R&S FSQ Signal Analyzer - Rohde & Schwarz

R&S FSQ Getting Started
Standard Deviation / dB
1.4
1.2
Measurements on Modulated Signals
Fig. 2.29 shows the standard deviation of results in the different channels as a
function of the selected sweep time. The standard deviation for the various
sweep times was recorded using a signal generator as a source. With real
DUTs the amplitude distributions in adjacent channels may be different so that
the standard deviation could differ from that shown in Fig. 2.25. Standard
deviation of the results of Fast ACP measurement as a function of selected
sweep time evaluated from 100 measurements per sweep time. To evaluate
the correct measuring time for time-critical measurements at a given standard
deviation, the standard deviation of the ACP values at the output of the real
DUT must be determined.
1
0.8
0.6
0.4
0.2
Tx Channel
NADC Repeatability
Alt1 Channels
Adj Channels
0
10 100 1000
Fig. 2.29 Standard deviation of the results of Fast ACP measurement as a function of
selected sweep time evaluated from 100 measurements per sweep time
2.5.3.3 Measurement Example 3 – Measuring the Modulation Spectrum in Burst Mode
with the Gated Sweep Function
Since transmission systems compliant to IS136 use a TDMA method, the adjacent
channel power must also be measured in burst mode. An IS136 TDMA frame is
divided into 6 time slots. Two of these slots are assigned to a subscriber. This
means that the ratio of transmit time to off-time for IS136 mobile phones is only 1:3
(e.g. time slots 1 and 4)
The R&S FSQ supports the measurement of the adjacent channel power in the
TDMA mode with the Gated Sweep function.
Test setup with the R&S Signal Generator SMIQ
Sweep Time / ms
2.42 Operating Manual 1313.9681.12 - 01