Abstract: System and method for an all-digital audio receiver for a BTSC MTS audio signal or other composite signal that is FM modulated. A preferred embodiment comprises a digital FM demodulator for receiving an analog to digital quantized SIF signal and performing demodulation and outputting a composite audio signal, and a digital audio processor for decomposing the composite audio signal into at least the SAP, stereo and monaural signals for audio reproduction. In a preferred embodiment, the digital audio processor is a programmable digital signal processor. In a preferred embodiment, the digital FM demodulator and the digital audio processor are implemented as an integrated circuit. Methods for processing the audio signal using the digital processors of the invention are provided.

Abstract: A SECAM decoder and an FM modulator therefor are disclosed, in which a demodulated color signal is provided to indicate deviations in the frequency of modulated color information from a nominal subcarrier frequency. The demodulator comprises numerator and denominator filters operating on the modulated color information, and a divider providing a ratio result by dividing the numerator filter output by the denominator filter output. The demodulator may include two sets of numerator and denominator filters offset in phase from one another, where one of the two sets is selectively employed in order to mitigate divide-by-zero problems. Also disclosed are methods for demodulating digitized FM color signals in a SECAM decoder.

Abstract: A phase-locked loop is provided which is operable to lock the sampling clock (pixel clock) to the incoming horizontal sync pulse contained within composite video information. Given the input signal is a VCR signal or a normal noise-free signal, there exists two modes of operation, coarse lock mode and fine lock mode, which are used in controlling the phase-locked loop. In the coarse lock mode, coarse corrections are made to a horizontal discrete time oscillator so that a fast lock may be achieve using the fine lock mode. Coarse corrections are based on a normalized sum of weighted pixels collected within a narrow gate window. Lock is achieved when the falling edge is centered within the window. Given the input signal is a television signal having noise, there exists one mode of operation where the flat window phase detector is used instead of coarse lock mode to bring the sync edge to fall within the window, where the flat window normalization constant is tuned.

Abstract: The present invention discloses a horizontal sync detector circuit (10) comprising a filter portion (12), an equilibrium accumulator portion (14) coupled to the filter portion (12), a horizontal sync detector portion (16) coupled to the filter portion (12) and to the equilibrium accumulator portion (14), and an output logic portion (18) coupled to the horizontal sync detector portion (16), the output logic portion (18) adapted to produce a phase error (116) based on a combination of a coarse phase error (108) and a fine phase error (112).

Abstract: The present invention discloses a PLL (90), which may be implemented in software, hardware, or a combination of software and hardware, which comprises a sync detector (92), a loop filter (94), a vertical sync discrete time oscillator (DTO) (98), and an output logic (100) adapted to detect a vertical sync (222), wherein the loop filter (94), the vertical sync DTO (98), and the output logic (100) are coupled to the sync detector (92).

Abstract: The present invention discloses a PLL (90), which may be implemented in software, hardware, or a combination of software and hardware, which comprises a sync detector (92) adapted to output a phase error (152), a vertical sync discrete time oscillator (DTO) block (98) adapted to output a vertical sync DTO (130) based on the phase error (152), and an output logic (100) adapted to detect a vertical sync based on the vertical sync DTO (130).

Abstract: A phase-locked loop is provided which is operable to lock the sampling clock (pixel clock) to the incoming horizontal sync pulse contained within composite video information. Given the input signal is a VCR signal or a normal noise-free signal, there exists two modes of operation, coarse lock mode and fine lock mode, which are used in controlling the phase-locked loop. In the coarse lock mode, coarse corrections are made to a horizontal discrete time oscillator so that a fast lock may be achieve using the fine lock mode. Coarse corrections are based on a normalized sum of weighted pixels collected within a narrow gate window. Lock is achieved when the falling edge is centered within the window. Given the input signal is a television signal having noise, there exists one mode of operation where the flat window phase detector is used instead of coarse lock mode to bring the sync edge to fall within the window, where the flat window normalization constant is tuned.

Abstract: A SECAM decoder and an FM modulator therefor are disclosed, in which a demodulated color signal is provided to indicate deviations in the frequency of modulated color information from a nominal subcarrier frequency. The demodulator comprises numerator and denominator filters operating on the modulated color information, and a divider providing a ratio result by dividing the numerator filter output by the denominator filter output. The demodulator may include two sets of numerator and denominator filters offset in phase from one another, where one of the two sets is selectively employed in order to mitigate divide-by-zero problems. Also disclosed are methods for demodulating digitized FM color signals in a SECAM decoder.

Abstract: A color comb filter (46), video decoder (40) and method for separating chroma (U,V) and luma (Y) signals from a composite video signal (41). The comb filter (46) includes circuitry (48) for generating color filter selections for filtering a chroma video signal (41) and control logic (62) for determining the filter selections based on color boundary properties of the chroma video signal (U,V). The video decoder (40) includes a comb filter (46), a demodulator (42), low pass filter (44), a remodulator (48) and a subtractor (50). The filtered, remodulated chroma signal (Uout,Vout) is subtracted from the composite video signal (41) to produce a luma signal absent hanging dots and false colors.

Abstract: A system for the digital decoding of composite video signals (CVBS), comprising a brightness signal (luminance component Y) and two color difference signals (chrominance components U, V). The system modulates a color subcarrier according to the quadrature amplitude modulation principle, in which a plurality (N) of sample values of the video signal are transformed by a Walsh-Hadamard transformation (WHT) from the pixel domain into the WHT domain. The color difference signals (U, V) are derived as specific WHT coefficients of the WHT matrix obtained. The WHT coefficients determining the color difference signals (U, V) are subtracted from the WHT matrix. The WHT matrix is transformed back into the pixel domain an inverse Walsh-Hadamard transformation (IWHT), and the brightness signal (Y) are derived from the IWHT result.

Abstract: The invention relates to a digital multistandard decoder for composite video signals. The multistandard decoder according to the invention can selectively process NTSC or PAL video signals and there is no need to know the corresponding signal standard beforehand.

Abstract: The invention is a sample rate converter, which converts input sample values of a signal digitized with a first predetermined clock frequency into desired sample values at a second virtual sample frequency, with a delay device, which delays the serial input sample values and outputs in parallel a block of delayed input sample values z.sup.-2 to z.sup.+2, a computing device, with a WHT stage, which transforms the delayed input sample values (z.sup.-2 to z.sup.+2), by using a Walsh-Hadamard transformation, into the WHT domain, and an interpolating device, which interpolates in equally weighted manner the resulting WHT coefficients and performs an amplitude correction of the interpolation results.

Abstract: A frequency-modulated input signal is converted at an adequately high sampling rate into a time-discrete and amplitude-discrete digital signal. This digital signal is applied to a simple transversal filter, having a sloping amplitude characteristic, more specifically having a sin.sup.2 transfer function and a constant group delay time, and to a delay device having a time delay which is equal to the group delay time. The output signal of the filter is applied to a numerator input of a divider (6) and the output signal of the delay device to a denominator input the divider (6) whose quotient contains the frequency corresponding to the amplitude characteristic of the filter. In this manner, a frequency demodulator having a very good AM-suppression and an adequate linearity at broad-band-FM is realized. The divider is formed, in accordance with the "pipeline principle", from a plurality of identically constructed sections corresponding to the number of bit positions of the processed digital signals.

Abstract: A charging current source and a discharging current source are alternately connected to an input capacitor. By choosing the current ratios it is possible to switch a reference level located in the signal range, for example the black level in a television signal, in the circuit, without the necessity for interval keying.