Spectrum Measurements
R&S
®
ESR
228User Manual 1175.7068.02 ─ 12
Figure 6-2: Measuring the channel power and adjacent channel power ratio for CDMA2000
1X signals
with zero span (Fast ACP)
Assuming a measurement with five channels (1 channel plus 2 lower and 2 upper adja-
cent channels) and a sweep time of 100 ms, a measurement time per channel of 20
ms is required. The number of effective samples taken into account for power calcula-
tion in one channel is the product of sweeptime in channel times the selected resolu-
tion bandwidth.
Assuming a sweeptime of 100 ms, there are (30 kHz / 4.19 MHz) * 100 ms * 10 kHz ≈
7 samples. Whereas in Fast ACLR mode, there are (100 ms / 5) * 30 kHz ≈ 600 sam-
ples. Comparing these numbers explains the increase of repeatability with a 95% confi-
dence level (2δ) from ± 2.8 dB to ± 0.34 dB for a sweeptime of 100 ms (as shown in
Figure 6-3 and ).
For the same repeatability, the sweep time would have to be set to 8.5 s with the inte-
gration method. The Figure 6-4 shows the standard deviation of the results as a func-
tion of the sweep time.
Measurements
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