R&S ESU Series - Page 128

Operating Manual 1302.6163.12 - 03 4.97
R&S ESU Instrument Functions
APD Mode
Fig. 4.30 Zero span of a pulsed signal (single or low PRF)
Fig. 4.31 APD of a pulsed signal (single or low PRF)
Next, let us consider the case that the repetition frequency of the impulse increases
as shown in Fig. 4.32. The disturbance shown in Fig. 4.32 has a higher average
value than Fig. 4.30 because of the increasing pulse repetition frequency, but the
log-average value (X
avg
) of Fig. 4.32 does not show any difference from that of Fig.
4.30. This is because the log-average value mainly depends on the receiver noise
and strongly suppresses impulsive noise in this case. But the APD of the distur-
bance, shown in Fig. 4.33, has high sensitivity to variation in the average value.
Clearly the probability presented in Fig. 4.33 increases when compared with Fig.
4.31.