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metal dector for barbed wire fences

Discussion in 'Embedded' started by Hul Tytus, Jun 16, 2012.

  1. Hul Tytus

    Hul Tytus Guest

    comp.arch.embedded,sci.electronics.components
    metal dector for barbed wire fences

    Anybody here have any suggestions for possible ways to detect fence wire,
    mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square matrix?
    Typical mounting would be on a tractor or trailer, so the detector would need
    a sense of direction, ie looking outward not inward. Minimum range would be
    around one foot with 4 feet probably optimum.
    Typical retail metal detectors have a short range and need a metal free
    environment, leaving the methods they use somewhat doubtful. Evidently, there
    are detectors with seperate heads/coils and 1-5 foot ranges but, once again,
    require a metal free environment.
    One possible area would utilize rf antenna's, one transmiting and the other
    recieving a reflection from the wire(s). A parabolic or corner reflector type
    antenna maybe if not for the high frequency - two 12 inch antenna's would be
    about max size and that's in the gigaherts range, which might be a problem.
    Any suggestions along this line will be appreciated.

    Hul
     
    Hul Tytus, Jun 16, 2012
    #1
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  2. Hul Tytus

    Tim Wescott Guest

    On Sat, 16 Jun 2012 15:04:18 +0000, Hul Tytus wrote:

    > comp.arch.embedded,sci.electronics.components metal dector for barbed
    > wire fences
    >
    > Anybody here have any suggestions for possible ways to detect fence
    > wire,
    > mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square
    > matrix? Typical mounting would be on a tractor or trailer, so the
    > detector would need a sense of direction, ie looking outward not inward.
    > Minimum range would be around one foot with 4 feet probably optimum.
    > Typical retail metal detectors have a short range and need a metal
    > free
    > environment, leaving the methods they use somewhat doubtful. Evidently,
    > there are detectors with seperate heads/coils and 1-5 foot ranges but,
    > once again, require a metal free environment.
    > One possible area would utilize rf antenna's, one transmiting and the
    > other
    > recieving a reflection from the wire(s). A parabolic or corner reflector
    > type antenna maybe if not for the high frequency - two 12 inch antenna's
    > would be about max size and that's in the gigaherts range, which might
    > be a problem.
    > Any suggestions along this line will be appreciated.
    >
    > Hul


    What are you actually trying to do? Is this an operator aid, to keep
    from driving into the fence, or for a robotic tractor, or what?

    You may be able to make a metal detector directional simply by backing up
    the detection coil with a metal plate, one or two feet back. Metal
    detectors work with near-field radiation of a low frequency signal (in
    the 100's of kHz, if I recall correctly), and look for changes in the
    coil inductance caused by nearby metal. Placing the coil a foot or two
    from the metal backing will leave the detector "detecting" the backing --
    but it'll be constant; as long as there's enough change from the metal
    you want to detect, things should work.
     
    Tim Wescott, Jun 16, 2012
    #2
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  3. Hul Tytus

    Paul Guest

    In article <jri79h$opj$>, says...
    >
    > comp.arch.embedded,sci.electronics.components
    > metal dector for barbed wire fences
    >
    > Anybody here have any suggestions for possible ways to detect fence wire,
    > mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square matrix?
    > Typical mounting would be on a tractor or trailer, so the detector would need
    > a sense of direction, ie looking outward not inward. Minimum range would be
    > around one foot with 4 feet probably optimum.
    > Typical retail metal detectors have a short range and need a metal free
    > environment, leaving the methods they use somewhat doubtful. Evidently, there
    > are detectors with seperate heads/coils and 1-5 foot ranges but, once again,
    > require a metal free environment.
    > One possible area would utilize rf antenna's, one transmiting and the other
    > recieving a reflection from the wire(s). A parabolic or corner reflector type
    > antenna maybe if not for the high frequency - two 12 inch antenna's would be
    > about max size and that's in the gigaherts range, which might be a problem.
    > Any suggestions along this line will be appreciated.
    >
    > Hul


    Alternatively use the barb wire fence as an antenna for LF low power
    signal and get the strength detection of carrier to denote when too
    close.



