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High end Radar receiver sensitivities

  1. Jul 7, 2017 #1
    I am looking for what the high end radar receivers can achieve in terms of sensitivity? I have had trouble finding examples online, I have seen -100 to -103dBm as typical sensitivities, but I'm looking for the cutting edge stuff. I've also seen the GPS satellites also have a sensitivity of around -125dBm.
    This is because I am looking for comparisons with a MW sensor that my group is designing that could have sensitivities between -113 - -173dBm at 12.6GHz
     
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  3. Jul 7, 2017 #2

    berkeman

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    Staff: Mentor

    That would depend on the size of the receiving dish antenna, no?
     
  4. Jul 7, 2017 #3
    The large differences between the examples you are quoting is caused by differences in the noise bandwidth. Pn = kTB.
     
  5. Jul 7, 2017 #4

    davenn

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    Really ? the satellites are basically transmit .... I assume you really meant the earth based receivers ?


    the main issue with useable sensitivities below -120 dBm is the local noise floor
    As in, there is no point in having a receiver that achieve a sensitivity of -160 to -170 dBm
    if the local noise floor is around -140 dBm
     
  6. Jul 8, 2017 #5
    Further to my comment, "sensitivity" is meaningless unless the bandwidth is quoted.
    To obtain the sensitivity of the overall receiver, we need to know the antenna noise temperature, receiver noise temperature, bandwidth, and detection threshold.The latter will depend on the type of modulation, type of detector and the desired minimum Bit Error Ratio or S/N. In some cases it will also require knowledge of interferers.
    For these reasons, the simple and traditional way of comparing receiver front ends is by stating noise temperature, noise factor in dB or noise figure.
     
  7. Jul 8, 2017 #6

    Baluncore

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    Marine and ground based radar is not limited by sensitivity but by the ability to correlate the received signal with the signal that was transmitted earlier. That requires a wide bandwidth, a more accurate clock reference and better signal processing.

    Because radar requires a wide bandwidth to accurately separate targets, you need to consider the sensitivity of your receiver when operated with a BW of between 10MHz and 100MHz.

    It is already the case that radar receiver performance is limited by man-made and natural sources of in-band RF energy. Range is limited by the distance to the microwave horizon, not by RX sensitivity. Aircraft, rainfall or hail on the horizon will increase the noise floor because more energy will be scattered from other sources to your receiver. Higher sensitivity and cooled receiver front-ends are only needed when you have satellites or the moon as your target.

    You only need to increase receiver sensitivity if you want to lower the transmit power. That pushes the situation towards making you more vulnerable to sources of interference and hostile jamming.
     
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