Abstract: A system is provided for filtering and demodulating digital color mixture signals, wherein the signals are filtered to remove out-of-band noise prior to completion of the demodulation process. Interleaved digital chrominance signal samples are first demodulated by a signal related in frequency to the video subcarrier to obtain interleaved color mixture signal samples of different sampling phases at baseband frequencies. The interleaved color mixture signal samples are applied to a digital filter at a rate which is a multiple of the color subcarrier frequency. The weighting coefficients of the filter are selected to obtain a bandwidth which passes the color mixture signal while removing out of band noise. Since the input signal sequence to the digital filter contains interleaved color mixture signal samples, alternate stages of the filter shift register are tapped, so that the output sequence will comprise filtered and interleaved color mixture signal samples.

Abstract: A sampled data filter for separating chrominance signal from digitized composite video sampled at a 4f.sub.sc rate produces filtered sampled data chrominance signal at one half the input sample rate. The input video signal occurring as a 4f.sub.sc +I, +Q, -I, -Q sample sequence is decimated in the filter so that only the filtered replicas of the +I and +Q samples are computed. This effectively doubles the computational time permitted the filter circuitry without substantially compromising signal content.

Abstract: A frame-to-frame comb filter for separating chrominance and luminance signals from composite video signals produces objectionable double images around the edges of moving objects. The double images are substantially removed by low pass filtering the combed chrominance signal and combining the low pass filtered chrominamce signal with the combed luminance signal.

Abstract: Frame-to-frame comb filter for separating chrominance and luminance components of composite video signals produce distortions around the periphery of reproduced moving images. The color distortions are corrected by selectively adding the combed luminance signal to the combed chrominance signal during periods of detected motion, and bandpass filtering the combined signal to pass only the chrominance spectrum.

Abstract: A system for controlling the speed of a brushless DC motor includes a microprocessor for generating stator control drive signals responsive to Hall sensors detecting relative rotor-pole-stator positions. Hall sensor signal transistions are compared against a reference frequency to provide an error signal which is processed by the microprocessor in accordance with a transfer function to emulate a type II servo loop. Stator commutation control signals are reduced in duration proportional to the resulting processed error signal. The control signals are thereafter applied to integrating current drives energizing the stator coils with triangular current signals.

Abstract: A method is described for generating continuously variable sets of weighting coefficients for application to weighting circuits of a sampled data filter. The generated coefficients are produced by scaling the time axis of the impulse response described by a set of standard or nominal weighting coefficients in an inverse manner to a desired scaling of the filter frequency response. The coefficient values at the scaled time points are calculated by a piecewise linear interpolation process and correspond to the scaled coefficients. By this technique, a large number of sets of weighting coefficients may be generated from a single set of coefficients with relatively few circuit elements.

Abstract: A circuit for incrementing or decrementing a binary number is described. An M bit binary number is applied to M dynamic latch circuits. The latch output signals are applied to M logic units each comprising an exclusive OR, an exclusive NOR and one transistor. The transistors of the respective logic units are connected serially, with the transistor of the logic unit operating on the LSB of the binary number being further connected to a carry in or count signal. The exclusive OR is responsive to the carry in signal and the latched signal to increment/decrement or pass through the respective bit of the binary number. The exclusive NOR is responsive to an Up/Down signal and the latched signal for controlling the conduction state of the respective transistor thereby providing a carry in signal to the input of the next adjacent logic unit operating on the next more significant bit of the binary number.

Abstract: A velocity correction apparatus for a disc record player includes a permanent magnet attached to a cartridge mounted pickup arm and an electromagnetic coil secured in a cartridge supporting carriage. The coil is fixed to a supporting member which conformally engages structural features of the cartridge to guarantee proper alignment of coil and magnet. The coil support is mounted to permit limited rotation thereof to facilitate installation of the cartridge in the carriage and is mechanically biased to maintain coil-cartridge engagement and to maintain the cartridge in its normally operative position in the carriage.

Abstract: Circuitry included in a TV receiver for enhancing the signal-to-noise ratio of the chrominance signal includes an adaptive linear phase, low pass filter which has its bandwidth controlled responsive to the upper frequency components of the current chrominance signal. A frequency analyzer coupled to the chrominance channel counts the number of chrominance signal excursions during predetermined periods to generate a number related to the maximum signal frequency during such periods. The number is applied to a decoder which generates address codes for application to a look up table which provides filter coefficients for altering the filter bandwidth in accordance with the current maximum signal frequency components.

Abstract: A signal separation system is provided which includes a plurality of serially-coupled signal transfer stages. A video information signal is applied to an input stage and is delayed by at least the time interval of one horizontal television line (1-H) as it passes through the stages. Various ones of the stages which are 1-H apart in time include outputs, which are combined by weighting function and summing or difference circuits to produce bandwidth-limited transversal filter output signals. These signals are additively and subtractively combined to produce a combed band passed chrominance signal and a fully restored and combed luminance signal, thereby obviating the need for subsequent filtering before the signals are further processed. The bandwidth-limited signals may also be combined to provide a user adjustable peaking control signal for the luminance information channel.

Abstract: A variable gain control system for a digital signal is provided in which the digital signal addresses a digital memory to produce an output signal representative of the addressing signal modified by a transfer characteristic. A control word M is repetitively loaded into an M counter, which counts to a predetermined limit to produce output pulses when the limit is reached. The output pulses increment a data counter. Concurrently, an N control word is repetitively loaded into an N counter, which also counts to a predetermined limit to produce output pulses when that limit is reached. The output pulses of the N counter increment an address counter. When the count of the address counter changes, the current value of the data counter is loaded into a digital memory at the address provided by the address counter. The memory is loaded in this manner to store a data array representative of a signal gain related to the ratio of the N to M.

