Abstract: An adaptive audio processor for stereo AM broadcast signals includes independent signal processing paths. Each path has a variable lowpass filter and a matrix and variable Q 10 kHz notch filter to form LEFT and RIGHT channel signals with a 10 kHz notched pass band determined by adjacent channel noise. A 10 kHz pass band signal representative of adjacent channel noise from one of the signal processing paths is compared to a reference to generate a correction signal that is fedback to control the lowpass and notch filters. The correction signal adjusts the pass band and Q of the lowpass and notch filters so that the effects of adjacent channel noise are minimized. Other receiver signals which are reflective of the quality of the received broadcast signal, e.g., the AGC signal, an excess modulation signal, and a receiver microprocessor signal are similarly employed to control the lowpass and notch filters.

Abstract: A Stop On Station (SOS) circuit for a AM and FM radio receivers evaluates field strength of a received station signal and in addition measures and evaluates the frequency of the IF signal so as to assure that the received signal is essentially centered at the IF frequency to identify candidate stations signals which are suitable for listening. The IF frequency for a received candidate station signal is evaluated for an evaluation period of time (e.g., for 40 milliseconds). During each 40 millisecond period, fifteen samples of the frequency of the IF signal are counted and evaluated. If the frequency of the measured signal falls within acceptable limits, a four stage binary persistence counter is incriminated. If a count of 12 or more out of the 15 possible counts is accumulated therein during a 40 ms evaluation period, a station signal is considered to be suitable from a standpoint of received frequency and a "frequency pass" signal is generated.

Abstract: An ajustable switched capacitor circuit comprises a first stage, a second stage and a switched capacitor circuit coupling the output of the first stage to the input of the second stage. The operating parameters of the second stage are a function of the effective resistance of the switched capacitor coupling circuit. An attenuator interposed between the output of the first stage and the input of the switched capacitor coupling circuit controls the charging voltage of the switched capacitor coupler thereby controlling its effective resistance and parameters of the output stage. The signal loss through the attenuator is continuously adjustable responsive to an external control voltage to obtain continuous control of various output stage parameters. The output stage may comprise a filter having the parameters of its transfer function determined by the effective resistance of the switched capacitor coupling circuit.

Abstract: A differential operational amplifier comprises a differential input circuit that provides a differential output signal to a plurality of independent output circuits. The gains of the differential input circuit and one output circuit are set by a fixed bias source. A variable bias source controlled by an external signal determines the gain of each other output circuit so that various attenuation characteristics are obtained in the other output circuits without affecting the operating conditions of the operational amplifier. A feedback element between the output of the one output circuit and the differential input circuit assures gain stability.

Abstract: An audio detector circuit forms L+R and L-R audio signals from an intermediate frequency compatible quadrature amplitude modulated signal in the form (1+L+R)cos(fct+.phi.) where .phi. contains phase modulated L+R and L-R signals. An envelope detector generates an L+R audio signal and in-phase and quadrature phase detectors produce L+R and L-R audio signals, respectively. The difference between L+R outputs of the envelope and in-phase detectors are amplified to generate a cosine correction signal. Each detector includes a differential operational amplifier having an field effect feedback transistor coupled between each amplifier output and the corresponding input and an field effect transistor coupling the compatible quadrature amplitude modulated signal to the operational amplifier inputs.

Abstract: A Phase Locked Loop (PLL) circuit includes a control signal generator, a digital phase detector, logic gates, a charge pump (charge/discharge circuit), a transmission gate, a loop filter, a lead-lag filter and a voltage controlled oscillator (VCO). Outputs of the digital phase detector are coupled through the logic gates to inputs of the charge pump. An output of the charge pump is coupled to the capacitor and to a first input/output of the transmission gate. A second input/output of the transmission gate is coupled to an input of the loop filter whose output is coupled to an input of the VCO whose output is coupled to a first input of the digital phase detector. A second input of the digital phase detector is coupled to a source of a reference frequency signal. The control signal generator generates non-overlapping complementary control signals with one of same connected to the logic gates and the other connected to the transmission gate.

Abstract: An FM stereo radio circuit has an ultrasonic noise detector and an amplitude noise detector each for detecting impulse noise by developing an average noise signal and comparing the average noise signal with an attenuated value of the instantaneous noise signal to generate a noise flag. A dual mode circuit normally operates as a low pass filter for a deemphasis function and is switched by the noise flag to operate as a sample and hold circuit which blanks the noise pulse. The dual mode circuit uses a switched capacitance design and is driven by clock signals to serve as a filter. The clock signals are stopped by the noise flag to effect the sample and hold function.

Abstract: An integrated circuit FM detector which compensates for variations in semiconductor manufacturing process and temperature employs a pair of serially connected switched capacitor-operational amplifier combinations. The first combination is a frequency to voltage converter which uses a switched capacitor input circuit which is clocked at the frequency of the input signal, an operational amplifier and a feedback resistor. The second combination is a compensation circuit which uses an input resistor, a feedback switched capacitor circuit and an operational amplifier. The feedback switched capacitor circuit is clocked at a fixed rate. Reversal of the roles of the resistor and the switched capacitor in the first and second combinations compensates for both temperature and manufacturing process variations.

