R&S FSQ Signal Analyzer - Rohde & Schwarz

R&S FSQ Instrument Functions
Analyzer Mode
Some of the measurement specifications (e.g. PDC, RCR STD-27B) require measurement
of the occupied bandwidth using a peak detector. The detector setting of
the R&S FSQ has to be changed accordingly then.
Example
Measurement of occupied bandwidth of a PDC signal at 800 MHz, level 0 dBm
[PRESET] Set the R&S FSQ to the default setting.
[FREQ: CENTER: 800
MHz]
Set the center frequency to 800 MHz.
[AMPT: 0 dBm] Set the reference level to 0 dBm.
[MEAS] Call the menu for the measurement functions.
[OCCUPIED
BANDWIDTH]
[% POWER
BANDWIDTH: 99%]
[CHANNEL
BANDWIDTH: 21 kHz]
Select measurement of the occupied bandwidth and open
the submenu for configuring the measurement.
Select 99% for the bandwidth to be measured.
Enter the channel bandwidth of 21 kHz specified by PDC.
[ADJUST SETTINGS] Optimize the measurement parameters for the specified
channel bandwidth.
Allow for a complete frequency sweep so that the
R&S FSQ can determine the total signal power.
[ADJUST REF LVL] Adjust the reference level to the measured signal power.
[TRACE: DETECTOR: PDC requires measurement of the occupied bandwidth
using a
DETECTOR MAX PEAK] peak detector. Therefore, switch on the peak detector
instead of the RMS detector selected by ADJUST SET-
TINGS.
4.5.13.4 Measurement of Signal Amplitude Statistics
Digital modulated signals are similar to white noise within the transmit channel, but
are different in their amplitude distribution. In order to transmit the modulated signal
without distortion all amplitudes of the signal have to be transmitted linearly, e.g.
from the output power amplifier. Most critical are the peak amplitude values, of
course.
Degradation in transmit quality caused by a transmitter two port network is dependent
on the amplitude of the peak values as well as on their probability.
The probability of amplitude values can be measured with the APD function (Amplitude
Probability Distribution). During a selectable measurement time all occurring
amplitude values are assigned to an amplitude range. The number of amplitude values
in the specific ranges is counted and the result is displayed as a histogram.
Each bar of the histogram represents the percentage of measured amplitudes within
the specific amplitude range.
4.108 Operating Manual 1313.9681.12 - 01