US 6,661,292 B2Granted

Apparatus and method for demodulating a radio data system (RDS) signal

AssigneeHarman/Becker Automotive Systems (Becker Division) GmbH

InventorsStefan Gierl, Christoph Benz

Life of this patent

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Abstract

To demodulate the RDS signal, the stereo-multiplex signal is multiplied in a first branch by the in-phase component of an oscillator filtered by a low-pass filter while decimated in its sampling rate and filtered by a high-pass filter while in a second branch it is multiplied by the quadrature component of the oscillator filtered by a low-pass filter decimated in its sampling rate, and filtered by a high-pass filter. An error signal to control the oscillator is calculated from the high-pass-filtered signals and the RDS bit clock. A clock generator generating the RDS bit clock is controlled by the first high-pass-filtered signal and by the oscillator. An RDS decoder, to whose input the first high-pass-filtered signal is applied. and an arithmetic unit which calculates the error signal from the high-pass-filtered signals and from the PDS bit clock are both clocked by the clock generator. The RDS data are retrievable from the output of the RDS decoder.

Claims29

Dependent claims

A phase-locked loop circuit for demodulating a Radio Data System (RDS) signal superimposed on an ARI signal component of a stereo-multiplex signal, the circuit comprising:

an oscillator that generates an in-phase component signal and a quadrature component signal of the carrier of the RDS signal;
a first circuit branch comprising a first multiplier having a first input at which a sampled stereo-multiplex signal is received and a second input at which the in-phase component signal is received, a first low-pass filter having an input connected to an output of the first multiplier, a first divider having an input connected to an output of the first low-pass filter, and a first high-pass filter having an input connected to an output of the first divider;
a second circuit branch comprising a second multiplier having a first input at which the sampled stereo-multiplex signal is received, and a second input at which the quadrature component signal is received, a second low-pass filter having an input connected to an output of the second multiplier, a second divider having an input connected to an output of the second low-pass filter, and a second high-pass filter having an input connected to an output of the second divider;
a feedback branch comprising an arithmetic unit having first and second inputs connected to outputs of the first and second high-pass filters, respectively, a clock input at which an RDS bit clock signal is received, and an output at which the arithmetic unit generates an error signal;
a filter having an input at which it receives the error signal, and an output at which it generates a filtered error signal;
a control unit having an input connected to the filter output, and an output connected to a control input of the oscillator at which the control unit generates a control signal in response to the filtered error signal;
a clock generator having a first control input connected to the output of the first high-pass filter, a second control input connected to an output of the oscillator, and an output at which the clock generator generates the RDS bit clock signal;
and
an RDS decoder having a first input connected to the output of the first high-pass filter, a clock input at which the RDS bit clock signal is received, and an output from which RDS data is retrievable.

6 more elements

A method for demodulating a Radio Data System (RDS) signal superimposed on an ARI signal component of a stereo-multiplex signal, the method comprising:

generating an in-phase component signal and a quadrature component signal of the carrier of the RDS signal;
multiplying a sampled stereo-multiplex signal by the in-phase component to generate a first product signal;
low-pass filtering the first product signal to generate a first low-pass filtered signal;
decimating the first low-pass-filtered signal by a first presettable division factor to generate a decimated filtered first product signal;
high-pass filtering the decimated filtered first product signal to generate a first high-pass-filtered signal;
decoding the first high-pass filtered signal to generate RDS data;
multiplying the sampled stereo-multiplex signal by the quadrature component to generate a second product signal;
low-pass filtering the second product signal to generate a second low-pass filtered signal;
decimating the second low-pass-filtered signal by a second presettable division factor to generate a decimated;
filtered second product signal;
high-pass filtering the decimated filtered second product signal to generate a second high-pass-filtered signal;
calculating an error signal representing a phase difference between the carrier of the RDS signal and the output signal of an oscillator based on the first and second high-pass-filtered signals and an RDS bit clock signal, wherein the error signal represents a phase difference between the carrier of the RDS signal and the output signal of the oscillator;
and
generating a correction signal for controlling the oscillator based on the error signal.

11 more elements

A phase-locked loop circuit for demodulating a Radio Data System (RDS) signal superimposed on an ARI signal component of a stereo-multiplex signal, the circuit comprising:

oscillator means for generating an in-phase component signal and a quadrature component signal of an RDS carrier signal in response to an oscillator control signal;
means for generating a first product signal of a sampled stereo-multiplex signal and the in-phase component signal;
means for generating a second product signal of a sampled stereo-multiplex signal and the quadrature component signal;
means, responsive to a RDS clock signal and signals indicative of said first product signal and said second product signal, for providing said oscillator control signal to controll the oscillator means based on the phase relationship between the RDS carrier signal and the signals generated by the oscillator;
and
means, responsive to said RDS clock signal and a signal indicative of said first product signal, for generating RDS data.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/096,342Filed 11 Mar 2002
Priority: DE 101 11 59010 Mar 2001
Published: US 2002/0140515 A13 Oct 2002
Granted: 9 Dec 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H04H 40/18
Arrangements specially adapted for receiving broadcast information: arrangements characterised by circuits or components specially adapted for…
H04H 40/54
For FM stereophonic broadcast systems receiving: generating subcarriers
H04H 20/34
By plural channels: using an out-of-band subcarrier signal
H04H 2201/13
Characterised by the type of broadcast system: radio data system/radio broadcast data system [RDS/RBDS]