Abstract: Quadrature detectors are subject to errors due to both phase and amplitude mismatches. The disclosed invention comprises a system for sampling the I and Q channel output signals of a quadrature detector and processing these signals to generate a signal which has a predetermined relationship to the phase error in the in-phase and quadrature signals independent of amplitude mismatches in said signals. The necessary mathematical computations can be performed by analog or digital circuitry. Phase error correction can be accomplished by a servo loop which changes the relative phase of the reference signals to the I and Q channels or by mathematically correcting the I and Q channel output signals to reduce the phase error.

Abstract: A combined phase-locked loop frequency demodulator and frequency synthesizer for frequency-modulated wave receivers using two phase-locked loops respectively for synthesis and for demodulation. In this device, the frequency-modulated signal is applied to one of the inputs of a first phase comparator whose other input is coupled to the output of a voltage-controlled oscillator, which output is also coupled, through a prescaler and a programmable frequency divider mounted in cascade, to one of the inputs of a second phase and frequency comparator whose other input is coupled to the output of a crystal-controlled reference oscillator. The output of the first comparator is coupled by means of a first low-pass or bandpass filter to a first input of an analog adder whose second input is coupled by means of a second low-pass filter, having a relatively low upper cut-off frequency, to the output of the second comparator.

Abstract: An integrated circuit demodulator receives an alternating signal at a first frequency and an alternating signal at a second frequency and provides a binary output corresponding to the first and second frequencies. An input signal is received by a first and a second frequency filter. If the input signal is the first frequency, then it is attenuated in the second frequency filter and vice versa. A positive full wave rectifier receives the first frequency signal and provides a positive full wave rectification thereof. A negative full wave rectifier receives the second frequency signal and provides a negative full wave rectification thereof. The rectifications are summed in an operational amplifier, thereby providing a difference so that the positive rectification is reduced by the attenuated negative rectification and the negative rectification is reduced by the attenuated positive rectification. A binary output is thereby provided.

Abstract: A circuit for supplying first and second currents to a load comprises two current generators for providing those currents during first and second time intervals and a resistance through which those currents flow. Two control potentials developed by two semiconductor junctions are applied across the resistance. First and second control circuits control the two current generators so that the first and second currents are provided during the first and second time intervals, respectively. The current supply circuit is useful in a multivibrator wherein the timing capacitor thereof is the load to which the first and second currents are supplied.

Abstract: The starting frequency and sweep rate of a chirped frequency-shift-keyed oscillator are automatically controlled for correction of long-term drift. The substantially linear swept frequency output of the oscillator, during each of a successive multiplicity of swept frequency chirps, is counted and the count converted to an error signal utilized to control an appropriate potential in the oscillator circuit. The initial frequency is monitored, where the swept frequency range is small compared to the initial frequency, by counting the number of cyles during a chirp period in obtaining a first error signal from the total cycle count. The frequency-chirp ramp rate is monitored by counting the number of cycles during an initial portion, e.g.

Abstract: A coherent array of Josephson oscillators is provided. Individual hysteresis-free Josephson junctions are longitudinally arranged in a line and have such a spacing as to substantially eliminate quasiparticle interactions. To provide a common frequency of operation, equal and opposite dc voltages are produced in adjacent pairs of the Josephson junctions by an arrangement of interlocking dc SQUID's (Superconductive Quantum Interference Device) connected to transversely extending biasing leads. Phase coherence for the array is provided by a rf current circulating in an inductive feedback path that loops between the ends of the array.

Abstract: A coherent array of Josephson oscillators is provided. Individual hysteresis-free Josephson junctions are longitudinally arranged in a gap of a central conductor in a line and have such a spacing as to substantially eliminate quasiparticle interactions. To provide a common frequency of operation, equal and opposite dc voltages are produced in adjacent pairs of the Josephson junctions by an arrangement of interlocking dc SQUID's (Superconductive Quantum Interference Device) connected to the longitudinal central conductor using microwave bias tees. Phase coherence for the array is provided by a rf current circulating in an inductive feedback path that loops between the ends of the array.

Abstract: A typical coaxial circuit which couples a negative resistance diode to the cavity of a power combiner consists of a metallic rod which is biased by a spring against the diode supported by a carrier which is effective to vary the position of the diode along the longitudinal axis of the rod. The rod cooperates with bores in a block to comprise, in series, between the diode and the cavity, a transmission line whose length varies in accordance with diode position, a fixed impedance transformer and a fixed length transmission line.

Abstract: If a piezoelectric crystal is used in circuits containing ICs with low supply voltage, the additional capacitors required in oscillator or filter circuits cannot be implemented as junction capacitances. To eliminate the need for additional discrete capacitors, these capacitances are implemented with additional films on the crystal.

Abstract: A frequency modulation detector, includes an FM (frequency modulation) demodulator, an adder responsive to first and second signals for maintaining a constant D.C. level output signal, the first signal being the FM signal, and a feedback circuit connected to the adder for comparing the D.C. output level of the adder with a reference signal level to produce the second signal.

