Abstract: A video disc player includes a phase locked loop (PLL) heterodyne converter for providing frequency translation and time base correction of the chrominance component of a composite video signal recovered when a disc is played. Residual time base errors due to the finite loop gain of the PLL are minimized by means of a phase modulator controlled by the PLL error signal. In one illustrative embodiment, the phase modulator is coupled so as to vary the phase of the translated chrominance output signal. In another embodiment, it is coupled to vary the phase of a demodulation carrier wave supplied to a chroma demodulator whereby, in either case, chroma streaking effects due to finite gain limitations of the PLL are minimized with no increase in loop gain thereby avoiding potential loop instabilities.

Abstract: A video disc player includes a pick-up cartridge in which the stylus is supported by a stylus holder that is mechanically resonant at a frequency within an audio frequency range. A pick-up converter coupled to the stylus provides a broad audio video output signal that is undesirably modulated due to the stylus holder mechanical resonance. The audio signal is demodulated to baseband and linearly combined with the un-demodulated broadband signal to provide a resultant audio output signal in which audio frequency noise components, due to the mechanical resonance of the resulus holder, are attenuated.

Abstract: A television receiver is adapted for use of standardized plug-in descramblers which are coupled to the receiver by a connector. The connector is accessible from the exterior of the housing of the receiver without significant disassembly. The connector has terminals electrically coupled to various key points in the receiver. Each type of descrambler is adapted for descrambling a particular type of scrambled signal, and for that purpose uses certain of the connector terminals. The plug-in descrambler also selects the operating frequency characteristics of the tuner.

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 transitions are compared against a reference frequency to provide an error signal which is processed by the microprocessor. Stator commutation control signals are provided dependent upon the Hall sensor signal transitions. A control signal along with the commutation control signals are thereafter applied to integrating current drivers which provide substantially rectangular current pulses to the stator coils.

Abstract: A pair of voltage followers, having offsets which differ by a fraction of the threshold voltage of a diode, are coupled to respective sources of signal and load voltage to provide unequally offset ouput voltages. An amplifier, coupled to the voltage followers, provides an output current when the difference of the signal and load voltages is of a given sense and magnitude, the output current being substantially zero otherwise.

Abstract: Digital audio data to be recorded in a pseudo-video format on a disc record is applied to an error check encoder that encodes each line of data with an error check code. The encoder is preset to an initial state corresponding to a recording track number prior to encoding each data line. The track number is changed periodically during recording whereby track information is conveyed by the form of the error check code without requiring additional bits of information in the data lines. Upon playback of the disc, the encoded data is applied to an error check decoder that is preset to an initial state corresponding to an expected track number. Upon decoding, errors in the recovered data are corrected and the recorded track number is recovered. The expected and recovered track numbers are compared to provide a track error correction signal whereby tracking errors may be corrected on a line-by-line basis within each pseudo-video field without need for additional bits in the recorded data.

Abstract: Dual squelch circuits, the first preceding and the second following the video processor of a video disc player, are selectively activated by a control unit which receives transducer position information from the processor for calculation of disc playing time and control of the signal recovery transducer. The first squelch circuit aids in stabilizing the timebase correction servo of the video processor during the player pause operating mode. The second squelch circuit maintains video blanking during certain player transition operating modes (e.g., pause-to-play, load, etc.) while the control unit processes the position information to provide transducer control and playing time indicator signals.

Abstract: Direct current isolation and A.C. power line voltage reduction are provided in a first D.C. power supply by means of transformer coupling and in a second D.C. power supply by means of capacitor coupling which, additionally, provides suppression of differential mode and common mode components of high frequency noise or RF signals which may be present on the A.C. power line. The primary winding in the transformer coupled supply is switched and the D.C. output voltages produced by the supplies are combined to form a resultant bias signal of a first polarity and having relatively high current capability when the switch is closed, the bias signal being of a second polarity and having relatively limited current capability when the switch is open whereby high A.C. to D.C. conversion efficiency is achieved for either condition of the power switch.

Abstract: A filter limits the bandwidth of a caption video signal in a video disc player to minimize color beats when the caption signal is displayed along with a picture video signal on a television receiver. The filter delay, which would otherwise cause offset between the caption and an associated background signal used to enhance visibility of the caption, is compensated for by extending the time duration of each occurrence of the background signal by a multiple of the filter delay.

Abstract: A surface acoustic wave recording device is constructed for use in recording video signals in the surface of a master substrate. The device includes a pyramidal-shaped tip having a plurality of transducer electrodes for launching surface acoustic waves on the surfaces of the device structure. Surface acoustic waves launched from the plurality of transducers are focused at the apex of the record device. A stylus, for example, of diamond, affixed to the apex of the pyramidal structure vibrates in consonance with the signal to be recorded to cut the video signals into the surface of the master substrate.

