Rca Inc.

Rca Licensing Corporation

James Hettiger

Robert L Shanley, Ii

Leopold A Harwood

James C Tallant, Ii

Wesley W Murphy, Iii

Sanjay R Vinekar

Karl L Friedline

Nathaniel H Ersoz

A ferrite shield component for suppressing high frequency signals in electrical circuits, such as tuners for television receivers, is formed by surrounding an electrical conductor with ferrite material. The shield component is formed in the shape of a leadless chip to permit placement on a circuit board by chip insertion machines. The conductor pattern and ferrite material may be selected to determine particular impedance-frequency characteristics.

Chip component providing rf suppression

A superheterodyne receiver having a plurality of selectable bands includes a tuning voltage source and a band selection signal source. To improve tracking, the receiver includes a selectively enabled voltage modifying arrangement responsive to the band selection signal for providing a modified tuning voltage to one of the radio frequency and local oscillator tuning circuits when the tuning voltage is within a predetermined portion of its range.

Tuning voltage tracking arrangement

In a superheterodyne receiver, such as a typical television receiver, a radio frequency coupling arrangement includes a first resonant circuit coupled to receive the input signal and further coupled to a second resonant circuit by a first coupling. Both resonant circuits are tuned to the desired signal frequency. The capacitive branch of the first resonant circuit includes a circuit impedance for providing a neutralizing voltage, at least a portion of which is coupled by a second coupling to the inductive branch of the second resonant circuit. The circuit impedance is selected to cause cancellation in the inductive branch between image frequency components coupled by the first coupling and image frequency components coupled by the second coupling, without substantially affecting the desired signals.

Tracking image frequency trap

A multiband local oscillator of a television tuner comprises a common collector transistor amplifier, a feedback circuit for conditioning the amplifier to oscillate in the wide range of frequencies for VHF broadcast and cable channels and a tuning circuit coupled to the base electrode of the transistor. Bandswitching signals are applied to switching diodes in the multiband tuning circuit to produce tuned circuit configurations for the various frequency bands. When one band is selected, the corresponding bandswitching signal is coupled to the switching diode associated with a lower band to turn it on as well as the switching diode for the selected band to inhibit out-of-band oscillators due to parasitic elements of the tuning circuit.

Tuning circuit for a multiband tuner

An interstage coupling network is provided comprising a series connection of an even number of reactive elements coupled between the input and output terminals of the interstage network, a junction point of said series connection of inductors being coupled to a signal reference potential via a first reactive shunt element. A series connection of oppositely-poled switching diodes is coupled in parallel with a portion of said series connection of reactive elements, the junction between the series-coupled diodes being coupled to the signal reference potential via a second reactive shunt element. A third reactive element is coupled between the network output terminal and a point on the series connection of reactive elements which is remote from the input terminal of the network.

Bandswitched interstage coupling network including a high side coupled

In a color TV receiver incorporating automatic kinescope bias (AKB) control circuits, a first train of monolevel pulses with timing suitable for retrace blanking purposes and a second train of monolevel pulses with 'backporch' timing appropriate for burst gating purposes are applied to a circuit serving to generate at a first terminal a train of bilevel pulses exhibiting a first voltage level during periods of overlapping of the pulses of the first and second trains, and exhibiting a second, lesser voltage level during the remaining, non-overlapping portions of the pulses of the first train. A resistor interconnects the first terminal with a second terminal. A keyed voltage source, responsive to a third train of monolevel pulses timed to indicate recurring kinescope bias control intervals, develops a voltage of a third level, intermediate the first and second voltage levels, at the second terminal during the recurring control intervals. The keyed voltage source exhibits, during the control intervals, an output impedance significantly lower than the impedance exhibited by the interconnecting resistor. During periods intervening successive ones of the control intervals, the voltage source is effectively disabled and exhibits an output impedance significantly higher than the impedance exhibited by the resistor.

Trilevel sandcastle pulse encoder

A color TV receiver is provided with an encoding/decoding system for a trilevel sandcastle pulse train, exhibiting a middle pulse level during recurring kinescope bias control intervals, and comprising excursions between a base level, a low pulse level, and a high pulse level during periods outside said kinescope bias control intervals. The system's decoder includes a trio of voltage comparators for comparing incoming sandcastle pulses with respective reference voltages derived from three different intermediate points on a common voltage divider connected across the terminals of a DC supply. The system's encoder includes keyed means for determining the middle pulse level of the trilevel sandcastle pulse train in accordance with the output of a second voltage divider connected across the same DC supply as the first voltage divider. An output of a third, selectively enabled, voltage divider, connected across the same DC supply as the first and second voltage dividers, is determinative of said low pulse level. The third divider is subject to modification during base level appearances, with the base level determined by the third divider's modified output during the periods of divider modification. During high pulse level appearances, the third voltage divider is disabled to establish the high pulse level at or near the full output potential of the DC supply.

