Help needed in RADAR crkt

Discussion in 'Electronics Resources' started by ts1, Feb 7, 2012.

  1. ts1

    Thread Starter New Member

    Feb 7, 2012
    1
    0
    Hello friends,

    I have a BUSHNELL radar gun here and I need to know how to get the outputs from its circuit before entering the display circuit. I mean as a voltage or bits not displayed.

    That's in order to feed them to a controller.

    From inside its circuit is:
    PROGRESS INSTRUMENTS INC 38005-045-01 REV D FILTER BRD


    THANK YOU VERY MUCH!!
     
  2. PaulEE

    Member

    Dec 23, 2011
    423
    32

    (days later)

    If you don't have a schematic or picture from which we can even begin to guess...we can't tell you much.
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,792
    948
    Timing signals are CRITICAL for the data to have any meaning.

    A 1 microsecond delay in timing will change a radar return by a large percentage of a mile. I think it is about 600 ft.

    Whatever you are wanting to do will be difficult due to the very tight tolerances needed to make RADAR returns useable in real world ways.
     
  4. w2aew

    Member

    Jan 3, 2012
    219
    64
    Note that most of these low power radar guns (like this and the Hot Wheels unit) are 10GHz or higher pulse doppler units. I think the Bushnells use K-band - a little over 20GHz. The reflected signal will be slightly shifted in frequency (Doppler shift). The gun combines the transmitted signal with the reflected signal, and the "beat" frequency is measured. The "beat" frequency is equal to the Doppler shift. At these carrier frequencies, and the speeds for which this radar operates, the "beat" frequency will be in the audio frequency range. So, the gun converts the audio "beat" frequency into speed.

    It's impossible to tell without any additional information whether any usable signals are available from the module you mention, but maybe this gives you an idea what to look for.
     
  5. ronbot

    New Member

    Jun 7, 2012
    2
    0
    X-Band radar Doppler shift is 31.389Hz / MPH. (this is for the USA Police radar band of 10.525GHz)

    When I was initially designing/prototyping the Bushnell from their original concept, I used parts left over from my days at MPH Inc., where I was on the police radar design team. I left the design company before the Bushnell product was finalized, but I believe it stayed at 10.525

    If you have a way to feed that audio frequency into a Counter, then divide it by 31.389 - you'd have the MPH. (measure the period of the analog signal, then average several cycles together to filter noise)
     
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