Distance Measurement using RF

Discussion in 'The Projects Forum' started by alosurve, Jul 20, 2010.

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  1. alosurve

    Thread Starter New Member

    Apr 24, 2010
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    hello every1,i want to know whether it is possible to measure distance using rf..my idea is to make use of rf waves and based on time of flight,distance calculation may be achieved..i doubt its accuracy and what are the possible concerns that need to be visualized..if any1 has worked on this before could pls help me..suggestions regarding other techniques of distance measurement will be of great help..
    Details: 1. my distance measurement will not be taking place in an open environment..so obstacles must be considered..i guess..!!
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Radar is the means of doing such since the 1930's. It works by measuring time of flight. If you are working in a closed environment, then this link may be of interest - http://en.wikipedia.org/wiki/Ultra-wideband Keeping power levels very low should be of interest.

    There are also laser-based means of distance measurement. It would be very helpful if we had some idea of the application.
     
  3. tubelite

    New Member

    Jul 20, 2010
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    I think its completely possible (correct me if i'm wrong anyone else) but aren't police radar guns made around this concept but get velocity info which can easily be used to find distance info. Even those things you get from home depot (laser guns) measure distance and temperature (from a distance) will do this. This is probably a more line of sight (LOS) option you could build for and requires no communication back from the object you are tracking.

    You could also do something that has communications from the device back to the tracker and use signal strength to sort of figure out its location (radial location)... there's a lot of things you could do but depends on what your looking for as far as complexity and resolution.

    I'm sure the more experienced forum members can answer this question... making my reply... utterly useless... *shakes head at himself and looks down* I'm sorry, i'm a lil weird.
     
  4. alosurve

    Thread Starter New Member

    Apr 24, 2010
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    i'm actually thinking of using an a yagi uda beam array to track rfid tags that will be placed on animals..as in the way they show on national geographic..the tracking of herds..so one parameter that is essential for this as a result is the distance at which the tag is positioned..!! how do i determine the distance in such a case?
    +
     
  5. alosurve

    Thread Starter New Member

    Apr 24, 2010
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    hey tubelite..like ur login name..pour in whatever u have and that ll be surely of some help to me..!! thanx buddy.
     
  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    You apparently are talking about a transponder-type of system, not simply passive reflection. Look up aviation Distance Measuring Equipment (DME), which is an older technology for the same thing.

    John
     
  7. studiot

    AAC Fanatic!

    Nov 9, 2007
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    It really doesn't matter what location system you use, you have to have a number of accurately positioned base stations.Nowadays these are usually satellites.

    Older terrestrial methods that might help are

    Tellurometer
    Loran
    Decca Navigator
    Trisponder
    Syledis
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    RADAR (Radio Detection And Ranging) has been around since WWII days.

    It's really a bit beyond the scope of these forums, which are oriented towards beginners.

    However, it takes roughly 6.28uS (microseconds) for RF energy to travel 1 nautical mile. So, if a burst of RF energy travels for 1 mile and then is reflected by an object at that range, the round trip will take roughly 12.54uS. At these high speeds, it's difficult for hobbyists to achieve any kind of resolution accuracy using available components that aren't priced exorbitantly.

    There is also the matter of safety. In order to get a usable return signal from small objects, it requires quite a bit of RF energy. If people are exposed to high-power RF in the high frequency ranges, harm occurs very quickly.

    If you would like to learn more about RADAR, go here:
    http://www.phy.davidson.edu/instrumentation/NEETS.htm
    Read Module 18.

    Sonar and PIR are more hobbyiest-friendly.
     
  9. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    Ditto on the RF energy problem. A RADAR that is capable of detecting an aircraft at 200miles will be outputing somewhere like a 2MW pulse. A 900W microwave (similar frequency) is encased inside a protective shield.

    Now that I have cooked your chicken have you considered ultrasonics. If you can design a "set" of transducers mounted in a fan arrangement you could detect the distance of any and all object within its arc. If you cycle through the transducers (maybe 6) quickly one at a time repeatedly you could almost build a picture of the room. You could even include tilt and position sensors to create a 3D image.

    Just a bit of a mind bender. Remember.... if you can think it... it can can most likely be built (does not include Star Trek ideas):D
     
  10. studiot

    AAC Fanatic!

    Nov 9, 2007
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    The systems I mentioned don't use anything like this power and are capable of being used over thousands of miles.
    The Tellurometer, for instance, was the instrument of choice in the main geodetic survey of Australia. It operates from a 12 volt car battery.
     
  11. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    According to Wikipedia, the tellurometer only weighted 38# ;)

    [​IMG]

    I think a simple ping device (as used in DME) would be more applicable to animal tracking. Admittedly, the concept of tellurometry and DME are very similar.

    John
     
  12. studiot

    AAC Fanatic!

    Nov 9, 2007
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    We haven't been told if the tracking is for animals (or birds) travelling intercontinental distances, or just to monitor the local tom cat's nocturnal excursions.

    Whilst I have used a Tellurometer, it was not in OZ.
     
  13. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    What frequency does a Tellurometer work on? Is it a transmitter as well?
     
  14. beenthere

    Retired Moderator

    Apr 20, 2004
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    To pull this back on topic, the OP might think about tracking collars and two stations with yagi antennas to give distance through simple trig. GPS can give relative positions of the stations with a very small error, so the tracking stations can be mobile.

    To windoze killa: Google turns up 58,000 hits on " Tellurometer"
     
    Last edited: Jul 20, 2010
  15. indiansiva555@gmail.com

    New Member

    Jul 24, 2011
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    Please post complete technical information about measuring distance using RF. Your overview is not going to make any idea.....
     
  16. Wendy

    Moderator

    Mar 24, 2008
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    Please look at the age and dates before replying to threads, beenthere died recently, and the OP is long gone.
     
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