Trilevel sandcastle pulse encoding/decoding system

A dynamic noise filter especially adapted for use in audio reproduction systems within a television display device is provided to eliminate perceived noise. An audio signal having a relatively wide frequency range is passed through a variable bandwidth lowpass filter, the upper frequency cutoff point being variable in response to a control signal. A control path includes a filter and detector circuit for generating the control signal in response to the amplitude of the audio signal within an upper frequency portion of the audio signal frequency range. The control signal controls the bandwidth of the lowpass filter inversely with respect to the level of the audio signal within the upper frequency portion of the frequency range. A further filter is included in the control path for providing substantial attenuation at the fundamental frequency and lower order harmonic frequencies of the television horizontal line scanning signal in order to prevent the control path from erroneously responding to this signal.

Dynamic noise filter for an audio signal in a television

In an automatic kinescope bias (AKB) control system, a signal with a magnitude representative of the black current level conducted by the kinescope of a television receiver is derived from a sense point. The derived signal is coupled via a signal path to a processing network including input clamping and sampling networks for developing a bias correction voltage. A source of auxiliary control signal, coupled to the signal path prior to the clamping network, is subject to being undesirably influenced by impedance variations manifested by the sense point. An impedance included in the signal path between the sense point and the auxiliary signal source compensates for the sense point impedance variations, and also increases the immunity of the clamping network to spurious signals including noise and locally generated interference.

Automatic kinescope bias control system compensated for sense point

A television receiver includes a DC coupled video output amplifier for supplying video signals to the cathode of an image reproducing kinescope, and an automatic kinescope bias (AKB) control system for maintaining a desired cathode black image current level. A video processor supplies video signals to the output amplifier via an input network including a manually adjustable resistor for pre-setting the amplifier gain. During AKB operating intervals, a substantially zero voltage drop is maintained across the adjustable gain control resistor so that the setting of the adjustable gain control resistor desirably has no influence on the kinescope cathode bias voltage monitored by the AKB system.

Manually gain presettable kinescope driver in an automatic kinescope

A pulse generator for a television receiver produces keying pulses during the video signal back porch interval in order to energize burst gate and brightness control circuitry. The pulse generator is triggered by horizontal sync pulses under strong, noise-free video signal conditions. As the quality of the video signal and the horizontal sync pulses deteriorate due to noise or a weakening signal, the pulse generator is triggered by horizontal retrace pulse in order to provide keying pulses under all video signal conditions.

Burst gate keying and back porch clamp pulse generator

A DC coupled system for automatically controlling the high frequency peaking content of a video signal is disclosed. The system includes a DC coupled control path comprising a peak detector for developing a control voltage representative of the high frequency content of the video signal exclusive of video signal DC components, and is preceded by a video signal amplifier. A filter for shaping the frequency response of the control path is connected to the amplifier. A manually adjustable peaking control for controlling the DC bias of the amplifier is also connected to the amplifier. The filter and adjustable peaking control exhibit mutually independent operation, and are both connected to the amplifier via the same single terminal.

Video signal peaking control system with provision for automatic and

A DC coupled system for automatically controlling the high frequency peaking content of a video signal is disclosed. The system includes a DC coupled control path comprising a peak detector for developing a control voltage representative of the high frequency content of the video signal exclusive of video signal DC components. The detector is preceded in the control path by a frequency selective network comprising an amplifier and a filter for shaping the frequency response of the control path such that high frequency video signal components exclusive of DC video signal components are passed to the peak detector. The frequency selective network comprises the cascode combination of a video signal amplifier transistor and a current source transistor which provides quiescent operating currents for the amplifier transistor. The filter is coupled to the junction of the amplifier and current source transistors, and includes a DC blocking network coupled between the junction and a point of reference potential.

Frequency selective DC coupled video signal control system insensitive

A DC coupled system for automatically controlling the high frequency peaking content of a video signal is disclosed. A peak detector develops a control voltage representative of the high frequency content of the video signal. The control voltage controls a differential control input peaking signal splitter to provide controlled amounts of complementary phased peaking signals, which are differentially combined with complimentary phased video signals to produce a controllably peaked video signal. The differential control inputs of the peaking signal splitter receive balanced quiescent bias from symmetrical bias coupling networks, one of which includes the peak detector.

Predictably biased DC coupled video signal peaking control system

An automatic kinescope beam current limiter for a television receiver includes a source of derived beam current representative voltage, a keyed sampling circuit for developing an output beam current control voltage on a charge storage capacitor in response to the derived voltage, and an auxiliary current path including an impedance coupled between the output capacitor and the source of derived voltage. In a normal beam limiting control mode, the control voltage from the sampling circuit serves to modify the television signal in response to the derived voltage in a direction to limit excessive beam current. In an abnormal control mode such as when the sampling circuit is inoperative due to disrupted keying, current is conducted via the auxiliary current path in response to the derived voltage to modify the control voltage on the capacitor with a sense and at a rate for limiting excessive beam current, to thereby preserve beam limiting capability.

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Indianapolis, IN, United States of America

James Hettiger