Television – Image signal processing circuitry specific to television – Chrominance signal demodulator
Reexamination Certificate
2007-11-20
2007-11-20
Kostak, Victor R. (Department: 2622)
Television
Image signal processing circuitry specific to television
Chrominance signal demodulator
C348S727000, C329S343000
Reexamination Certificate
active
10998386
ABSTRACT:
A time-based, digital FM demodulator circuit receives a stream of digital samples corresponding to an analog FM waveform. The samples are provided to a zero crossing detector, which allows a counter to determine a number of clock cycles between zero crossings. The resolution of this coarse period determination is further refined by an intercept calculation, which further localizes the zero crossing of the FM waveform based on interpolation between samples on either side of the zero crossing. Accuracy of the period determination may be further enhanced by use of a sinusoidal correction filter, which minimizes error caused by the linear interpolation performed on the sinusoidal waveform. Although the FM demodulator circuit is particularly suitable for demodulation of the chroma component of a SECAM video signal, it may advantageously be applied in a wide variety of FM demodulation applications.
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Cirrus Logic Inc.
Kostak Victor R.
Wong Cabello Lutsch Rutherford & Brucculeri LLP
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