Radio receiver with masking of switchover noise
AssigneeBlaupunkt-Werke GmbH
InventorsPeter Erben, Helmut Liman, Wilhelm Hegeler, Harald Bochmann, Jurgen Kasser, Werner Henze
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Abstract
The Radio Data System (RDS) protocol promulgated by the European Broadcasting Union provides for alternate frequencies (AF) for the same broadcast. Receivers periodically switch over to such an alternate frequency, leading to momentary crackling noises. In a radio receiver having a device for temporary switchover from a received frequency to some other frequency, substitute signals are inserted into the audio signals that are interrupted during the temporary switchover. The substitute signals are formed from the audio signals before and optionally also after the temporary switchover.
Claims14
In a radio receiver having
- storing means (9;
- 41, 42) for continuously storing a most-recently-received portion of a radio transmission;
- and
- switchover means (1, 5, 34) for automatic switchover from a first reception frequency to a second reception frequency,
- a method of suppressing audio output of noise during a switchover from a first reception frequency to a second reception frequency, comprising the steps of:
- continuously storing said most-recently-received transmission portion;
- upon cessation of audio signals received at said first reception frequency, retrieving, from said storing means (9;
- 41, 42), said most-recently-received transmission portion and directing audio output thereof as a substitute signal;
- repeating audio output of said most-recently-received transmission portion until audio signals are received at said second reception frequency;
- and
- performing a dissolve or temporary averaging between said most-recently-received transmission portion and said audio signals received at said second reception frequency, during transition therebetween, thereby minimizing jumps in amplitude and phase of a resulting audio output signal.
A radio receiver having
- a tuner (31);
- a stereo decoder (37) connected to an output of said tuner (31);
- a pair of analog-to-digital converters (38, 39), each having an input connected to said stereo decoder (37), and an output furnishing a digital channel signal;
- a microprocessor (34) having a control output (33) which controls said tuner (31) and including means for automatic switchover from a first reception frequency to a second reception frequency;
- audio processing means (40), coupled to said outputs of said pair of analog-to-digital converters (38, 39), for producing audio output signals and switching between a stereo reception mode and a monaural repetition mode:
- storing means (54, 55), coupled to an output (R, 42, 51) of said audio processing means (40), for continuously storing a most-recently-received .portion of a radio transmission for subsequent use in generation of substitute output signals;
- a digital-to-analog converting output stage (45-50);
- and
- switch means (43, 44), coupled to selectively receive said audio output signals or substitute output signals from said storing means, and responsive to signals from said microprocessor (34) directing automatic switchover from one reception frequency to another, for suppressing audio output of noise during said switchover by feeding said substitute output signals (SE) to said output stage (45, 46) instead of audio output signals from said audio processing means (40).
Dependencies are inferred from the claim text.