Abstract: In television reception, the sound intercarrier signal is detected by mixing the composite sound intermediate frequency signal, which is taken from an output of the video IF amplifier, with a clean, unmodulated signal, which is extracted from the oscillator output of the video synchronous detector and, accordingly, phase locked to the composite video intermediate frequency signal. Complementary amplifier stages, having highly selective tuned matching networks and traps, provide necessary gain and further purification of the respective signals before input to the intercarrier coincidence detector.

Abstract: A high performance video clamp and self-balancing inverter circuit for providing the DC coupling of a video signal together with substantially perfect inversion of any portion of a composite television signal. Under the control of synchronously timed pulses, two switches are alternately turned on and off to selectively apply the video signal to either the inverting or non-inverting input terminal of a video amplifier, thus separating signal portions selected to be inverted from those portions selected to remain non-inverted. To ensure perfect balance between inverted and non-inverted output signals, prior to processing, at least two reference pedestals are added to each field of the composite video signal to raise selected blanking level portions thereof to a level equal to 50% of the reference white level.

Abstract: A rotatable fastener of low torque application, the fastener being characterized by external fastener, bearing surface which comprises a hemispherical dome, said dome defining a head whereby a mating tool may apply torsional forces thereto, the fastener having formation in the dome of a blind cavity the horizontal cross-section of which appears to be concentric to the center axis of the fastener, an axis of the cavity being at an acute angle relative to the central axis of the fastening means, wherein the driving moment between the fastener and a tool is provided by the eccentric relationship of the cavity, relative to the exterior dome of the fastener.

Abstract: An improved pay TV method and apparatus is disclosed, characterized in that the program to be broadcast is encoded to effect electrical inversion of selected groups of lines of the program, thereby to scramble and disguise the video and audio signals. Simultaneously with the encoding of the program, a card is marked with programming, subscriber and area/month identifying information, which card is transmitted to the subscriber. During the actual broadcasting of the program, the subscriber inserts his card into a punch/reader in the subscriber box unit that is connected with his television receiver. When the subscriber selects a program for paid viewing, his subscriber card is punched, and decoder means operable by information contained on the subscriber's card serve to electrically reinvert those lines which were initially inverted by the encoder means, whereby the program is unscrambled for unimpaired viewing, and the sound is made audible.