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Determination of location & distance from transmitter

Determination of location & distance from transmitter

Determination of location & distance from transmitter

(OP)
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

RE: Determination of location & distance from transmitter

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

RE: Determination of location & distance from transmitter

(OP)
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,

RE: Determination of location & distance from transmitter

(OP)
< 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)

RE: Determination of location & distance from transmitter

(OP)
<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.

RE: Determination of location & distance from transmitter

"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


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Determination of location & distance from transmitter

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


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Determination of location & distance from transmitter

(OP)
<<"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.

RE: Determination of location & distance from transmitter

(OP)

< 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.

RE: Determination of location & distance from transmitter

"...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?

RE: Determination of location & distance from transmitter

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.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: Determination of location & distance from transmitter


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
FAQ731-376: Eng-Tips.com Forum Policies

Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers

RE: Determination of location & distance from transmitter

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

RE: Determination of location & distance from transmitter

(OP)
< 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?

RE: Determination of location & distance from transmitter

(OP)
< 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?

RE: Determination of location & distance from transmitter

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.

RE: Determination of location & distance from transmitter

"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/ProductCatalo...

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

TTFN
FAQ731-376: Eng-Tips.com Forum Policies

Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers

RE: Determination of location & distance from transmitter

OP- there are numerous ways of estimating the position of a location use radio transmitters and receivers, so if you write a spec we can probably rule some out, and suggest others.

As a general point, an accuracy/repeatability of 1mm in 2d or 3d over the length of 5m is not possible with non contacting methods with finite budgets. To get that we use Faro Arms, which would be no good for dynamic measurements.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Determination of location & distance from transmitter

A group of technologies using UWB (ultra wideband signals) called Micropower Impulse Radar (MIR) have been used for this kind of position sensing. Basically impulse RF transmitter and equivalent-time sampling receivers to create a time-of-flight position sensing system. But this is a group of technologies, patents, methodologies, demo circuits, and not final products licensed out of Lawerence Livermore National Labs 15 to 20 years ago.

RE: Determination of location & distance from transmitter

(OP)
<https://www.mysick.com/partnerPortal/ProductCatalo...

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

Thank you for this lead, FMCW appears to be very relevant.>

RE: Determination of location & distance from transmitter

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

No intention of pushing the state of the art, only to define the limits of standard process.

< write a spec>

Yes. I will, though for now:
Range: 800mm
Accuracy: 1mm
2 dimensions.

Many thanks to all for the detailed leads and help

RE: Determination of location & distance from transmitter

Do you have clear overhead view of the animal enclosure? Why not optical tracking via one or more video cameras?

RE: Determination of location & distance from transmitter

(OP)
<Do you have clear overhead view of the animal enclosure? Why not optical tracking via one or more video cameras?>

Yes, a very simple practical approach - thank you!

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