Abstract: Apparatus for defeating a noise inverter disposed within the IC includes circuitry for changing the amplitude of the AGC signal applied to an AGC amplifier prior to the noise inverter so as to lower the level of the signal fed to the noise inverter. As a result, the signal fed to the noise inverter is less than the threshold signal level necessary for operation of the noise inverter. This enables use of an EIA multiport standard decoder with a standard television signal processing IC wherein the noise inverter is not directly accessible for defeating it.

Abstract: The present invention concerns a high impedance signal source driving a relatively low input impedance mechanical resonating device such as a ceramic filter having an input impedance which varies with frequency. The high impedance source is further loaded by a resonant circuit tuned to the center frequency of the mechanical resonating device. The skirts of the resonant tuned circuit decrease in impedance on both sides of the center frequency of interest substantially compensating for the change of circuit gain with frequency due to the change of input impedance with frequency of the ceramic filter.

Abstract: The present invention concerns apparatus having a voltage controlled amplifier wherein the gain of the amplifier is determined in response to the level of a control signal at an input terminal. A first rate of change is used for a change of gain from a low signal level to a higher signal level, and a second rate of change is used for a change from a high signal level to a lower signal level with the second rate being faster than the first rate.

Abstract: The present invention concerns a non-linear transfer function generator, e.g., for implementating "white stretch" of a luminance signal. Specifically, first and second emitter-follower amplifiers have their inputs coupled in parallel and their outputs coupled in series via first resistor of a voltage divider. A second resistor of the voltage divider is coupled to a point of reference potential. A bias source is coupled to the second amplifier, e.g., via the second resistor of the voltage divider, so that the dynamic response of the second amplifier to an input signal is limited with respect to the first amplifier. The output signal of the first amplifier is linear and an output signal developed at the output of the second amplifier is non-linear. The linear and non-linear output signals are combined by a current steering network in response to a control signal representative of a characteristic of a processed version of the luminance signal.

Abstract: A first amplifier is configured for accepting a signal input and providing a drive signal to a load. A second amplifier is configured in a voltage follower configuration with an input derived from the output of the first amplifier. The output of the second amplifier is coupled in parallel with the first to the load. The output from the second amplifier is nearly an exact duplicate of the output from the first amplifier, and the output contributions from the two amplifiers are therefore substantially equal. Isolation resistors are provided in series with the load and the respective output terminals of the amplifiers for protecting the operational amplifiers from adverse loading conditions.

Abstract: A nonlinear video signal processing system provides gamma correction to improve rendition of picture details near black. In addition, picture brilliance is improved using a brightness and frequency dependent enhancement circuit providing increased detail signal contrast in bright picture areas. In each color channel, the respective color signal is gradually separated into a low level amplitude signal portion and a higher level amplitude signal portion. The higher level amplitude portion is high-pass frequency filtered. The low level signal portion and the high-pass filtered higher amplitude signal portion are added to the original, linear video signal for producing a combined signal coupled to the kinescope. The low level signal portion is DC coupled to the linear signal and the high level signal portion is AC coupled to the linear signal.

Abstract: An oscillator includes a mechanical resonator, such as a crystal, and having an amplifier arranged for oscillating at a first frequency. A resonant circuit is coupled in series with the crystal. The resonant circuit is antiresonant at an undesired harmonic frequency of the crystal thus prohibiting oscillation of the oscillator at said undesired harmonic frequency. The present oscillator is a portion of a phase locked loop used in a television receiver for demodulating a composite stereophonic audio signal.

Abstract: A balanced mixer and output filter for television receivers and the like is presented. The mixer is followed by a fairly selective bandpass filter to protect the IF amplifiers from first and second adjacent channel signals.

Abstract: In a television receiver apparatus is provided for muting an audio power amplifier having continuous operating supply voltage applied thereto from a standby power supply even when the receiver is in an "off" condition so that spurious noise and hum coupled to the power amplifier will not be amplified and heard by the viewer. The muting is applied via a microprocessor controller which controls and senses the power supply status of the receiver as well as mutes the power amplifier in both the "off" and the "on" conditions.

Abstract: An amplifier loaded with a constant bandwidth tuned circuit is provided with an output series coil, and with a resistance in series with the output coil and a subsequent load to provide attenuation at high frequencies for maintaining the total overall gain of the amplifier and tuned circuit load constant with increasing frequency while simultaneously maintaining the bandwidth of the tuned circuit constant with increasing frequency.

