Radio broadcasting system with transmitter identification
First Claim
1. A transmitter for a radio broadcasting system with transmitter identification, said transmitter comprising means for providing an audio frequency information signal, a modulator for modulating a stereo information signal on a suppressed stereo subcarrier, an oscillator for generating a stereo pilot whose frequency is located between the frequency spectra of the audio frequency information signal and of the modulated stereo information signal, a source of binary transmitter identification signals, a circuit for deriving from the stereo pilot a further subcarrier whose frequency is a harmonic of a subharmonic of the stereo pilot which is not coinciding with a harmonic of the stereo pilot, a further modulator for binary phase modulating said further subcarrier with the transmitter identification signal, and a combination circuit for combining the modulated transmitter identification signal with the audio information signal, the stereo information signal and the stereo pilot.
0 Assignments
0 Petitions
Accused Products
Abstract
FM radio broadcasting system with transmitter identification by means of a transmitted subcarrier whose frequency is a harmonic of subharmonic of the stereo pilot and which is binary phase modulated with transmitter identification signals. In the transmitter the subcarrier is locked to the stereo pilot and the unmodulated wave, which is required for detection of the transmitter identification signal, is derived in the receiver from the received stereo pilot.
-
Citations
7 Claims
- 1. A transmitter for a radio broadcasting system with transmitter identification, said transmitter comprising means for providing an audio frequency information signal, a modulator for modulating a stereo information signal on a suppressed stereo subcarrier, an oscillator for generating a stereo pilot whose frequency is located between the frequency spectra of the audio frequency information signal and of the modulated stereo information signal, a source of binary transmitter identification signals, a circuit for deriving from the stereo pilot a further subcarrier whose frequency is a harmonic of a subharmonic of the stereo pilot which is not coinciding with a harmonic of the stereo pilot, a further modulator for binary phase modulating said further subcarrier with the transmitter identification signal, and a combination circuit for combining the modulated transmitter identification signal with the audio information signal, the stereo information signal and the stereo pilot.
- 3. A receiver for the reception of radio broadcasting signals with transmitter identification wherein a main carrier is frequency modulated by a multiplex signal comprising an audio frequency information signal, a stereo information signal modulated on a suppressed stereo subcarrier, a stereo pilot, and a binary transmitter identification signal which is binary phase modulated on a further subcarrier which is a harmonic of a subharmonic of the stereo pilot not coinciding with a harmonic of the stereo pilot, said receiver comprising a frequency discriminator for demodulating the received main carrier, a synchronous demodulator having first and second inputs and an output, a first transmission path coupled to the output of the discriminator for applying the binary phase modulator transmitter identification signal to the first input of the synchronous demodulator, a second transmission path coupled to the output of the frequency discriminator for applying an unmodulated wave synchronized by the stereo pilot to the second input of the synchronous demodulator, and and output circuit coupled to the output of the synchronous demodulator for the demodulated transmitter identification signal.
Specification