Connect with us

Micro transmitters/receivers for finding objects?

Discussion in 'Electronic Basics' started by Michael, Oct 16, 2003.

Scroll to continue with content
  1. Michael

    Michael Guest

    Hello,
    I was wondering if you could help me. I would like to do the
    following:
    Put a small transmitter onto a product for this example lets say a
    model hobby rocket that will be launched using a standard hobby rocket
    engine you can buy in any store. They usually don't go more than
    100-200 yards or so but I would need the device to be able to locate
    it in dense tree cover (woods) without being able to see exactly where
    it went.
    Is there a receiver that can direct me exactly to the spot where the
    rocket is? (containing the beeping transmitter).
    Of course there are some constraints:
    - the size of the transmitter has be very small (approx 4mm wide or
    less, it can be several mm's longer in length). Also the battery has
    to be this small as well, possible cylindrical in shape.
    - the receiver that will direct me to the transmitter also has to be a
    relatively small device (like the size of a walkie talkie, if
    possible)
    - each of these units should be somewhat inexpensive to produce (under
    $20?)
    - no FCC or other federal licenses required
    - relatively easy to learn and accurate if within the 100-200 yard
    range

    Is this possible? Does anyone know where I can find these components
    or companies that can produce them?
    If not, are their plans that are available where we can build our own
    receiver?

    If you have any questions, please contact me.

    Michael
     
  2. No single receiver, following a simple telemetry signal such as
    you describe, can do this without some effort. Said effort takes the
    form of triangulation.

    Using a directional antenna and compass, you would take a bearing
    on the signal from your launch point, and mark it on a map. You would
    then walk or drive a couple of miles in a direction approximately 90
    degrees to your first bearing and take another one. Repeat this process
    once more, and you will have three lines on your map. Where they all
    cross is approximately where the transmitter will be.

    If you wanted to get really crazy, you could rig some sort of
    miniature GPS receiver in the rocket, and have it send its raw serial
    data via another transmitter. This, however, gets into some weight and
    cost factors that I'm sure would exceed yours.
    The receiver is less of an issue than the antenna. The antennas
    used in DF work are, by design, considerably larger than the radio.

    You may want to get in touch with whatever ham radio club is local
    to your area (listings may be found at www.arrl.org), and ask about
    transmitter hunting. You may even want to get your ham license along the
    way.

    Good luck.
     
  3. Michael

    Michael Guest

    Thank you very much for your response. I was doing all kinds of
    research but no one seemed to even have a clue as to what I was
    looking for. I will see how it goes at the ham radio club.

    Thanks again.
     
  4. Charlie+

    Charlie+ Guest

    On 15 Oct 2003 20:49:26 -0700, (Michael) wrote
    as underneath my scribble :

    I have seen for sale (for under £10 ) a small transmitter in a single
    2 wire chip, as far as I recall it transmits at 400+ MHz FM ,3-12 v
    and looks like a small tantalum capacitor, all it needs is a battery,
    and seems inexpensive. Try Maplin etc search for GT39N, the receiver
    is another matter, there was a receiver which was the more expensive
    part however the direction finding ?? if it were my problem I would
    probably start trial with the Tx chip and a handheld scanner type Rx
    and a small yagi type directional array ariel which you can make
    yourself or adapt a TV yagi array. The scanner would have to have a
    signal strength meter and prefrably a BFO as well, or you could add
    modulation to the Tx supply and get an audible signal that way! Range
    - battery longevity etc, no idea youd have to experiment. You could
    also add a small piezzo buzzer to your rocket to get you the final
    location within earshot.
    Charlie+
    snip
     
  5. [snip]
    The ferrite loopstick inside(!) the common AM pocket radio can be used
    to get a null of an AM transmitter, and by using triangulation as you
    stated, can give the location of the Tx. This antenna is not
    "considerably larger" than the radio. I don't know if this could be
    applied to VHF stations, but if so, it would work similarly.

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  6. These kinds of transmitters are used by the organizations working with
    endangered species of animals. Some are small and light enough to be
    strapped onto birds. The receiver is a special one with a directional
    Yagi antenna that's a few feet long. The receiver gives the signal
    strength, and the hand-held antenna is pointed in the direction of
    maximum signal. There is no apparent need to do triangulation, just
    approach the transmitter in the direction that the antenna is pointing
    and as the signal gets stronger, you're heading right for it. If it
    gets weaker, then you're going in the wrong direction.
    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-