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Parking Sensors

Discussion in 'Electronic Basics' started by Michael, Dec 24, 2007.

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  1. Michael

    Michael Guest

    Hi,

    I'm looking at parking sensors and can't work out why there aren't lists of
    sites on Google telling you how to make homemade versions. Surely all you
    need is an array of ultrasonic sensors each one "pinged" in turn to avoid
    interference and then read the distance values into a uC for
    analysis........or am I missing something?

    Cheers,

    Michael
     
  2. Sjouke Burry

    Sjouke Burry Guest

    Just some months ago I took one apart.
    One exponential horn(~1 inch cross)as transmitter, and
    another such horn as receiver.
    I think you can buy tweeters looking like that.
    Opening angle about 120(+/-60)degrees opening angle.
    Copper/ceramic disks such as in most beepers as transmitter
    and receiver.

    the following method was used in a kodak automatic focus camera
    in the dark ages(~1975??) and obviously broke down when
    photographing through a windowpane :) .
    Usable range was about 10m (11-12yards).

    Transmit ~ 2-6 bursts per second, 1 msec long, ~20-50 KHZ.
    1 msec is about 150mm(150 out,150 back,300mm/msec sound speed).
    I would advice to use 3 analog multipliers to multiply
    the incoming signal with the 4'thpower of time, or in other words,
    use a sawtooth signal to start with, feed that to both inputs
    of the first multiplier,output to the second multiplier, then feed
    receiver and 4'th power sawtooth to the third multiplier.
    That way your return signal strength on the timescale will be nearly
    constant, only the noise will rise with increasing distance,
    until the signal becomes useless.
    Then trigger on that, and measure time to get distance.
    Also the amplitude of your sawtooth at the trigger moment, stands
    for time/distance measured.
     
  3. default

    default Guest

    Lots of information on robotics hobby sites

    http://www.sparkfun.com/commerce/product_info.php?products_id=8502#
    Ultrasonic Range Finder - Maxbotix LV-EZ0

    SKU#: SEN-08502

    Price: $24.95
    Description: This is the fantastically easy to use sensor from
    Maxbotix. We are extremely pleased with the size, quality, and ease of
    use of this little range finder. The serial interface is a bit odd
    (it's RS232 instead of standard TTL), but the PWM and Analog
    interfaces will allow any micro to listen easily enough. The sensor
    provides very accurate readings of 0 to 255 inches (0 to 6.45m) in 1
    inch increments with little or no dead zone!
    --
     
  4. default

    default Guest

    A Cheap Ultrasonic Range Finder
    http://www.micro-examples.com/public/microex-navig/doc/090-ultrasonic-ranger.html


    Distance Sensing

    devices for wireless distance and position determination useful as
    gesture controllers for robotic musical instruments

    http://www.logosfoundation.org/ii/distance_sensing.html
    --
     
  5. default

    default Guest

    TL852
    SONAR RANGING RECEIVER IC
    http://www.ortodoxism.ro/datasheets/texasinstruments/tl852.pdf

    Cheap Sonar circuit schematic
    http://www.seattlerobotics.org/encoder/apr97/sonar.html


    Whole PARKING SONAR schematic with no special parts or programming
    http://www.geocities.com/CapeCanaveral/Launchpad/3632/sonar_sc.gif
    and write up
    http://www.geocities.com/CapeCanaveral/Launchpad/3632/sonar.htm
    --
     
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