Abstract: A method and apparatus for stabilizing the resonance frequency of a rubidium frequency standard utilizes control of the intensity of the rubidium-87 lightbeam between the rubidium lamp and rubidium vapor cell. Resonance frequency stabilization is achieved by the present invention by providing adjustment of pumping light intensity until the sensitivity of resonance frequency to changes in cell temperature is minimized and the cell operating temperature is at its turning point, that is, where resonance frequency shift versus temperature goes through a zero slope. By utilizing the invention, the light crossover point, that is, a point of convergence of the family of curves of frequency deviation versus temperature for different levels of rubidium lamp excitation discharge current, can be set equal to the cell turning point.

Abstract: The demodulator combines a conventional frequency discriminator with a bandpass filter for removing the noise which is present from the band occupied at a given instant by the modulated signal. The center frequency of the bandpass filter is controlled in dependence on the instantaneous frequency of the modulated signal and its bandwidth b.sub.u is controlled in dependence on the instantaneous width of the band occupied by the modulated signal.

Abstract: A switched-capacitor modulator for quadrature modulation is disclosed. The modulator of the present invention provides a means for simultaneous modulation of two carrier signals in quadrature by two input signals in such a way that the gains of the two modulations are exactly the same. In accordance with the invention a switched-capacitor modulator is provided having a plurality of input signal sources for quadrature amplitude modulation. The invention provides for a single common switched-capacitor network with multiple switches or multiple switched-capacitor networks for each incoming modulating signal. A switched-capacitor network utilized to form and modulate a carrier signal for shaping the carrier to reduce sidebands of the third and fifth harmonics in the modulated signal is also disclosed.

Abstract: The output frequency of a phase locked loop frequency synthesizer is measured by a counter which counts whole output cycles and a timer providing a signal proportional to a fractional output cycle during a sampling period. The counter output is stored into a latch at each sampling period. Calculated frequency is generated by an accumulator which is incremented a selectable integer N at the completion of each sampling period. The accumulator output is divided into a first part relating to whole cycles and a second part relating to fractional cycles. An adder takes the difference of the latch stored number and the accumulator output first part. The resulting difference, with the accumulator output second part restored thereto, comprises a coarse error signal in digital form. The digital coarse error signal is converted to analog and applied as one input to a summer. A second input to the summer is provided by the timer signal after being scaled proportionately to N in a multiplying D/A converter.

Abstract: An energy synchronized demodulator circuit is disclosed having a differential input to single ended converter coupled to a sync detect circuit which provides a detection signal in response to the modulated input signal. The detection signal is integrated over time, and a threshold detector provides an output when the detection signal exceeds a predetermined threshold level. A filter provides a constant level output signal indicative of the presence of valid data. Synchronized demodulation is provided by a correlation between phase or frequency in predetermined bit intervals of the detection signal. Synchronization is initiated by the initial burst of input signal energy received by the differential input.

Abstract: A temperature compensating circuit for a piezoelectric crystal includes a thermistor circuit coupled to a transistor to cause the output voltage derived from the transistor to decrease as the temperature increases from a cold temperature toward a middle temperature. As the temperature increases still more, the thermistor causes the transistor to become saturated, and its output voltage increases. An additional thermistor circuit is coupled to the transistor output to cause the output voltage to decrease as the temperature increases toward a warm temperature from the temperature at which the transistor became saturated.

Abstract: An improved oscillator circuit primarily for use as an RF source circuit for igniting a light discharge in a rubidium lamp used in a rubidium vapor cell frequency standard. A number of novel features are disclosed including an adjustable power capability dependent on current sensed feedback providing power adjustment over at least a 5-to-1 ratio; lamp heater monitoring for high oscillator power operation during warm-up; and light intensity monitoring for feedback bypass and high oscillator power operation whenever inadequate light discharge is detected.

Abstract: A phase-lock loop is disclosed for synchronizing an oscillator signal with a train of input signal pulses, some of which may be missing. The phase-lock loop is of particular use in a decoder for decoding digitally encoded data employing a self-clocking coding scheme. The decoder generates a clock from the input signal stream for use in the decoding process.

Abstract: A novel signal synthesizer provides high frequency synthesized waveforms for the user. By converting phase information into digital outputs in parallel and by selectively coupling these digital outputs, an ordered digital output is formed to provide the high frequency waveforms. This ordered digital output, which represents points on a sine function, is converted to an analog signal for the synthesizer output. Furthermore, frequency and phase modulations of the synthesized waveforms are easily implemented with this novel signal synthesizer; the modulation information is simply added to the digital outputs prior to selectively coupling. Thus when the ordered digital output is converted to an analog signal, the analog signal contains the modulation information.

Abstract: In an assembly of a piezoelectric crystal and an IC on a substrate, additional capacitors, such as load capacitors of a crystal oscillator, are designed as blocks for mounting the crystal on the substrate at its vibration nodes.