
Estimating the Discriminator Constant
The Phase Detector Constant can be estimated directly from the R port
input power level. (Providing the power level requirements for driving
the L port of the phase detector are being met.) A power meter or a
spectrum analyzer can be used to measure the power level. Compare the
measured R port level to the following graph to determine the Phase
Detector Constant.
+
15
L Port Signal Level
i
s
Auumid to b
e
Approximate Phase Noise Floor (dBc/Hz)
Appropriate for the ' ' '
Phase Detector f > "| Q |<H 2
Note:
This relationship assumes a 9 dB conversion loss in the Phase Detector.
Figure 2-22. Estimate of Phase Detector Constant for a Given R Port input Level
An estimate of the Discriminator Constant {KQ) can be derived from an
estimate of the Phase Detector Constant
(K(j>).
The following equation converts the Phase Detector Constant {K^) to a
Discriminator Constant (KD).
K
D
= 2-KTK^
where K$ = Detector Constant
Kjy = Discriminator Constant, and
T
= the delay of the discriminator
2-78 Calibr Process: $N w/FM Discriminator
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