    --
    Paul Carpenter |
    <http://www.pcserviceselectronics.co.uk/> PC Services
    <http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
    <http://www.gnuh8.org.uk/> GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
    <http://www.badweb.org.uk/> For those web sites you hate
     
    Paul, Jun 16, 2012
    #3
  4. Hul Tytus

    Jamie Guest

    Hul Tytus wrote:

    > comp.arch.embedded,sci.electronics.components
    > metal dector for barbed wire fences
    >
    > Anybody here have any suggestions for possible ways to detect fence wire,
    > mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square matrix?
    > Typical mounting would be on a tractor or trailer, so the detector would need
    > a sense of direction, ie looking outward not inward. Minimum range would be
    > around one foot with 4 feet probably optimum.
    > Typical retail metal detectors have a short range and need a metal free
    > environment, leaving the methods they use somewhat doubtful. Evidently, there
    > are detectors with seperate heads/coils and 1-5 foot ranges but, once again,
    > require a metal free environment.
    > One possible area would utilize rf antenna's, one transmiting and the other
    > recieving a reflection from the wire(s). A parabolic or corner reflector type
    > antenna maybe if not for the high frequency - two 12 inch antenna's would be
    > about max size and that's in the gigaherts range, which might be a problem.
    > Any suggestions along this line will be appreciated.
    >
    > Hul


    Ultra sonic projected on the fence wire should make it vibrated. A
    ultrasonic mic just behind the transducer should detect this.

    Fence wire is a hard surface and the only thing I can see that may
    hamper this is rust..

    If you transmit a low frequency magnetic wave in the vicinity,
    surface rust on the metal may produce some nice G/T hz signals. Of
    course, you need a detector for that. Maybe IR . who knows.. ;)

    Jamie
     
    Jamie, Jun 16, 2012
    #4
  5. Hul Tytus

    Guest

    Paul - that's definite possibility but, as you say, an alternative if
    "plan a" doesn't prove feasible.

    Hul

    In comp.arch.embedded Paul <> wrote:
    > In article <jri79h$opj$>, says...
    > >
    > > comp.arch.embedded,sci.electronics.components
    > > metal dector for barbed wire fences
    > >
    > > Anybody here have any suggestions for possible ways to detect fence wire,
    > > mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square matrix?
    > > Typical mounting would be on a tractor or trailer, so the detector would need
    > > a sense of direction, ie looking outward not inward. Minimum range would be
    > > around one foot with 4 feet probably optimum.
    > > Typical retail metal detectors have a short range and need a metal free
    > > environment, leaving the methods they use somewhat doubtful. Evidently, there
    > > are detectors with seperate heads/coils and 1-5 foot ranges but, once again,
    > > require a metal free environment.
    > > One possible area would utilize rf antenna's, one transmiting and the other
    > > recieving a reflection from the wire(s). A parabolic or corner reflector type
    > > antenna maybe if not for the high frequency - two 12 inch antenna's would be
    > > about max size and that's in the gigaherts range, which might be a problem.
    > > Any suggestions along this line will be appreciated.
    > >
    > > Hul


    > Alternatively use the barb wire fence as an antenna for LF low power
    > signal and get the strength detection of carrier to denote when too
    > close.




    > --
    > Paul Carpenter |
    > <http://www.pcserviceselectronics.co.uk/> PC Services
    > <http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
    > <http://www.gnuh8.org.uk/> GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
    > <http://www.badweb.org.uk/> For those web sites you hate
     
    , Jun 16, 2012
    #5
  6. Hul Tytus

    Bruce Varley Guest

    <> wrote in message news:jrit4k$d6c$...
    > Paul - that's definite possibility but, as you say, an alternative if
    > "plan a" doesn't prove feasible.
    >
    > Hul
    >
    > In comp.arch.embedded Paul <> wrote:
    >> In article <jri79h$opj$>, says...
    >> >
    >> > comp.arch.embedded,sci.electronics.components
    >> > metal dector for barbed wire fences
    >> >
    >> > Anybody here have any suggestions for possible ways to detect fence
    >> > wire,
    >> > mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square
    >> > matrix?
    >> > Typical mounting would be on a tractor or trailer, so the detector
    >> > would need
    >> > a sense of direction, ie looking outward not inward. Minimum range
    >> > would be
    >> > around one foot with 4 feet probably optimum.
    >> > Typical retail metal detectors have a short range and need a metal
    >> > free
    >> > environment, leaving the methods they use somewhat doubtful. Evidently,
    >> > there
    >> > are detectors with seperate heads/coils and 1-5 foot ranges but, once
    >> > again,
    >> > require a metal free environment.
    >> > One possible area would utilize rf antenna's, one transmiting and
    >> > the other
    >> > recieving a reflection from the wire(s). A parabolic or corner
    >> > reflector type
    >> > antenna maybe if not for the high frequency - two 12 inch antenna's
    >> > would be
    >> > about max size and that's in the gigaherts range, which might be a
    >> > problem.
    >> > Any suggestions along this line will be appreciated.
    >> >
    >> > Hul

    >
    >> Alternatively use the barb wire fence as an antenna for LF low power
    >> signal and get the strength detection of carrier to denote when too
    >> close.

