Abstract: A digital FIR filter is provided that inputs a series of data samples x[0] . . . x[n] and generates a partial sum output PS[i], where i≦n. The partial sum output is a weighted version of the a difference between a partial sum of the previous i−1 data samples, PS[i−1], and the current data sample x[n] added to the current data sample x[n]. The filter includes a plurality of weighting stages. Each weighting stage includes a first adder for subtracting the current data sample x[n] from the previous partial sum PS[i−1], a multiplier that multiplies the difference by a weighting coefficient, and a second adder that sums the weighted difference with the current data sample. The filter also includes a plurality of delay elements, each of which inputs a partial sum and imposes a unit delay on the partial sum before supplying it to a weighting stage.

Abstract: A signal processing system and process for digitally filtering a single tone digital signal is disclosed. The system includes a single tone signal generator, which may or may not perform frequency modulation. The single tone signal generator receives an input signal and generates a frequency indicator which is used internally by the single tone signal generator and is also communicated to a direct realization filter. The direct realization filter uses the frequency indicator to generate a phase offset indicator, which is communicated back to the single tone signal generator. The single tone signal generator uses the frequency indicator and the phase offset indicator to generate a phase-adjusted single tone signal. The direct realization filter generates a filter gain and multiplies the single tone signal with the filter gain to produce a filtered single tone signal.

Abstract: An apparatus and method for converting pixel data from a computer video format to a television-compatible composite video waveform. A color space converter converts RGB or YCrCb pixel data into YUV pixel data. The YUV pixel data is supplied to an encoder which encodes the data into a composite video waveform. A clock generator generates an encoder clock frequency based on the horizontal resolution of the incoming computer pixel data. The encoder clock frequency is sufficient to allow encoding of all incoming pixels in the active video portion of the waveform without physically scaling or altering the pixel data. Sync and burst processors in the encoder encode sync pulses and burst waveforms at proper timing intervals despite the variable encoder clock frequency by accessing sync pulse and burst waveform values and timing parameters appropriate to ranges of clock frequencies that are stored in a ROM.

Abstract: An adaptive signal separation system and method for quadrature amplitude modulated signals that is particularly well-suited for YC separation of a composite television signal. An adaptive approach for separating overlapping signals wherein the adaptive approach selects between notch or equivalent filtering and a comb filtering system, wherein the chrominance is first demodulated to the IQ domain prior to comb filtering. The demodulated comb filtered IQ data streams are then re-modulated to reconstruct the luminance portion of the signal.

Abstract: An adaptive method and system for processing luma and chroma signals from lines of a video signal. The invention includes an adaptive comb filtering algorithm that determines whether to average lines of video data based on the signal content. If two lines are dissimilar, a simple notch/bandpass system is used. The invention provides improved adaptive comb filtering performance at vertical transitions between high-luminance-detail areas and between other areas such as solid colors or flat gray or white fields by dynamically determining whether to average the chrominance information of the current video line with the chrominance information of the previous line, next line, both of such lines, or neither of such lines.

Abstract: Successive pixels representing video data in successive lines in a raster scan are buffered. Each of the lines has a sync pulse defining the line beginning. A phase adjustment is determined between the sync pulse, preferably at a particular level in the sync pulse, and an adjacent one of system adjacent clock signals at a particular frequency. The actual or expected phase adjustment between the pixels at the end of each line is also determined. The difference between the phase adjustments at the beginning and end of each line is then determined. Progressive adjustments are made in the phase of each successive pixel in the line relative to the system clock signals in accordance with the number of system clock signals in the line and the determined difference in the phase adjustment between the line beginning and end. In this way, the pixels of video data are synchronized with the system clock signals.

Abstract: Successive pixels representing video data in successive lines in a raster scan are buffered. Each of the lines has a sync pulse defining the line beginning. A phase adjustment is determined between the sync pulse, preferably at a particular level in the sync pulse, and an adjacent one of system adjacent clock signals at a particular frequency. The actual or expected phase adjustment between the pixels at the end of each line is also determined. The difference between the phase adjustments at the beginning and end of each line is then determined. Progressive adjustments are made in the phase of each successive pixel in the line relative to the system clock signals in accordance with the number of system clock signals in the line and the determined difference in the phase adjustment between the line beginning and end. In this way, the pixels of video data are synchronized with the system clock signals.