Abstract: Method and apparatus for protecting a device at a first location using an operational member, within the device at the first location, that is activated by a control unit at a second location, separated from the first location, including an activation switch that enables the generation of a signal for rendering the device operational at the first location.

Abstract: M-ary angle modulation is used to record digital data at high density on a disk. In one embodiment, data symbols are encoded by assigning each data symbol a phase representation in terms of a carrier signal, the disk is physically altered in such a manner as to represent the carrier signal, and, at defined intervals, a phase angle of the carrier signal is changed by one of M of possible phase increments, where M equals two to the power of a number of data bits in a data symbol. M data bits are therefore recorded per each of the defined intervals. In another embodiment, a frequency of the carrier signal is changed to have one of M possible frequencies.

Abstract: A system for retrieving information on a random basis from a disc having the information thereon in a spiral path around the disc. The system includes a turntable rotatable about a central spindle and adapted to support the disc thereon. An arm housing is fixedly mounted over the turntable and contains printed circuit boards having some of the electrical circuitry for the system. Also in the arm housing is a rectangular frame like cartridge holder which supports a cartridge having a stylus therein. The stylus is adapted to ride on the disc to read out the information from the disc. A piston is connected to the cartridge holder and extends through the arm housing. A motor is connected to the piston and is adapted to move the piston so that the cartridge holder is moved with respect to the arm housing and the stylus moves radially along the disc. The motor moves the stylus over the short distance of the radius so as to quickly and easily obtain random access to the information in the disc.

Abstract: A video disc record system having a stylus for recovering information effects kicks which induce limited stylus translations across a disc record surface. Control circuitry responsive to a desired stylus translation are coupled to kicker means for inducing the stylus translation. Actual stylus translations are used to calibrate the kicker activation signals to minimize the kick used to induce stylus translations thereby reducing damage to the disc surface incurred during a stylus translation.

Abstract: Luminance and chrominance components of a video input signal are stored at one rate and recovered at a lesser rate, 1/N, by means of a frame store to effect video signal bandwidth reduction. Burst is not stored but rather is regenerated and added to the video output signal to conserve memory space. To avoid undesirable hue changes and the necessity of rephasing the regenerated burst signal when switching between different video sources, the burst regenerator includes means for forming a product signal from two signals. One signal is locked to incoming burst, and the other signal is derived from a reference source having a phase related to that of burst.

Abstract: Under certain conditions a video disc player can be responsive to externally applied interference signals to provide a defect in the display of the information recovered from the disc. Apparatus is provided between the pickup circuits and the normal defect compensation apparatus of the player to reduce the influence of the modulated carrier in order to enhance the ability to detect the presence of the extraneous signal and take corrective action. The apparatus includes circuits to subtractively combine the signals from the pickup circuits with an amplitude limited version of the signals from the pickup circuits.

Abstract: Under certain conditions a video disc player can be responsive to externally applied interference signals to provide a defect in the display of the information recovered from the disc. Apparatus is provided between the pickup circuits and the normal defect compensation apparatus of the player to detect the presence of the external signals and to activate the normal defect compensation apparatus when the external signals are of a relatively high frequency and above a certain amplitude level.

Abstract: Samples of the amplitude of a quadrature amplitude modulated (QAM) subcarrier signal are taken at times corresponding to each axis crossing of each of the two quadrature related signal components. The polarity of alternate ones of the samples is inverted and the signal is reconstructed from the inverted and non-inverted samples whereby the phase of one of the signal components is reversed without alteration of the phase of the other. Where the QAM signal is a television chrominance signal, means are provided for periodically inhibiting inversion of the samples on alternate lines whereby PAL type chrominance signals may be converted to or from NTSC or NTSC "like" chrominance signals.

Abstract: In a video disc playback apparatus, an active tracking control system is provided using a single pilot signal. The pilot signal is recorded on an information track of a video disc record such that each convolution of the track contains a non-integral number of cycles of the pilot signal. The phase of the pilot signal in a given convolution bears a known relationship to the phase of the pilot signals in the convolutions preceding and succeeding the given convolution. The given convolution includes information representing a reference phase signal. The phase of the recovered reference signal is compared to the phase of the recovered pilot signal which may include phase information from adjacent convolutions to provide an error signal. Pickup positioning apparatus is made responsive to the error signal for maintaining the pickup on the desired path along the information track.

Abstract: Composite color video signals, of the PAL format, are applied to the input of a 1H delay line (exhibiting a 64 microsecond delay, when f.sub.H = 15,625 Hz.). Output of a first comb filter, using additive combination of delay line input and output signals, is applied to a lowpass filter having a cutoff frequency below the lowest PAL color subcarrier sideband frequency. Output of a second comb filter, using subtractive combination of delay line input and output signals, is applied to: (1) a second 1H delay line; (2) a delay device, providing delay correpsonding to a quarter-cycle at the PAL color subcarrier frequency; and (3) a low pass filter having a cutoff frequency below the lowest buried subcarrier sideband frequency. Outputs of two low pass filters are combined to form luminance signal. Outputs of quarter-cycle delay device and second 1H delay device are additively combined to obtain "V" component of PAL signal, and subtractively combined to obtain "U" component thereof.