    >

    Driving the fence with VLF, if you can do it, is likely to be the most
    robust solution. I've done a similar thing for detecting underground wiring
    where only one end is accessible, a simple loop coil detector easily
    indicates proximities in the oo-1 metre range.

    An unrelated thought, the barbed wire will make it easy to arrange a backup
    override, in case whatever it is gets too close to the fence. A vertical
    trip wire will catch on the barbs, and that can activate an energency stop.
     
    Bruce Varley, Jun 17, 2012
    #6
  7. "Hul Tytus" skrev i nyhetsmeldingen: jri79h$opj$ ...
    > Anybody here have any suggestions for possible ways to detect fence
    > wire,
    >mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square matrix?


    This application makes my head shouts "radar!".. not metal detector..
     
    Morten Leikvoll, Jun 19, 2012
    #7
  8. On Saturday, June 16, 2012 10:04:18 AM UTC-5, Hul Tytus wrote:
    > comp.arch.embedded,sci.electronics.components
    > metal dector for barbed wire fences
    >
    > Anybody here have any suggestions for possible ways to detect fence wire,
    > mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square matrix?
    > Typical mounting would be on a tractor or trailer, so the detector would need
    > a sense of direction, ie looking outward not inward. Minimum range would be
    > around one foot with 4 feet probably optimum.
    > Typical retail metal detectors have a short range and need a metal free
    > environment, leaving the methods they use somewhat doubtful. Evidently, there
    > are detectors with seperate heads/coils and 1-5 foot ranges but, once again,
    > require a metal free environment.
    > One possible area would utilize rf antenna's, one transmiting and the other
    > recieving a reflection from the wire(s). A parabolic or corner reflector type
    > antenna maybe if not for the high frequency - two 12 inch antenna's would be
    > about max size and that's in the gigaherts range, which might be a problem.
    > Any suggestions along this line will be appreciated.
    >
    > Hul




    Hmmm, wondering if a vision system could be made to do this. maybe something with a very limited depth of field on 3 cameras such that, a correction signal is generated by the outlying cameras if the image from the central camera blurs.
     
    1 Lucky Texan, Jul 11, 2012
    #8
  9. Hul Tytus

    mikelake Guest

    >On Saturday, June 16, 2012 10:04:18 AM UTC-5, Hul Tytus wrote:
    >> comp.arch.embedded,sci.electronics.components
    >> metal dector for barbed wire fences
    >>
    >> Anybody here have any suggestions for possible ways to detect fenc

    wire,
    >> mostly 1, 2 or 3 levels of barbed wire but also some 8 inch squar

    matrix?
    >> Typical mounting would be on a tractor or trailer, so the detector woul

    need
    >> a sense of direction, ie looking outward not inward. Minimum range woul

    be
    >> around one foot with 4 feet probably optimum.
    >> Typical retail metal detectors have a short range and need a meta

    free
    >> environment, leaving the methods they use somewhat doubtful. Evidently

    there
    >> are detectors with seperate heads/coils and 1-5 foot ranges but, onc

    again,
    >> require a metal free environment.
    >> One possible area would utilize rf antenna's, one transmiting and th

    other
    >> recieving a reflection from the wire(s). A parabolic or corner reflecto

    type
    >> antenna maybe if not for the high frequency - two 12 inch antenna'

    would be
    >> about max size and that's in the gigaherts range, which might be

    problem.
    >> Any suggestions along this line will be appreciated.
    >>
    >> Hul

    >
    >
    >
    >Hmmm, wondering if a vision system could be made to do this. mayb

    something with a very limited depth of field on 3 cameras such that,
    correction signal is generated by the outlying cameras if the image fro
    the central camera blurs.
    >


    I was also thinking about a vision based system - of course if the tracto
    is going through fields with crops/grass/weeds blocking the camera's vie
    of the fence, then it isn't going to be reliable in all situations.

    A camera with focus set for near objects would have a sharp view of a wir
    fence. Edge detection techniques with some simple pattern matching woul
    probably work quite well for picking the horizontal wires of the fence. I
    could be further developed to identify the actual 'barbed' pieces.

    Maybe overkill for the intended application??





