R&S FSL Fast Level Measurement Using Frequency Lists
1300.2519.12 7.19 E-11
Fast Level Measurement Using Frequency Lists
A typical task for the R&S FSL is power measurement at a number of frequency points, e.g. at multiples
of the fundamental (harmonics measurement), or at frequencies defined by a mobile radio standard
(e.g. spectrum due to transients at ± 200 kHz, ± 400 kHz, etc about the carrier frequency of a GSM
signal). In many cases, different level and/or bandwidth settings are required for the different frequency
points to match the channel spacing and meet the requirements of dynamic range.
Especially for this application, the R&S FSL offers a number of remote–control functions (commands
available in SENSe:LIST subsystem) that allow level measurement based on a frequency list with
different instrument settings assigned to different frequencies. Not only the frequency list can be
programmed, but also the measurement types (PEAK, RMS, AVG) to be performed simultaneously can
be selected.
The example below describes a harmonics measurement on a dual–band amplifier. The harmonics
level in general decreases as the frequency increases. To boost measurement sensitivity, therefore, the
reference level is lowered by 10 dB from the third harmonic.
The following settings are used:
Reference level: 10.00 dBm up to first harmonic, 0 dBm from 2nd harmonic
RF attenuation: 20 dB
Electronic attenuation: 0 dB (OFF)
Filter type: NORMal
RBW: 1 MHz
VBW: 3 MHz
Measurement time: 300 µs
Trigger delay: 100 µs
Trigger: video, 45 %
Frequency Type
935.2 MHz GSM 900 fundamental
1805.2 MHz GSM 1800 fundamental
1870.4 MHz GSM 900 2nd harmonic
2805.6 MHz GSM 900 3rd harmonic
3610.4 MHz GSM 1800 2nd harmonic
3740.8 MHz GSM 900 4th harmonic
5815.6 MHz GSM 1800 3rd Harmonic
The frequencies are selected in ascending order to minimize system–inherent waiting times resulting
from frequency changes.
At each frequency point the peak power and the rms power are measured. The peak power and the rms
power values are stored alternately in the results memory.
REM ************************************************************************
Public Sub FrequencyList()
result$ = Space$(500)
'––––––––– R&S FSL default setting ––––––––––––––––––––––––––––––––––––––––
CALL SetupStatusReg 'Configure status register
CALL InstrWrite(analyzer,"*RST") 'Reset instrument
CALL InstrWrite(analyzer,"INIT:CONT OFF") 'Single sweep mode
CALL InstrWrite(analyzer,"SYST:DISP:UPD OFF")
'Display off
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