Ceyear 3943B, Руководство по эксплуатации

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Appendix
146
PdBm = -FdB+10LogB
Where:
PdBm - the sensitivity of the monitoring receiver
FdB - noise factor of the monitoring receiver
B - 3dB bandwidth (in Hz) of the monitoring receiver
Phase noise
The oscillator in the monitoring receiver is used to convert the input signals of different frequencies to the
intermediate frequency. The phase noise represents the relative value of the noise power and carrier
power in the 1 Hz equivalent noise bandwidth at a certain frequency offset of the carrier, which is
commonly expressed in dBc/Hz . It is a measure of the oscillator's short-term frequency stability, which is
caused by phase or frequency variations, and is expressed as a bell-like noise characteristic in the
oscillator signal. It affects the measurement ability of the whole machine to the phase noise of the
measured signal, and also affects the sensitivity and dynamic range of the whole machine.
Gain compression
If the input signal level is increased, the mixer circuit, amplifier and other unit circuits of the monitoring
receiver may work close to the saturation point. At this time, the output signal component no longer
changes linearly with the input signal, and the displayed signal level is low, which is caused by gain
compression. An 1dB (or 0.5dB) expression point is expressed typically with the input level
corresponding to the output linear value deviation of 1dB (or 0.5dB).