive) and it worked very well.

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[IRstuff]

1. Just consider the case where you are 10 wavelengths away; you still see the same frequency, but lower amplitude; this is classic range ambiguity in interferometry. I think you are confusing interferometry with general range measurements. Interferometry only deals with distance measurement over a single wavelength, by using phase comparison; beyond that first wavelength, you must use either another wavelength or another means to deal with range ambiguity. In your example, a 300 mm wavelength could probably be accurately measured to 3mm, but you can achieve better than that with a conventional laser range finder.

2. Triangulation uses ASA to determine range, without using wavelength whatsoever.

TTFN
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[MacGyverS2000]

The OP is obviously not versed enough in electrical/signal matters (basic physics?) to make such a project work, so we're throwing random ideas at a moving dartboard. Without a clear idea of what he's after, there's no hope of providing a useful solution...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Hookway9]

< At a previous job we tested something like this on a very large scale (though the transponder was about the size of a thumb/flash drive) and it worked very well. >

Can I ask, what was the means for determination of distance from transponders, was it Radiolocation involving RSSI, TOA and AOA?

A pet microchip is very small. Conceivably, could the transponders be smaller than a USB drive?

 

[Hookway9]

< 2. Triangulation uses ASA to determine range, without using wavelength whatsoever. >

Surely, Triangulation need not be limited to ASA? Putting aside Wavelenght, what is the most expedient way of finding distance?

 

[VEBill]

Time of flight (timing). But mm accuracy implies a very (very) high clock speed.

Some of us may be concerned that your requirements push the limits of the state of the art, but your questions are relatively basic.

 

[IRstuff]

"Surely, Triangulation need not be limited to ASA? Putting aside Wavelenght, what is the most expedient way of finding distance?"

ASA; which is how the great Everest, etal, systematically performed the Great Survey of India, which was before anyone had even radios. Of course, the ultimate cost of the survey nearly bankrupted the British East Indies company.

Of course, for the short distance the OP seems to be implying, there's this:

https://www.mysick.com/partnerPortal/ProductCatalog/DataSheet.aspx?ProductID=40711

I've never been clear how Sick does it; I presume it's doing an FMCW approach.

TTFN
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