    ---------------------------------------
    Posted through http://www.EmbeddedRelated.com
     
    mikelake, Jul 20, 2012
    #9
  10. Hul Tytus

    Paul Guest

    In article <>, 29427
    @embeddedrelated says...
    >
    > >On Saturday, June 16, 2012 10:04:18 AM UTC-5, Hul Tytus wrote:
    > >> comp.arch.embedded,sci.electronics.components
    > >> metal dector for barbed wire fences
    > >>
    > >> Anybody here have any suggestions for possible ways to detect fence

    > wire,
    > >> mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square

    > matrix?
    > >> Typical mounting would be on a tractor or trailer, so the detector would

    > need
    > >> a sense of direction, ie looking outward not inward. Minimum range would

    > be
    > >> around one foot with 4 feet probably optimum.
    > >> Typical retail metal detectors have a short range and need a metal

    > free
    > >> environment, leaving the methods they use somewhat doubtful. Evidently,

    > there
    > >> are detectors with seperate heads/coils and 1-5 foot ranges but, once

    > again,
    > >> require a metal free environment.
    > >> One possible area would utilize rf antenna's, one transmiting and the

    > other
    > >> recieving a reflection from the wire(s). A parabolic or corner reflector

    > type
    > >> antenna maybe if not for the high frequency - two 12 inch antenna's

    > would be
    > >> about max size and that's in the gigaherts range, which might be a

    > problem.
    > >> Any suggestions along this line will be appreciated.
    > >>
    > >> Hul

    > >
    > >Hmmm, wondering if a vision system could be made to do this. maybe

    > something with a very limited depth of field on 3 cameras such that, a
    > correction signal is generated by the outlying cameras if the image from
    > the central camera blurs.


    All vision systems used outside suffer from problem below

    > I was also thinking about a vision based system - of course if the

    tractor
    > is going through fields with crops/grass/weeds blocking the camera's view
    > of the fence, then it isn't going to be reliable in all situations.


    Worst still heading towards the sun and see next to nothing.

    > A camera with focus set for near objects would have a sharp view of a wire
    > fence. Edge detection techniques with some simple pattern matching would
    > probably work quite well for picking the horizontal wires of the fence. It
    > could be further developed to identify the actual 'barbed' pieces.


    Assumes all wire fences are nearly horizontal compared to camera
    perspective. No breaks or other things attached to barbed wire like
    signs syaing "keep out"..

    > Maybe overkill for the intended application??


    Very possibly


    --
    Paul Carpenter |
    <http://www.pcserviceselectronics.co.uk/> PC Services
    <http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
    <http://www.gnuh8.org.uk/> GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
    <http://www.badweb.org.uk/> For those web sites you hate
     
    Paul, Jul 20, 2012
    #10
  11. On 07/11/2012 07:18 AM, 1 Lucky Texan wrote:
    > On Saturday, June 16, 2012 10:04:18 AM UTC-5, Hul Tytus wrote:
    >> comp.arch.embedded,sci.electronics.components
    >> metal dector for barbed wire fences
    >>
    >> Anybody here have any suggestions for possible ways to detect fence wire,


    Search for "search coils pdf" will turn up
    a lot of documents on the topic. The one
    I keep around features many of the applicable
    patents.

    Anyway, you do have some interesting contstraints.
    I'm thinking along the lines of how you could
    excite the wire strands (exciter coil at one
    end of the tractor) and a detector coil at
    the other.

    It wasn't clear whether you are trying to prevent
    driving directly into a fence while crossing a
    planted field or if you are trying to monitor
    the fence location as in mowing close along the
    fence.


    --- Posted via news://freenews.netfront.net/ - Complaints to ---
     
    David K. Bryant, Jul 25, 2012
    #11
  12. On Jul 25, 2:01 pm, "David K. Bryant" <>
    wrote:
    > On 07/11/2012 07:18 AM, 1 Lucky Texan wrote:
    >
    > > ...snip...

    >
    > It wasn't clear whether you are trying to prevent
    > driving directly into a fence while crossing a
    > planted field or if you are trying to monitor
    > the fence location as in mowing close along the
    > fence.
    >
    > --- Posted via news://freenews.netfront.net/ - Complaints to ---



    Yes, I think there have been farming vehicles for some time now that
    use GPS to mark the area in which they operate. I don't know how
    accurate they are or if they require a large 'buffer' zone for error.
    Perhaps switching from a GPS system to a more sensitive/accurate
    system is what the OP is attempting?
     
    1 Lucky Texan, Jul 30, 2012
    #12
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