Demodulating An Fm Stereo/Rds Signal Using The Analyzer As A Fixed Tuned Receiver (Time-Domain) - Keysight N9030A Measurement Manual

Concepts

Demodulating an FM Stereo/RDS Signal Using the Analyzer as a Fixed Tuned Receiver (Time-Domain)

Demodulating an FM Stereo/RDS Signal Using the Analyzer as a Fixed
Tuned Receiver (Time-Domain)
FM Stereo/RDS signal contains mono part, stereo part, RDS/RBDS, and pilots. The
process of demodulating FM Stereo/RDS signal is more complicated than simple FM
signal and is described as below.
1. Perform the FM demodulation to obtain the baseband modulating signal. The
Figure 2-8 Baseband modulating signals of the FM Stereo/RDS signal
Amplitude
2. Recover the L (left channel) and R (right channel) of the audio signal.
3. Multiply the 19 kHz pilot to recover the 57 kHz subcarrier, demodulate the RDS
4. Apply the de-emphasis or audio filters including highpass, lowpass, bandpass
5. Calculate measurement parameters like SINAD, Distortion, THD and so on.
demodulating method is the same to
Analyzer as a Fixed Tuned Receiver (Time-Domain) on page
The baseband modulating signal should look like
Stereo signal
Mono
signal
L+R
Pilot
15 19
a. Demodulate the L+R part.
b. Extract the 19 kHz pilot and multiply it to recover the 38 kHz subcarrier.
c. Perform the DSBSC (Double-Sideband Suppressed Carrier) AM
demodulation to get the L-R signal.
d. Get the L and R signals from (L-R) and (L+R).
/RBDS bits, and then calculate the BLER.
(CCITT, A-Weighted) filters to the audio signal (L and R).
Demodulating an FM Signal Using the
Figure
L-R
RDS/RBDS
38 57
Frequency (kHz)
34
33.
2-8.