4. What happens to the noise floor of a spectrum analyzer when the input filter resolution bandwidth is decreased by two decades?
b) 20 dB decrease
The input filter bandwidth determines the amount of power that will be present at the detector circuitry. Since the detector performs a power integration function, it sums all of the incident power across the band. Decreasing the bandwidth by a factor of 100 (two decades) allows one one-hundredth of the amount of power to reach the detector, which in term of decibels is:
10*log( 1/100) = -20 dB.
two decades=100?????????????????????????????
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发表于 2008-6-30 18:45:00
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