Digital stereo recovery circuitry and method for radio receivers
AssigneeCirrus Logic, Inc.
InventorBrian D. Green
Life of this patent
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Abstract
Stereo recovery circuitry for a digital receiver is disclosed that provides increased accuracy and efficiency in recovering stereo signal information from transmitted stereo signals. The stereo decoder includes a digitally controlled oscillator that recovers a pilot tone signal from transmitted stereo signal information. By processing demodulated stereo signals on the digital side and digitally controlling the oscillator, the stereo decoder has increased efficiency and accuracy. In one embodiment, the oscillator may be a phase-locked-loop having a loop filter and an amplitude stabilized tunable resonator. Additional circuitry is disclosed for utilizing the pilot tone signal to recover left and right channel signal information from the demodulated stereo signals.
Claims17
A radio receiver system for processing stereo signal information transmitted by radio stations, comprising:
- an antenna;
- a frequency converter coupled to receive signals from the antenna, the signals including stereo signal information;
- a digital receiver coupled to receive signals from the frequency converter;
- and
- stereo recovery circuitry within the digital receiver including a digitally controlled oscillator having a digital phase-locked-loop and a pilot tone signal as an output signal, the pilot tone signal being recovered from the stereo signal information, wherein the digital phase-locked-loop comprises a loop filter coupled to a tunable resonator, the tunable resonator having the pilot tone signal as the output signal.
Stereo recovery circuitry for a digital receiver, comprising:
- an input signal including stereo signal information;
- and
- a digitally controlled oscillator comprising a digital phase-locked-loop and having a pilot tone signal as an output, wherein the pilot tone signal is recovered from the stereo signal information and wherein the digital phase-locked-loop comprises a loop filter coupled to a tunable resonator, the tunable resonator having the pilot tone signal as the output.
A method for decoding stereo signal information, comprising:
- receiving signals including stereo signal information;
- utilizing a digitally controlled oscillator to recover a pilot tone signal from the stereo signal information wherein the digitally controlled oscillator is a digital-phase-locked-loop including a loop filter and a digitally controlled tunable resonator, the tunable resonator having the pilot tone signal as the output;
- and
- wherein said oscillator is digitally controlling an amplitude for the tunable resonator.
Dependencies are inferred from the claim text.