Abstract: A volume control or amplitude varying system for digital signals includes a cascade connection of a coarse multiplier/divider for changing the values of digital signals in 6 db steps and a fine multiplier/divider for changing the values of digital values logarithmically in substantially equal steps of less than 6 db per step. The coarse multiplier/divider selectively multiplies the digital signal by powers of 2. The fine multiplier/divider multiplies the digital signal by predetermined values, an ascending/descending sequence of which form a substantially logarithmic sequence. Both serial-bit and parallel-bit embodiments are described.

Abstract: A sampled data filter used in a television automatic ghost cancellation system employs a single chain of cascaded delay elements and a crossbar switch matrix to implement the several different delayed sequences of samples that are used by the system to cancel several ghost signals. The rows of switch elements in the crossbar switch matrix are coupled to the individual delay elements, and the columns of the matrix are coupled to sample scaling circuitry. The scaled samples are summed to develop a psuedo-ghost signal which is combined with the input signal to cancel the ghost signal components.

Abstract: A scaling circuit for scaling PCM signals by factors less than one includes a bit-shift and truncating circuit. Roundoff error compensating circuitry adds an offset value to the samples to be scaled by the bit-shift circuitry to compensate for errors produced by truncation without rounding. The offset values are dithered to increase the apparent resolution of the system.

Abstract: Apparatus for multiplying a sampled data signal by a sinusoid having a period which is a multiple of the sample rate includes a plurality of sample scaling means to scale the sampled data signal by factors corresponding to the sine of angle .theta. over an angular range of 90 degrees in angular increments of 2.pi. divided by said multiple. A multiplexer multiplexes the scaled samples at the sample rate to produce a signal corresponding to the sampled data signal multiplied by the sinusoid. An embodiment is described for demodulating the stereo difference signal of a BTSC sound signal with serial-bit digital processing circuitry.

Abstract: A picture-in-picture image signal generator includes a source of an auxiliary video signal and an auxiliary synchronization component separator which produces an auxiliary odd/even field signal. Auxiliary image data is stored in a memory for subsequent retrieval. A source of a main video signal and associated synchronization component separator, which produces a main odd/even field signal, is also provided. A signal combiner combines a portion of the main video signal with data retrieved from the memory to form a picture-in-picture video signal. An interlace inversion detector generates a signal indicating an interlace inversion condition in response to the main and auxiliary odd/even field signals. A correction to the interlacing is made in response to the interlace inversion signal.

Abstract: A display processor using first and second chrominance map memories for storing values of first and second color-difference signals, each normalized respective to luminance signal. An image memory supplies, at pixel scan rate, data used to provide read-addresses to said first and second chrominance map memories and data used to describe the luminance signal. The first and second chrominance map memory read-outs are each multiplied by the luminance signal of appropriate spatial bandwidth to generate descriptions of the first and second color-difference signals i non-normalized form. These first and second color-difference signals and a full-spatial-bandwidth luminance signal are supplied to color matrixing circuitry. The color matrixing circuitry responds to these signals to provide red, green and blue drive signals to display apparatus. The display apparatus may comprise video amplifiers for the drive signals and a color kinescope, by way of example.

Abstract: An arrangement is provided for computing the magnitude value of the vector sum of two quadrature-related component signals I and Q with a minimal of hardware. To this end, the magnitude values of the orthogonal I and Q signals are applied to a ROM as address codes to produce the Log.sub.B .vertline.I.vertline. and Log.sub.B .vertline.Q.vertline. values to the logarithmic base B. The smaller of the Log.sub.B .vertline.I.vertline. and Log.sub.B .vertline.Q.vertline. logarithmic values is subtracted from the larger of the logarithmic values to produce the absolute value .vertline.D.vertline. of the difference between the respective logarithmic values. The difference value D is applied to a ROM as an address code which is programmed to generate a correction value F=0.5 Log.sub.B (1+B.sup.-2.vertline.D.vertline.).

Abstract: Apparatus for estimating noise in an electrical signal having substantially redundant recurring intervals includes circuitry for producing difference samples corresponding to signal differences between the recurring redundant intervals. A number of difference samples are averaged, and ones of the difference samples contributing to each average are subtracted from the averages. Magnitude values are extracted from the differences between the averages and the difference samples. A predetermined number of the magnitude values are averaged to produce a noise estimate signal.

Abstract: A frame comb type composite video decoder which does not require motion adaptive processing circuitry generates low frequency luminance signal components from one field of composite video signal. The high frequency luminance component is derived from two lines of composite video signal from each of two fields disposed before and after the field from which the low frequency luminance signals is developed.