Abstract: An apparatus and method for improvement of stereophonic sound. A source of stereophonic sound is provided with two internal loudspeakers and external access to the stereophonic signal. A "wall of sound" effect is achieved by coupling of the sterophonic signal to at least two external loudspeakers with the internal loudspeakers being fed a mixture of the sterophonic signal at reduced power.

Abstract: The present invention concerns apparatus for changing the effective tuning inductance with a change of frequency of a multi-band oscillator, said frequency being controlled in response to the magnitude of a tuning voltage for tuned signal amplifiers so that three point tuning can be achieved in the lowest frequency band between the signal amplifiers and the oscillator. In accord with the present invention, a reactance network is connected in series with the tuning inductor of the lowest band for tailoring the tracking of the oscillator frequency with change of tuning voltage.

Abstract: A level setting apparatus for adjusting the brightness of a television receiver is modified by the setting of an amplitude control apparatus for adjusting the contrast such that the maximum brightness level of the image on a CRT is modified in direct relationship to the adjusted level of contrast.

Abstract: In a color television system, the color signals produced by a luma-chroma IC are summed to produce a signal representative of processed luminance information not otherwise readily available. Pulses of the summed signal corresponding to retrace blanking pulses contained in the color signals, are stripped away in order to reduce errors when attributes of the summed signal are determined, e.g., by an average detector. The detector provides a control signal for modification of a luminance signal, such as by "white stretch".

Abstract: The present invention is for a low buzz television signal processing system. The picture signal is detected by a quasi-synchronous detector wherein the picture carrier is amplitude limited and video tank filtered for insertion into the video mixer for deriving the composite video signal. The sound channel comprises a single parallel resonant tuned circuit forming a bandpass filter with a passband centered at the sound carrier frequency. The modulated sound carrier is fed to a sound detector which is also fed the same filtered picture carrier signal provided by the video tank for providing the 4.5 MHz intercarrier sound signal.

Abstract: The present invention is for a highpass input circuit for a television receiver having an additional trap at a predetermined frequency, e.g. CB frequencies. A M derived constant K high pass filter having an intermediate pi configured filter section is provided with an additional inductor in the shunt leg of the pi section for resonating with the bridge capacitance of the pi section and forming an additional trap at the predetermined frequency. The additional inductor is physically formed by an electrically conductive path etched on a printed circuit board.

Abstract: A very fast peak detector having feedback is presented. A first device charges a storage capacitor to a voltage proportional to the peak voltage of an incoming signal. A second device coupled to the first device in a feedback configuration further charges the storage capacitor with a charging current in addition to the charging current provided by the first device for more rapidly charging the storage capacitor to said voltage proportional to the peak voltage of a low duty cycle short duration incoming pulse. This detector is particularly applicable to a video system having peak luminance detection requirements.

Abstract: A mechanism for mounting a loudspeaker in a front panel includes a plurality of arms having lips affixed to the front panel. A plurality of fingers are affixed to the loudspeaker. The arms and fingers resiliently engage to enable the loudspeaker to be mounted on the panel using a linear motion.

Abstract: The present invention relates to a latch for detachably securing electron cards along orthogonal loading axes. A planar fixed gate is rigidly securable to an external supporting structure and is provided with at least one elongated protrusion extending above one of the planar surfaces. A planar movable gate is rigidly securable to an external electronics mountable structure wherein said movable gate is provided with at least one elongated groove on a planar surface. The planar fixed gate and the planar movable gate are abuttingly engageable to each other with the protrusion matingly fitted within the corresponding groove. The orientation of the protrusion and groove are orthogonal to an axis of a first loading force applicable to the moving gate. A fastener such as a threaded bolt rigidly maintains the planar surfaces of the fixed gate in engagement with the movable gate for rigid support along a second loading axis orthogonal to the first loading axis.

Abstract: A gain controllable amplifier wherein a plurality of signal paths are proed with each of the signal paths having predetermined different gain characteristics. The gain of the total amplifier is selected by application of power supply voltages to amplying stages of the different signal paths with the combination of the level of the voltages determining which signal path will be operational and the total gain of the amplifier.