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DIY Radar.. tip?

Discussion in 'Electronic Design' started by [email protected], Oct 10, 2004.

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  1. Guest

    Any good links or tip on diy radar construction?

    I'm mostly looking into measuring oil level in a tank of glasfiber. By
    attaching such unit on the top.
     
  2. On 10 Oct 2004 15:59:44 GMT, the renowned
    Why don't you just buy a proper approved instrument from a competent
    manufacturer such as Rosemount (shop around)? You're only looking at
    maybe EUR1000, depending on manufacturer and accuracy.

    Typically this stuff operates at around 10GHz and has a whack of EMC
    and safety agency approvals.


    Best regards,
    Spehro Pefhany
     
  3. James Meyer

    James Meyer Guest

    If I had those requirements, I would go down to my local Home Depot or
    builder's supply and buy a sonic tapemeasure. They're cheap and reliable.

    Jim
     
  4. Fred Bloggs

    Fred Bloggs Guest

    Forget it. Put a run-time meter on your oil pump control.
     
  5. Dev Cloete

    Dev Cloete Guest

    Try using a ultrasonic sender and receiver (+/-48Khz) mounted on a veroboard
    and aim it at the oil surface). When you apply a signal to the sender and
    measure the return signal fom the oil level on a Oscilloscope you will find
    the phase between Tx & Rx signal varies with the oil level variation. Using
    a phase comparator & logic circuit with it, you can measure the level very
    accurately (Especialy in a tank which are stationary) Waves on the surface
    will screw the signal around too much for accurate measurement.
    Dev
     
  6. YD

    YD Guest

    On 10 Oct 2004 15:59:44 GMT,
    Off the top of my pointy head: Endress+Hauser, Foxboro, Yokogawa.
    Though in this case I'd rather go with ultrasonic rather than
    microwave.

    - YD.
     
  7. Dbowey

    Dbowey Guest

    YD posted:

    << On 10 Oct 2004 15:59:44 GMT,
    Off the top of my pointy head: Endress+Hauser, Foxboro, Yokogawa.
    Though in this case I'd rather go with ultrasonic rather than
    microwave.
    I agree. And I believe others have implied the same. The problem with MW in
    this application, is it's fast propagation time. As I recall, a "radar mile"
    is about 12.4us; the time it takes for the pulse to travel out one mile and be
    returned.

    How tall is your tank, and what is the highest and lowest content height?
    Within that range of feet, do you believe you can send the signal, receive the
    "echo" and process to an accurate result? Not very easily, but you are the one
    who must decide that. If you try it, I suggest you try a Continuous Wave
    method with a good directional coupler, at somewhere higher than 10 GHz.

    On the other-hand, ten years (or so...) ago, I read specs on IC's that are a
    complete ultrasonic transceiver that should be very easy to use in your
    application. I believe they were used in camera auto-focus devices and it was
    very simple to correlate time and distance accurately. I bet current, similar,
    ICs are even better.

    Don
     
  8. Good commercial rader level sensors (used in petrochemical tanks, for
    one big application) are in the 1-5mm accuracy/resolution range. And
    they don't depend on the varying speed of sound in layered vapor-laden
    air, at various temperatures, and perhaps with a temperature gradient.
    They can also go through a fiberglass lid - no exposure of the sensor
    is required.


    Best regards,
    Spehro Pefhany
     
  9. Spehro Pefhany wrote...
    Examples, links? :>)
     
  10. Dbowey

    Dbowey Guest

  11. Accuracy required? User interface requirements? Other environmental
    considerations?

    Without further information, I'd recommend the simplest and cheapest
    level sensing system. A dipstick.
     
  12. Dbowey

    Dbowey Guest

    But now try to build one. This *was* a request for a DIY project.

    Don
     
  13. Ok, here's a 10.525GHz (X-band) Gunn diode transceiver with 50MHz of
    varactor tuning.

    http://www.shfmicro.com/10ghz.pdf

    Anyone want to take this further?


    Best regards,
    Spehro Pefhany
     
  14. John Miles

    John Miles Guest

    They can be tuned a lot farther than +/- 50 MHz if you can swing the
    varactor across its full 0-20V (or so) range.

    I've often wondered about the kind of resolution you could get from a
    chirp radar made with those puppies. I still have a couple of 100 mW
    parts around here, so maybe one of these days....

    -- jm
     

  15. Just the proper equipment to test it is a bit on the pricey side:

    http://www.metrictest.com/product_info.jsp?mfgmdl=ADV R3182-20-27-29(D)

    Probably John Larkin has a few of these laying around..

    These things interact with some of the nastiest non-medical
    regulations in virtually every country- they are intentional radiators
    and they have intrinsic safety as well as health and safety issues. In
    the country the OP seems to be posting from (Sweden) the manual of one
    24GHz model says that they are illegal unless installed in a metal
    tank. Still, they look like they'd be a ton of fun to fool around
    with.


    Best regards,
    Spehro Pefhany
     
  16. Guest

    Any ideas what these costs roughly?
    Or what an app with the chip mentioned later in this thread would end up? :)

    The tank is approx 1.5 diameter circular. And maybe some meters length. But
    the important is the 1.5 length as the rest is simple trigonometry. The outdoor
    temperatures here are usually -10 to 30 celsius. And -25 to 40 on the extreme.
    "medium" humidity. The tank is approx .5 meters underground. So that stabelizes
    conditions further. I wonder wheather penetration of glassfibre will succed
    with precision not affected to much. Centimeter precision is enough.
    As for EM interference, I don't think that's an issue because it will likely
    need way less power than a 802.11b wlan device and be underground in soil that
    is full with water.

    I've thought a simple way to do it would be to cause some slight RFI noise by
    a high dI/dt generation through a squarewave pulse possible reduced through a
    capacitor or coil. And then have a capacitor wich is charged between the
    positive flank of transmission. And the change of input. The charge should
    be in relation to the timedelay (distance). And measured through voltage over
    it with a ADC.

    -----\ (mindstorm schematic :)
    |
    Pulse--Mosfet
    | /
    Resistor /
    |___________ RF-out
    |
    Capacitor \
    | \
    ------/

    And then something to receive it.

    | /
    | /
    Mosfet------ RF-in
    | \
    | \

    Haven't figured howto put them together really yet ;)

    Any logic chips would be way to slow, althought I know scsi-sync and
    scsi-ultra160 uses the cable as a fifo :), so maybe it's feasable (5 ns/m).
     
  17. Andrey

    Andrey Guest

    To do FMCV out of it, Varactor should be povered up with rump voltage - this
    is simple.

    Then you need mixer which makes "F transmitted minus F reflected". The
    difference frequency is function of distance. You will also need some kind
    of blanking circuit for detector to cut away moments when rump swings back

    The faster you can re-tune the gunn, the shorter distance you can measure

    Andrey



    http://www.speff.com
     
  18. Rich Grise

    Rich Grise Guest

    ....
    Take two pieces of copper pipe, one that fits inside the other with some
    gap, like a coax cable, but with a thick center conductor. Minimize the
    gap, since it's going to be a capacitor. Mount it vertically in the tank,
    and just monitor the capacitance. You'll have to calibrate it, of course.
    (your stuff has a different dielectric constant than air, probably.)

    Good Luck!
    Rich
     
  19. I once saw a contruction where they had a steel rope and they used this
    as waveguide for a somewhat lower frequency. Where this rope/wire was
    immersed, it had different properties.

    Rene
     
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