Test Procedures R&S SMB
1407.0806.82 1.36 E-5
Frequency Modulation
Test Methods
Test assembly See section "Standard Test Assembly for Analog Modulations",
page 1.3.
Test Method "FFT
Demodulation (Option FS-K7)"
• The FM deviation and distortion are determined by digital signal
processing in the spectrum analyzer.
Settings on R&S FSQ:
AMPTD / REF LEVEL test level,
FREQ / CENTER test frequency
FMDEMOD,
FMDEMOD ON,
RESULT DISPLAY / FM resp. PM
DEMOD BW > 2 * (deviation + fmod) for FM,
DEMOD BW > 2 * fmod * (1 + deviation) for PM,
RANGE / DEVIATION PER DIV 0.5 * deviation
MEAS TIME 3/fmod
for distortion (up to 3
r
d
harmonic)
RESULT DISPLAY / FM resp. PM / AF SPECTRUM
DEMOD BW > 2 * (deviation + 3.5 * fmod) for FM,
DEMOD BW > 7 * fmod * (1 + deviation) for PM,
MEAS TIME 16/fmod
FM Setting Uncertainty
Test Method
FFT Demodulation (see chapter "Test ")
Measurement
Settings on DUT:
RF On
Level 0 dBm:
Frequency Modulation menu:
State on
FM Source Internal
FM Mode Normal
Recommended settings
Recommended test frequencies: 10 MHz, 1000 MHz
with LFGen Freq = 1 kHz, FM Deviation = 100 kHz
Repeat measurement at 1000 MHz with changing settings to
FM Source External
FM Ext Coupling AC
feed in a 1 kHz, 1Vp external modulation signal at the MOD EXT
connector
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