Abstract: A comb filter arrangement operating at a reduced data rate is provided, which requires comparably fewer storage locations than previous arrangements. A digitized composite video signal of a given codeword rate is applied to a first bandpass filter, which produces a filtered signal restricted to a portion of the passband of the composite video signal. The filtered signal is then subsampled at a rate which satisfies the Nyquist criterion for information of the restricted passband. Codewords, now at a reduced data rate, are applied to a one-H delay line, and delayed and undelayed signals are combined to produce a first comb-filtered signal. The first comb-filtered signal is then applied to a second bandpass filter, which provides a sequence of codewords at the codeword rate of the original digitized composite video signal over a given frequency band. This sequence of codewords is then combined with the codewords of the composite video signal to produce a second comb-filtered signal.

Abstract: A signal substitution system is employed in audio processing circuitry to compensate for impulse noise and signal dropouts. Stored or delayed audio signal is substituted in the IF portion of the receiver circuitry ahead of the IF filters thereby precluding the noise impulses from exciting the filters into a ringing mode and significantly broadening what are otherwise very narrow signal disturbances. To insure that the substitution signal is in relative phase coherence with the substituted signal, the substitution signal is delayed an integral number, N, of cycles of the audio carrier. The number N is chosen to be small, resulting in the change in the modulating signal corresponding to the stored portion of the carrier being small. The affect on the baseband signal is that during instances where defects occurred the signal appears to have been sampled and held, but the duration is so short that they are not audibly distinguishable.

Abstract: Imbalances in the potential appearing across the drain electrodes of source coupled FET transistors arranged in a differential amplifier configuration tends to produce input offset voltages. Where the drain electrodes of the transistors are coupled to a current mirror load for converting balanced signals to a single ended output which in turn is applied to a common source amplifier, the input offset may be nulled by differentially adjusting the drain current of the common source amplifier against the source current of the differential stage.

Abstract: A signal pickup cartridge is formed in two sections to facilitate assembly of a leaf spring to a stylus therein. The two sections are dimensioned to permit suspension of the stylus to the first section but protruding therefrom and connection of one end of the leaf spring to the second section with the second end of the leaf spring also protruding therefrom. The leaf spring is connected to the stylus after which the two cartridge sections are joined to form a contiguous enclosure to house the stylus assembly.

Abstract: A two phase waveform generator for producing nonoverlapping pulses is designed with a CMOS inverter modified to include a resistor between the drain electrodes of the complementary inverter transistors and three conventional CMOS inverter circuits. The resistor n-type transistor interconnection exhibits a fast negative signal transition but a slower positive transition due to the resistor. This effect tends to shorten the duration of pulses applied to the inverter input. The shortened pulses are applied to a cascade connected pair of inverters to sharpen the waveform and produce a first phase output signal. The resistor-p-type transistor interconnection of the modified inverter exhibits a fast positive signal transition but a slower negative transition. This effect tends to widen pulses applied to the input. The widened pulses are applied to another inverter which complements the widened pulses ultimately generating narrower pulses which comprise a second phase signal.

Abstract: Comb filter arrangements are provided for separating frequency interleaved signal components of a video signal. A video signal is sampled at a rate which satisfies the Nyquist criterion for the bandwidth of the signal, and the resultant signal samples are applied to a bandpass filter. The bandpass filter produces a filtered signal restricted to a portion of the original video band. The filtered signal is subsampled at a rate which satisfies the Nyquist criterion for the information of the restricted passband, producing replicas of the restricted passband beginning approximately at zero Hertz and extending upward in frequency about frequencies which are multiples of the subsampling frequency and its harmonics. The subsampled information in the replicated passbands is comb filtered, and the comb filtered signals are interpolated up to the original sampling rate of the video signal.

Abstract: A system for recording and recovering analog signal in digital format utilizes a substantially video field format without the vertical blanking intervals thereby eliminating the need to time compress the information on a field by field basis. The digital signal is encoded for error correction of burst errors at least one line in length. Auxiliary digital information is substituted for particular lines of encoded signal for purposes of identifying the position of the playback transducer. The recovered signal is decoded by an error correcting decoder which recognizes the auxiliary information as a signal burst error and reconstructs the signal that was substituted by the auxiliary information. The decoded signal is then converted to a time continuous analog signal.

Abstract: A simplified drive circuit for applying bipolar drive current to a stepper motor includes a switch for alternately connecting a first end of the stator winding between supply potential and ground. The second end of the winding is coupled to supply potential by a resistor and coupled to ground by the parallel combination of a second resistor and a capacitor. The capacitor alternately operates as a short circuit when supply potential is applied to the first end of the winding and as a battery when the first end of the winding is grounded.

Abstract: A flash type A/D converter has a plurality of transistor switch means for alternately connecting respective ones of a plurality of reference potentials or input signal to a plurality of summing capacitors each serially connected to a self biased inverter (comparator) circuit. Certain ones of the switches are configured to operate in the source follower mode to preclude excessive capacitor discharging when extremes of input signal are applied. This reduces the current required to recharge the capacitors by the reference potential source and tends to limit loading affects on the reference source. In addition certain ones of the switch transistors have their turn on or threshold potentials tailored to effectively reduce feedthrough between the respective switch control electrodes and the capacitor-switch interconnection.