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  1. #1

    Default What does a radar detector detect? ;)

    Ok, I know this has the possibility to devolve into "Who's burried in Grant's tomb?", but it is a serious question.

    First, let me say that I am an electrical engineer, and I am into ham radio and scanning. So my question isn't as silly as it sounds.

    I know that speed measurement radar measures pulses of radio waves at various frequencies.

    Do radar detectors simply detect a signal/energy at a specific frequency band? Or do they look for specific patterns within a signal (e.g. pulse rates, etc)?

    Would a simple signal at 34.7GHz trigger a radar detector? Or would the signal need to be 'pulsed' as it is in a radar device?

    Thanks!

  2. #2
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    Default Re: What does a radar detector detect? ;)


  3. #3
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    Lightbulb Re: What does a radar detector detect? ;)

    Quote Originally Posted by b52hbuff View Post
    Ok, I know this has the possibility to devolve into "Who's burried in Grant's tomb?", but it is a serious question.

    First, let me say that I am an electrical engineer, and I am into ham radio and scanning. So my question isn't as silly as it sounds.

    I know that speed measurement radar measures pulses of radio waves at various frequencies.

    Do radar detectors simply detect a signal/energy at a specific frequency band? Or do they look for specific patterns within a signal (e.g. pulse rates, etc)?

    Would a simple signal at 34.7GHz trigger a radar detector? Or would the signal need to be 'pulsed' as it is in a radar device?

    Thanks!
    Im not 100% Sure if i understand your Question here but i believe a Radar detector would sound and alert if it detects a radar beam on a certain ban like Ka ban and if it was transmitting on the ban or Frequently range.

    Does this Answer your question

  4. #4
    snoopyc4
    Guest

    Default Re: What does a radar detector detect? ;)

    RDs are built around a superheterodyne receiver, which has a local oscillator that radiates slightly. A radar detector detector (RDD) detects these emissions.

  5. #5
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    Default Re: What does a radar detector detect? ;)

    Quote Originally Posted by b52hbuff View Post
    I know that speed measurement radar measures pulses of radio waves at various frequencies.
    Speed measurement radar used in law enforcement uses CW radar with the doppler principle.


    Quote Originally Posted by b52hbuff View Post
    Do radar detectors simply detect a signal/energy at a specific frequency band? Or do they look for specific patterns within a signal (e.g. pulse rates, etc)?

    Would a simple signal at 34.7GHz trigger a radar detector? Or would the signal need to be 'pulsed' as it is in a radar device?
    Radar detectors are designed to detect unmodulated CW radar in the advertised bands of operation.

    If there happens to be a modulated or pulsed signal at those frequencies, a radar detector may or may not alert to those signals as well, depending on the frequency and how it is modulated. Some models have been specifically designed to not alert to certain types of modulated radar signals (such as FMCW), which are not used by law enforcement.

  6. #6
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    Default Re: What does a radar detector detect? ;)

    Do radar detectors simply detect a signal/energy at a specific frequency band?
    Yes, frequencies and bands

    They generally do not look for information but this can be part of the filtering process used to ignore falses.

    Some Laser Detectors look for specific information on the specific detected frequency or band(s) This information can be the signature of the gun in use.

  7. #7

    Default Re: What does a radar detector detect? ;)

    Jimbonzzz wrote :

    ''If there happens to be a modulated or pulsed signal at those frequencies, a radar detector may or may not alert to those signals as well, depending on the frequency and how it is modulated.''

    Are'nt all of the actual police radars pulsed ?

    Is it exact to think that the police radars use CW wave but is
    chopped in miniburst . If so , assuming each manufacturer
    use his own pulse repetition frequency ,PRF , would it be
    possible for a detector to identify the brand ?

    Thanks Professor .
    O divine art of subtlety and secrecy!
    Through you we learn to be invisible, through you inaudible;
    and hence hold the enemy's fate in our hands.

    -- Sun Tzu, The Art of War, c. 500bc

  8. #8

    Default Re: What does a radar detector detect? ;)

    Quote Originally Posted by jimbonzzz View Post
    Speed measurement radar used in law enforcement uses CW radar with the doppler principle.

    [snip...]

    Radar detectors are designed to detect unmodulated CW radar in the advertised bands of operation.

    If there happens to be a modulated or pulsed signal at those frequencies, a radar detector may or may not alert to those signals as well, depending on the frequency and how it is modulated. Some models have been specifically designed to not alert to certain types of modulated radar signals (such as FMCW), which are not used by law enforcement.
    Thanks for setting me straight. I was reading about LIDAR and RADAR and got the operation backward. Looks like LIDAR is pulsed and RADAR is CW as you have said...



    So next question... Given that a radar detector has one receiver that must be tuned to one of several frequencies when detecting a signal... How long do units 'monitor' a specific frequency before moving on to the next one?

  9. #9
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    Default Re: What does a radar detector detect? ;)

    Think of a Radar Detector as a radio scanner that only scans a handful of frequencies, but does it very efficiently and with filtering for false alerts. If it finds a source in that range and thinks it's important you know about it, it alerts. See here for a little more detailed info: [ame="http://en.wikipedia.org/wiki/Radar_detector"]Wikipedia's article on Radar Detectors[/ame].

    As for how long it takes to scan each band, well it varies but typically less than 1 second to scan all bands. All manufacturers have their own formulas for the order that bands get scanned (sometimes depending on the mode). The Valentine 1 is generally regarded as the fastest in this regard, however.
    Last edited by zerbey; 01-04-2010 at 08:16 PM. Reason: I can't spell

  10. #10
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    Default Re: What does a radar detector detect? ;)

    [QUOTE=zerbey;658245]Think of a Radar Detector as a radio scanner that only scans a handful of frequencies, but does it very efficiently and with filtering for false alerts. If it finds a source in that range and thinks it's important you know about it, it alerts. [QUOTE]

    Now that makes sense to me. Then I guess it will process a signal providing visual and a programed audio to correspond. Sounds good anyway.

 

 

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