Abstract: A binary subtracter stage for subtracting single bit binary numbers includes a first exclusive OR gate to which the numbers to be subtracted are applied. The output of the exclusive OR gate is connected to one input of a second exclusive OR gate which has a second input connected to a borrow input signal. The output of the second exclusive OR gate provides the difference between the single bit binary numbers. A borrow output signal is generated with the combination of a pass transistor coupled between the borrow input and borrow output terminals and a three state logic circuit which has its output termial connected to the borrow output terminal. The pass transistor is controlled by the output of the first exclusive OR gate and the three state logic circuit is controlled by the single bit binary numbers to be subtracted.

Abstract: In memory-based video signal processing systems such as frame recursive filters, for example, system performance is dependent upon critical timing relationships between incoming signals and delayed signals produced from the memory. Video signal from various sources, e.g. VTR's, tend to have jittering time bases that generally have prevented the use of such memory-based processing systems. The jittering signals may be standardized, in sampled data format, by effecting adaptive signal delays responsive to a measure of the relative phase of the sampling clock with respect to horizontal synchronizing pulses. The phase measure is used to control an interpolator which combines successive samples in proportions to develop sample values that should have occurred at the sample times had the signal not been jittering.

Abstract: A motion detector for determining image motion in a video signal develops an array of signals representing the difference between pixels from adjacent frames. The array of signals are grouped into subarrays, each of which include the signal corresponding to the pixel under examination for motion. Each of the subarrays are independently examined to determine if the magnitude of all of the pixel differences represented in a particular subarray exceed a predetermined threshold and/or the pixel differences have like polarity. If these conditions are met in any one of the subarrays, a motion signal is produced.

Abstract: A recursive filter for noise reducing composite video signal separately processes the luminance and chrominance components of the composite signal but requires only a single frame of storage. Input composite video signal is separated into luminance and chrominance component signals. The component signals are coupled to separate signal recursion scaling/combining circuits. The outputs from the recursion circuits are summed in an adder to produce noise-reduced composite video signal which is applied to a frame delay element. The output of the delay element is applied to a chroma/luma separator which separates the luminance and chrominance components and applies them to the respective recursion circuits.

Abstract: A video signal recursive filter includes circuitry for controlling the integration time of the filter. The control circuitry develop a motion-threshold value responsive to the noise content of signal differences developed by subtracting a processed signal, delayed by a frame period, from an incoming video signal. The signal differences are compared against the motion threshold to develop motion signals indicating the history of image motion for each picture element. Circuitry responsive to the signal noise content develops a signal which is coupled to the motion signals to form address codewords that are applied to a ROM programmed with predetermined control signals for establishing the integration time of the recursive filter.

Abstract: A motion detector for detecting interimage motion represented by composite video signals analyzes both the chrominance and luminance components for image motion. Interimage motion represented by the luminance component is determined from interimage signal differences. The interimage signal differences are separated into high and low frequency spectra corresponding to fine and coarse luminance image detail. Selected signal differences from the low frequency spectrum are summed and threshold detected to determine motion in the coarse image detail. The high frequency spectrum of the sample differences are applied to parallel summing circuits which sum different combinations of sample differences in order to discriminate motion signals from non-moving chrominance transitions. The detection signals from the high and low frequency motion detectors are combined to produce a luminance motion signal.

Abstract: A motion adaptive recursive filter is modified to separate luminance or chrominance signal from composite video. The filter proportions and sums current and frame delayed signal recursively to provide signal-to-noise enhanced luminance signal with the chrominance component reduced to a steady state residual value the first frame after motion ceases. Current composite video signal is appropriately scaled and combined with the signal-to-noise enhanced signal to cancel the residual chrominance component therein.

Abstract: A video signal processing system which employs a frame memory having a single output is operated to provide both field and frame delayed signals. The frame memory is operated in a serial mode at twice the video signal sample rate. Video samples are input to the memory on alternate stages and alternate samples output from the memory are routed back into the vacant memory stages. Alternate samples output from the frame memory correspond to field and frame delayed samples.

Abstract: A motion detector for detecting the occurrence of image changes between successive fields of video information includes a signal averager for averaging the video signal from two lines of video signal of one video field and a signal averager for averaging the video signal from three lines of video signal of a successive field. The two average video signals are coupled to comparing means which develops a motion indicating signal when the two average video signals differ.

Abstract: A recursive filter for effecting noise reduction of video signals, sums current and delayed signals and includes a motion detector for detecting interframe image motion. Signal from the motion detector is stored to provide a history of image motion. A decoder coupled to the motion detector and also responsive to the stored motion history develops control sequences for scaling the signal contributions which form the recursive filter sums.

Abstract: A field comb filter for separating luminance signal from NTSC composite video additively combines signals separated by 263 horizontal lines. Vertical detail is restored and motion compensation provided by subtractively combining signal separated by 262 horizontal lines and adding the difference to the separated luminance signal.