Electrical audio signal processing systems and devices – Binaural and stereophonic – Broadcast or multiplex stereo
Patent
1995-02-14
1997-08-26
Kuntz, Curtis
Electrical audio signal processing systems and devices
Binaural and stereophonic
Broadcast or multiplex stereo
381 10, H04H 500
Patent
active
056618093
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a radio receiver having digital signal processing.
BACKGROUND INFORMATION
Reception quality can fluctuate heavily, particularly in car radios, due, for example, to multipath reception, the reception of spurious signals, or due to breaks in the received field strength. To keep the resultant interference as low as possible, various measures have been disclosed for masking this interference in the audio signal. It is, for example, possible in the case of a poor reception, to temporarily attenuate the audio signals or to reduce the stereo channel separation. These measures presuppose that interference in the received signal can be perfectly determined.
The object of the present invention is to disclose a radio receiver having digital signal processing, in the case of which interference in the received signal, in particular such interference which also leads to audible interference, is recognized and, from that, signals are derived for controlling the reproduction of the audio signals.
SUMMARY OF THE INVENTION
This objective is solved according to the present invention in stereo multiplex signal, the first auxiliary signal being dependent upon the existence of signal components whose frequency lies above the fundamental (useful) frequency range of the stereo multiplex signal, and the second auxiliary signal being dependent upon the symmetry of the sidebands of the stereo subcarrier; interference signal indicating the existence of interference; and influence the audio signals acquired by decoding the stereo multiplex signal.
The radio receiver according to the present invention has the advantage of enabling an appropriate reaction to different types of interference through the use of two auxiliary signals. It is thus possible, for example, to use the first auxiliary signal to allow a rapid and sensitive reaction to interference, even when transmitters are being received which do not send out a modulated subcarrier and, in particular, do not send out a stereo differential signal at the frequency of the subcarrier. The advantage of using the second auxiliary signal is that interference is only detected when it actually has an adverse effect on the audio signal.
Although in the case of the radio receiver according to the present invention it is also possible to process the auxiliary signals with a large range of values of, for example, 256 values, various specific embodiments are directed to a processing as binary signals, which can only assume the levels 0 and 1.
A first advantageous specific embodiment of the radio receiver according to the present invention consists in that the first and the second auxiliary signals are converted into binary signals, which are combined (gated) in a logic operation to form the interference signal. Besides allowing for a relatively simple further processing of the binary signals, this specific embodiment advantageously makes it possible to program a selection of the logic combination (AND operation or OR operation) or also to program an exclusive use of one of the auxiliary signals. Thus, for example, those radio receivers manufactured according to this specific embodiment, which are supplied to countries that do not have stereo-signal transmission, are programmed to only allow evaluation of the first auxiliary signal.
A second advantageous specific embodiment of the radio receiver according to the present invention is characterized in that the first and the second auxiliary signal are added, each after being weighted with a coefficient, and that, in dependence upon whether the resultant sum is larger or smaller than a threshold value, a binary interference signal is generated. This specific embodiment has the advantage over the first specific embodiment of allowing a wider range of possibilities for combining the two auxiliary signals.
A third advantageous specific embodiment of the radio receiver provides for a first control signal for attenuating the audio signals and a second control signal for reducing the channel separat
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Chahabadi Djahanyar
Herrmann Matthias
Kaesser Juergen
Vogt Lothar
Blaupunkt-Werke GmbH
Chang Vivian
Kuntz Curtis
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