Abstract: An analog/digital voltage controlled oscillator includes a voltage to pulse converter which responds to a control voltage to generate appropriate control pulses to change the mode of operation of a divider to thereby vary the output frequency of the oscillator.

Abstract: A Phase Locked Loop (PLL) circuit includes a compensation circuit which corrects for non-linear sensitivity of a varactor of a voltage controlled oscillator (VCO) which is part of the circuit. The varactor is employed as a capacitance tuning element. The compensation circuit controls the sensitivity of a charging/discharging circuit (a charge pump) of the PLL circuit with a feedback signal which is derived from an input to the VCO. The sensitivity characteristic of the charge pump is made the complement of the non-linear portion of the VCO sensitivity characteristic.

Abstract: A phase locked loop (PLL) with a narrow bandwidth, and small phase noise which is particularly useful in a FM stereo decoder includes both analog and digital circuitry and has the advantages of both types of systems, performing better than standard PLL's without the need for any external components. An externally referenced digital voltage controlled oscillator, establishes the center frequency of the PLL while analog portions of the circuit permits accurate locking to the input signal and provides a high level of quietness of the system.

Abstract: An attenuator in the composite L-R signal path used for dynamic signal control for blend purposes is limited in range by a static separation adjust signal which attenuates the maximum L-R signal to a value selected for the best right and left channel separation upon matrixing of the L+R and L-R signals. The gain of the L-R signal path is set greater than the L+R path so that a wide adjustment range is available to the separation adjustment circuit.

Abstract: A switched capacitor low pass filter is used to sample an FM stereo composite signal with non-overlapping clock signal to achieve phase or magnitude detection of the 19 kHz pilot without being adversely affected by the presence of information at or about 57 kHz.

Abstract: A switched capacitor pilot cancellation circuit included in an FM stereo decoder signal path which substantially eliminates the 19 kHz pilot from the FM composite by subtracting a reconstructed pilot frequency signal from the FM composite. The reconstructed pilot signal is obtained by applying the DC output voltage of a pilot magnitude detector to a switched capacitor network which is sampled by clock signals which convert the DC to 19 kHz.

Abstract: A method of repairing a leaking coupling between an air conditioning cooling coil and its associated expansion valve using a split clamp-on coupling nut. The nut consists of two mirror-image halves, the two halves being joined together by a pair of screws. The joined together halves provide a passageway sized and partially threaded to accommodate the flanged end of the cooling coil pipe and the threaded end of the expansion valve pipe when these two pipes are aligned along a common axis and the end of the expansion valve pipe abuts against the flange of the cooling coil pipe.

Abstract: A closed-loop attenuator for an FM stereo receiver provides attenuation to the L+R audio signal in a controlled and predictable reaction to an ultrasonic noise (USN) voltage presented to an input amplifier. This is accomplished through a closed-loop circuit configuration including a multiplier which modulates the current output of the input amplifier in accordance with the output of a master differential amplifier and supplies the modulated current to a gain stage connected to the input of the master differential amplifier. The output of the master amplifier is mirrored by a slave differential amplifier which applies the actual audio signal attenuation. The closed-loop configuration confines this linear control action to a very narrow range. Outside of this range, the circuit provides either full attenuation or no attenuation.

Abstract: A current mirror implemented preferably in MOS technology provides low total harmonic distortion and high output impedance and maintains the input signal within one Vgs of the supply voltage source. For an input signal having DC and AC components I and i, a constant curent of 2I is fed to the input terminal. A transistor couples the input terminal to the output terminal. The difference of the constant current and the input current is the output current I-i which passes through the transistor to the output terminal. An amplifier having its input connected to the input terminal and its output fed back to the gate or base of the transistor helps maintain the input terminal at a constant voltage.

Abstract: An audio processor for adaptively rejecting undesired noise and interference in an audio input which includes a variable Q, 10 kHz switched capacitor notch filter. The Q of the notch filter is varied by a control loop responsive to the 10 kHz content of the audio signal. The notch filter includes a summer section that is clocked at a predetermined frequency, and an integrator section which is clocked at a multiple of the predetermined frequency in order to prevent center frequency variation with changes in Q of the notch filter.

Abstract: A collapsible package for extrudable comestibles, such as soft-frozen ice cream, includes a cone-shaped laminated body portion comprised of inner polymer film ply bonded to a structural ply, a nozzle secured at the top of the cone-shaped body portion and a cap or cover across the nozzle aperture. The bond between the polymer film and the structural ply is strippable and has a bond strength of between 65 and 300 grams/inch.

Abstract: A noise blanking signal generator for an AM radio receiver includes a product detector adapted to receive an IF signal modulated by an AF signal and synchronously detect the AF signal, a first low pass filter adapted to derive from the product detector a filtered voltage indicating the average IF signal strength, a second low pass filter adapted to derive from the product detector an AF signal voltage and a reference voltage generating circuit ratiometrically related to the product detector through a common DC power supply and effective to generate a reference voltage substantially equal to the filtered voltage in the absence of an IF signal.