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E4D14

AMATEUR PRACTICES · Receiver performance characteristics: dynamic range; intermodulation and cross-modulation interference; third-order intercept; desensitization; preselector; sensitivity; link margin

E4D14E4D →

What power level does a receiver minimum discernible signal of -100 dBm represent?

  1. A100 microwatts
  2. B0.1 microwatt
  3. C0.001 microwatts
  4. D0.1 picowatts
Why dBm is power referenced to 1 milliwatt, so 0 dBm = 1 mW = 10^-3 W. Each 10 dB step changes power by a factor of 10, so -100 dBm is 10 decades below 1 mW: 10^-10 mW, which equals 10^-13 W. Since 1 picowatt is 10^-12 W, that works out to 0.1 pW, an extremely weak but typical MDS figure for a good HF receiver.
Watch out The choice of 0.001 microwatt is 1 nanowatt, or 10^-9 W, which is only -60 dBm; it is off by four decades because the count of 10 dB steps was cut short.
0 dBm = 1 mW; every 10 dB moves the decimal one place. -100 dBm = 10 decades down = 0.1 pW.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
← E4D13 All of E4D

The rest of E4D

  1. E4D01 What is meant by the blocking dynamic range of a receiver?
  2. E4D02 Which of the following describes problems caused by poor dynamic range in a receiver?
  3. E4D03 What creates intermodulation interference between two repeaters in close proximity?
  4. E4D04 Which of the following is used to reduce or eliminate intermodulation interference in a repeater caused by a …
  5. E4D06 What is the term for the reduction in receiver sensitivity caused by a strong signal near the received freque…
  6. E4D07 Which of the following reduces the likelihood of receiver desensitization?
  7. E4D08 What causes intermodulation in an electronic circuit?
  8. E4D09 What is the purpose of the preselector in a communications receiver?
  9. E4D10 What does a third-order intercept level of 40 dBm mean with respect to receiver performance?
  10. E4D11 Why are odd-order intermodulation products, created within a receiver, of particular interest compared to oth…
  11. E4D12 What is the link margin in a system with a transmit power level of 10 W (+40 dBm), a system antenna gain of 1…
  12. E4D13 What is the received signal level with a transmit power of 10 W (+40 dBm), a transmit antenna gain of 6 dBi, …
  13. E4D14 What power level does a receiver minimum discernible signal of -100 dBm represent?
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