Rohde & Schwarz SML01 - FM Total Harmonic Distortion

R&S®SML / R&S®SMV03 Test sequence
1090.3123.12 10.23 E-6
FM frequency response
Test setup  Test setup 1, demodulator mode
Settings on R&S SML /
R&S SMV03
- LEVEL: 0 dBm
- FREQ: 1 GHz
- MODULATION  FM  FM DEVIATION: 100 kHz
FM SOURCE: LFGen
LFGenFreq = 10 Hz to 100 kHz
Settings on the test receiver - D
emodulation: FM
- D
etector: Peak
Measurement  Determine the modulation frequency response by varying the generator
frequency of the built-in LF generator in the FM menu from 10 Hz to
100 kHz. The modulation frequency response is the difference between
the lowest and highest measured deviation.
Note: Since there is no difference between the frequency response in FM and PhiM, there is no
need to measure the broad FM loop. The broad PhiM loop can be measured on the
spectrum analyzer and this is in fact easier to do.
FM total harmonic distortion
Test setup  Test setup 1, demodulator mode
Settings on R&S SML /
R&S SMV03
- LEVEL: 0 dBm
- FREQ:
605.5 MHz, 650 MHz, 700 MHz, 750 MHz, 807 MHz
- MODULATION  FM  FM DEVIATION: see table
FM SOURCE: LFGen
LFGenFreq = 1 kHz
Settings on the test receiver - D
emodulation: FM
- D
etector: Peak
- Activate THD & SINAD
Measurement  Read off the THD value from the test receiver and use the formula
%100
10
1
20
•=

THD
k
to convert to the total harmonic distortion.
Carrier freq. [MHz] FM deviation [kHz]
50 500
100 75
200 125
400 250