Abstract: A filter structure of inexpensive design that reliably prevents rotation of a filter housing with respect to an outer sleeve of the filter structure is disclosed. More specifically, a connector portion of an end cap of the filter structure is keyed with an opening provided in a receiving end of the outer sleeve to prevent rotation of the filter housing with respect to the outer sleeve. Keying is preferably accomplished by forming the connector portion of the end cap in the shape of a "Double-D", although other shapes may be readily employed.

Abstract: A technique is disclosed to independently tune different sections of a filter by momentarily frequency shifting a first tuned section, preferably by shorting certain nodes in the first tuned section, such that response of a second section can be determined and independently tuned. The first section is returned to normal operation after the second section is tuned.

Abstract: A method and apparatus for securing a television transmission signal from unauthorized reception is disclosed that employs a sideband interdiction technique. A portion of the signal's sideband content is enhanced such that the signal is rendered useless for reception. The signal is decoded by passing the signal through a passive all-pass delay-equalizer network at the site of the receiver.

Abstract: A tuned filter having an improved Q is disclosed in which two or more inductors are placed in parallel to increase the net Q relative to a single inductor of the same net inductance and/or two or more capacitors are placed in series to increase the net Q relative to a single capacitor of the same net capacitance to improve the Q of a tuned filter.

Abstract: A tuned filter having an improved Q is disclosed in which two or more inductors are placed in parallel to increase the net Q relative to a single inductor of the same net inductance and/or two or more capacitors are placed in series to increase the net Q relative to a single capacitor of the same net capacitance to improve the Q of a tuned filter.

Abstract: An in-band television signal scrambling method and apparatus are disclosed which employ a scrambler which receives and scrambles a television signal by suppressing the amplitude of the horizontal synchronizing signals contained therein to a point below the "black" level and which generates whiter-than-white timing pulses in the scrambled television signal for use by a descrambler in reconstructing the suppressed amplitude horizontal synchronizing signals, and one or more descramblers for detecting the whiter-than-white timing pulses in the scrambled television signal and generating therefrom switching signals for a switchable attenuator through which the scrambled television signal passes. The attenuator boosts the amplitude of the suppressed amplitude horizontal synchronizing signals relative to the remainder of the scrambled television signal, thereby restoring the scrambled television signal to an unscrambled condition.

Abstract: An in-band television signal scrambling method and apparatus are disclosed which employ a scrambler which receives and scrambles a television signal and one or more descramblers for restoring the scrambled television signal to an unscrambled condition. A tier level encoding scheme is used to identify and render operative predetermined descramblers. The scrambler encodes tier level coding information in the form of whiter-than-white pulses on a scrambled television signal, these pulses being detected by the descramblers, with only those descramblers identified by the tier level coding information being rendered operative to unscramble the scrambled television signal. The descramblers preferably employ a plug-in module into which the tier level coding information assigned to a particular scrambler can be programmed.

Abstract: A split tuning filter is disclosed in which at least two separate electrically interconnected filter sections mounted on a common circuit board are magnetically isolated through an isolation area defined by a pair of spaced isolation shields. A conductor interconnecting the two filter sections passes through the isolation area and has an external terminal connected thereto which allows each of the two filter sections to be independently tuned, with the isolation area minimizing the tuning impact of one filter section on the other. To further increase magnetic isolation, respective resonating capacitors provided in the filter sections have grounded plates perpendicularly interposed in the line of sight between primary tuning coils which are also respectively provided in the filter sections, with the grounded plates facing toward the isolation shields.

Abstract: A directional coupler for sampling energy traversing a CATV system of the type wherein wide band television signals are extracted from a coaxial transmission line situated at points located at varying distances from the line amplifier. The coupler includes a voltage sensing transformer in shunt with the center and outer conductors of the cable and a current sensing transformer in series with the center conductor. The transformers are wound to provide the coupler with a relatively low tap value. Windings in the shunt transformer are used to internally boost the impedance at the input to the series transformer to maximize return losses and directivity.