Fm Stereo/Rds Concepts; Fm Stereo; Rds/Rbds - Keysight N9030A Measurement Manual

Concepts

FM Stereo/RDS Concepts

FM Stereo/RDS Concepts

FM stereo is an enhancement of FM by using stereo multiplexing. An FM stereo
signal carries stereophonic programmes in which different contents are transmitted
for L (left) and R (right) audio channels.
RDS (Radio Data System) is the text information such as traffic, weather, and radio
station information carried in FM signals. This information can be displayed on the
screen of the end-user's device.
Figure 2-5
data.
Figure 2-5 Baseband spectrum of the FM Stereo/RDS signal
Amplitude

FM Stereo

The FM stereo multiplexed signal consists of a mono (L+R) signal, a stereo (L-R)
signal, and a pilot signal.
As shown in
baseband spectrum (50 Hz ~ 15 kHz) to keep backward compatibility with the
previously monophonic FM systems. The (L-R) signal is amplitude modulated onto
a suppressed subcarrier at 38 kHz. A pilot signal is transmitted at 19 kHz and is used
by the receiver to identify a stereo transmission and reconstruct L and R audio
signals from the multiplexed signal.
In the receiver, the (L+R) signal is added to the (L-R) signal to get the L signal, and
subtracts the (L-R) signal to get the R signal.

RDS/RBDS

The standard documents for RDS and RBDS are as follows:
• IEC 62106: Specification of the radio data system (RDS) for VHF/FM sound
• EIA/NAB NRSC: United States RBDS standard - Specification of the radio
shows the baseband spectrum of the FM stereo signal including RDS
Stereo signal
Mono
signal
L+R
Pilot
15 19
Figure 2-5, the mono (L+R) signal occupies the lower part of the
broadcasting in the frequency range from 87.5 to 108.0 MHz.
broadcast data system (RBDS).
L-R
RDS/RBDS
38 57
Frequency (kHz)
30