Electrical audio signal processing systems and devices – Binaural and stereophonic – Broadcast or multiplex stereo
Patent
1995-02-16
1997-01-07
Chan, Jason
Electrical audio signal processing systems and devices
Binaural and stereophonic
Broadcast or multiplex stereo
381 7, 381 13, H04H 500
Patent
active
055925570
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to radio receivers, in particular, to a radio receiver with digital signal processing.
BACKGROUND INFORMATION
Processors for digital signal processing are known that are programmable for specific tasks. Thus signal processing tasks such as addition or multiplication of the individual sampled values of the digital signals, but also considerably more complex tasks such as digital filtering, can be performed. In a radio receiver many different signals are present, which must be processed almost simultaneously in the case of a configuration with one or more digital signal processors. Thus a very high level of computing power is required of the signal processors.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a radio receiver with digital signal processing wherein the capabilities of the circuits present, specifically of signal processors, are optimally utilized for digital signal processing.
This goal is achieved by the present invention by derived therefrom in digital form with a first sampling rate, multiplex signal with a second sampling rate that is lower than the first sampling rate, first sampling rate, and processed subsidiary signals serving as control signals with the first sampling rate.
In the radio receiver of the present invention, the capability of a digital signal processor is made use of in an especially advantageous manner so that not only the basic functions of the radio receiver, i.e., receiving and demodulating audio signals, are performed, but also other functions are possible, for example, matching the signal processing to the quality of the signals received.
In increasing the sampling rate of the processed subsidiary signals, aliasing noise may occur. If this noise is noticeable in the reproduced audio signals, a further improvement of the present invention provides for low-pass filtering immediately after increasing the sampling rate of the processed subsidiary signals to the first sampling rate.
Noise can be detected in the received stereo multiplex signal in a further improvement of the present invention by deriving a first subsidiary signal, which contains spectral components of the stereo multiplex signal between the upper limit of the useful frequency range of the stereo multiplex signal and the first sampling rate, and reducing its sampling rate to the second sampling rate.
Another possibility for detecting noise is provided by another improvement by obtaining a symmetry signal in quadrature in relation to the (L-R) difference band during stereo encoding, which forms the second subsidiary signal via a low-pass filter and sampling rate reduction to the second sampling rate.
Furthermore, the incoming signal level is important for evaluating the quality of a signal and as information for a transmitter scan or test reception from alternative transmitters. In another improvement, the incoming signal level is measured by producing a third subsidiary signal from an amplitude-modulated FM intermediary frequency signal via low-pass filtering and sampling rate reduction.
An advantageous derivation of control signals in the radio receiver of the present invention is possible by producing, via a combination of the subsidiary signals, a first control signal affecting the stereo channel separation and a second control signal reducing the volume of the reproduced useful signals in the case of noise.
Another improvement of the present invention consists of having an integer ratio between the first and second sampling rates. The first sampling rate is preferably 228 kHz and the second sampling rate 9.5 kHz.
The use of a tuner which is at least partially digital is possible in an advantageous manner when the stereo multiplex signal can be supplied from a receiving means in digital form with a third sampling rate, which is higher than the first sampling rate and is preferably twice the first sampling rate.
In an advantageous embodiment of the radio receiver of the present invention, suitable signal processing via
REFERENCES:
patent: 4379207 (1983-04-01), Kubota
patent: 4827515 (1989-05-01), Reich
patent: 5357544 (1994-10-01), Horner et al.
Reich et al., "Digital FM-Stereo Demodulation and Decoding", Signal Processing IV: Theories and Applications, Bd. 2, 8, Sep. 1988, Grenoble, France, pp. 499-502, XP93955.
Bakhru, "Communications Receiver Design Using Digital Processing", Digital Signal Processing, Bd, 2, Nr. 1, Jan. 1992, Orlando, Florida, U.S., pp. 2-13, XP387796.
Chahabadi Djahanyar
Herrmann Matthias
Kaesser Juergen
Vogt Lothar
Blaupunkt-Werke GmbH
Chan Jason
Chang Vivian W.
LandOfFree
Radio receiver with digital signal processing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radio receiver with digital signal processing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radio receiver with digital signal processing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1771688