Abstract: The deviation of an FM signal modulated by a video signal is detected by measuring the average period of the FM signal at a measurement rate proportional to the average frequency of the FM signal. The value of each average period measurement is compared with a predetermined number to produce an indicator signal each time the measured value is less than or equal to the predetermined number. The effect of overshoot of the video signal due to preemphasis is minimized by detecting the successive occurrence of at least two indicator signals to provide a further indicator signal which may be used for visually monitoring video peak levels and/or for protecting a utilization device to which the FM signal is supplied.

Abstract: The DC component of an input signal is regulated at a constant amplitude to provide a resultant signal that is coupled to an output node via variable transmission means to provide a processed output signal. Feedback control means, coupled to the variable transmission means, regulates the DC component of the processed output signal linearly in accordance with the amplitude of a gain control signal thereby providing corresponding linear changes in the amplitude of the AC component of the processed output signal without need for linear transmission elements in the variable transmission means.

Abstract: A resistance-capacitance filter smoothes the control voltage of an audio signal expander. An analog gate couples the greater, in a given sense, of the smoothed control voltage and a further voltage to the control terminal of a variable gain device in the audio signal path, the further voltage being equal to the filter input voltage less a constant equal to Vbe. A time constant modifier circuit reduces the filter time constant when the filter input voltage differs in either sense from the smoothed control voltage by a fraction, less than unity, of Vbe. The resultant, relatively "narrow" dead zones of the adaptive filter enable operation of the expander with relatively low signal voltage levels thereby enabling a corresponding reduction in supply voltage requirements and providing further advantages such as reduced power dissipation, reduced heat build-up and improved reliability.

Abstract: In a record playback system, such as a video disc player, there is tendency to radiate energy at a given frequency from the vicinity of the stylus where the stylus passes through the carriage bottom during playback. A first radial transmission waveguide path is provided in association with the carriage bottom. A second radial transmission waveguide path is provided between the carriage bottom and the record. The first and second paths are made to differ from one another by 180 electrical degrees. There is thus a reduction in radiated energy at the given frequency in the radial location which forms the common end of the first and second paths by signal cancellation at this common location.

Abstract: In a record playback system, which includes a carriage within which a stylus arm is mounted, it is desired to clean the stylus tip from time to time. The apparatus according to the present invention lowers and lifts the stylus so as to effect stylus-record engagement and disengagement and in addition the same apparatus cleans the stylus tip during the lowering-lifting cycle.

Abstract: RF switching diodes in the antenna transfer switch of a video disc player are reverse biased by means of a bias supply when the main power supply of the player is turned off. The reverse bias counteracts any tendency for RF signals applied to the player antenna input connector from forward biasing the diodes which otherwise could result in intermodulation distortion of antenna input signals coupled to the player RF output connector. The effect of the reverse bias is augmented by a high pass filter in the antenna transfer switch which attenuates RF input signals at frequencies below the lowest assigned television channel frequency.

Abstract: A signal to be delayed is applied to a frequency selective path including an inverting active bandpass filter and to a non-frequency selective path including a voltage-to-current converter. The paths are coupled to a signal combiner which produces an output current having a first component proportional to the output current of the converter and a second component directly proportional to the filter output voltage and inversely proportional to the value of a gain control resistor. The resistor is selected to provide a predetermined ratio of the output current components to provide an overall allpass characteristic for the delay circuit and biased to conduct no current under quiescent signal conditions thereby reducing power dissipation. Several circuits may be cascaded for such purposes as peaking and delay equalization in television receivers, video disc players or the like.

Abstract: A composite video signal including a timing component and a caption video signal having no timing component are combined to form a resultant video signal for application to a television receiver. The caption signal is produced by a character generator that is normally synchronized with the timing component of the composite video signal. A substitute timing signal is supplied to the character generator and also added to the player output signal under conditions which interrupt the timing component of the composite video signal whereby captions may be continuously displayed on the television receiver notwithstanding partial or total interruption of the composite video signal.

Abstract: A signal source continuously produces a horizontal timing signal proportional to the line rate of a recovered composite video signal. A vertical timing unit coupled to the source continuously produces a vertical timing signal proportional to the field rate of the video signal. An error detector processes data words present in the vertical interval of the composite video signal to provide a data status signal indicative of the validity of each processed data word. The data status signal is applied to the vertical timing unit for synchronizing the vertical timing signal with the vertical synchronizing component of the composite video signal and rendering the vertical timing signal substantially immune to noise which might accompany the composite video signal.

Abstract: In a multichannel head of the type wherein a plurality of transducers scan signal tracks of information across a magnetic tape within a system; and wherein each transducer includes a magnetic core having two pole pieces between which a gap is disposed while at least one turn of a conductor is magnetically coupled to the gap, the plurality of transducers are sequentially bonded together in an integral unit with their gaps disposed at essentially tandem locations.