R&S FSL Measurements on Modulated Signals
1300.2519.12 2.29 E-11
ACPR IS95 Repeatability
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
10 100 1000
S
weep tim e/m s
Standard dev /dB
T
x channel
Fig. 2-22 Repeatability of adjacent channel power measurements on CDMA 2000 signals in
the fast ACP mode
Note on adjacent channel power measurements on 2000 MC1 base–station signals:
When measuring the adjacent channel power of 2000 MC1 base–station signals, the frequency spacing
of the adjacent channel to the nominal transmit channel is specified as ±750 kHz. The adjacent
channels are, therefore, so close to the transmit channel that the power of the transmit signal
leaks across and is also measured in the adjacent channel if the usual method using the 30
kHz resolution bandwidth is applied. The reason is the low selectivity of the 30 kHz resolution
filter. The resolution bandwidth, therefore, must be reduced considerably, e.g. to 3 kHz to avoid
this. This causes very long measurement times (factor of 100 between a 30 kHz and 3 kHz
resolution bandwidth).
This effect is avoided with the zero span method which uses steep IF filters. The 30 kHz channel filter
implemented in the R&S FSL has a very high selectivity so that even with a ± 750 kHz spacing
to the transmit channel the power of the useful modulation spectrum is not measured.
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