R&S FSQ Signal Analyzer - Rohde & Schwarz

R&S FSQ Getting Started
Measurements on Modulated Signals
modulation spectrum will work because the burst edges are blanked out for the
measurement by means of the Gated Sweep function. The R&S FSQ performs
measurements only if the modulation spectrum is continuous when the burst is on.
However, the IBW method fails for the spectrum created by the burst edges. As the
measurement is carried out with resolution bandwidths that are very small compared
to the signal bandwidth, a spurious amplitude distribution is obtained in the defined
measurement channel because of the resolution bandwidth. The small resolution
bandwidth cannot settle to the peak amplitudes of the test signal. This problem is
avoided in the R&S FSQ by performing time domain measurements with the root
raised cosine filter specified in the IS136 standard.
If the peak detector is used instead of the default RMS detector (which is selected
when the standard is selected), the true adjacent channel power generated by the
burst edges can also be measured.
Test setup
The test setup for this example and the settings for R&S SMIQ are identical to those
described in “Measurement Example 3 – Measuring the Modulation Spectrum in
Burst Mode with the Gated Sweep Function” on page 2.42.
Measurement with the R&S FSQ
1. Set the R&S FSQ to the analyzer mode.
➢ Press the SPECTRUM key.
The R&S FSQ is in the analyzer mode.
2. Synchronize the R&S FSQ to an external reference frequency.
➢ Press the SETUP key.
➢ Set the REFERENCE softkey to EXT.
3. Set the center frequency to 850 MHz
➢ Press the FREQ key and enter 850 MHz.
4. Configure the adjacent channel power measurement for IS136 signals in
Fast ACP mode.
➢ Press the MEAS key.
➢ Press the CHAN PWR ACP � softkey.
➢ Press the CP/ACP STANDARD softkey.
➢ Select NADC IS136 from the list of standards and press ENTER.
➢ Press the CP/ACP CONFIG � softkey.
➢ Set the FAST ACP softkey to ON.
The R&S FSQ performs the power measurement in 5 channels (in the useful
channel and in the two upper and lower adjacent channels).
5. Set the optimum reference level and RF attenuation for the measurement.
➢ Press the ADJUST REF LEVEL softkey.
The R&S FSQ sets the optimum RF attenuation and the optimum reference
level on the basis of the measured channel power.
Operating Manual 1313.9681.12 - 01 2.45