Abstract: In a multi-phase modulation method in which digital words each having a word length of at least 3 bits control the generation of a modulated carrier in a manner such that each digital word value is associated with a particular amplitude and phase of the modulated carrier, and in which the modulated carrier is formed of a combination of three oscillating signals having identical frequencies, shifted in phase by 120.degree. relative to one another, and each having a selected amplitude, the digital words are associated with the oscillating signals in such a manner that a first group of digital words is represented only by modulated carrier phases which possess equal angular spacings in the 360.degree. phase plane and a plurality of further digital words is represented by a zero amplitude carrier formed by combining all three oscillating signals each having the identical selected amplitude or by suppressing all three oscillating signals.

Abstract: A voltage-controlled oscillator (VCO) comprises a current controlled oscillator (ICO) and control circuitry which independently adjusts the gain (K.sub.v) and free-run or center frequency of the VCO. The control circuitry includes a first current source selected to set the free-run frequency of the VCO and a second current source selected to set the gain (K.sub.v) of the VCO. The current sources are coupled to a common node in a summing/difference configuration. The controlled current generated from the summing/difference configuration is delivered into the ICO. Independent current mirrors are utilized to supply controlled current into the node of the summing/difference configuration.

Abstract: A transmission line microwave oscillator having two degrees of freedom wherein the real portion, R.sub.in, of the input impedence seen by the active device is adjustable by changing the coupling coefficient between and active device and a resonator and where the external quality, Q.sub.EXT, of the oscillator is adjustable by changing the coupling between the resonator and an output transmission line.

Abstract: A digital counter is phased locked to a reference frequency by a voltage trolled oscillator which causes the counter to increase its count rate or decrease its count rate in accordance to the presence of a one or a zero on the most significant bit of the counter at the halfway point of one cycle of the reference frequency. The counter is reset at the end of the cycle of the reference frequency. A single microprocessor which can assess this most significant bit (MSB) and vary the oscillator output, can in this manner control any number of independent phase lock loop circuits.

Abstract: In order to deliver an angle-modulated output signal as a function of digital information, the frequency synthesizer delivers an output frequency F.sub.S =(N+k)F.sub.R, where N is the integral part of a number N+k and F.sub.R is a reference frequency. Provision is made for a variable oscillator, an oscillator control loop comprising in series a variable divider having a preselected divisor N, a phase comparator for receiving the reference frequency and a summing device. The synthesizer further comprises a phase accumulator for performing, at the frequency F.sub.R, modulo-M summation of a number G=k(M) applied to its input. The sum and carry outputs of the accumulator are coupled respectively to the summing device in order to deliver a signal for compensating the signal delivered by the phase comparator and to the divider for delivering a control signal to select the divisor N+1.

Abstract: The inherent temperature instability of surface acoustic wave (SAW) clock oscillators is improved by the use of a thermometer oscillator circuit that senses temperature changes in the SAW substrate. The thermometer oscillator is used in combination with a calibrated programmable read only memory and a logic circuit and provides frequency corrections to the clock oscillator. The basic device is an oscillator clock circuit using a SAW substrate having a delay path orientation with good temperature stability. A second oscillator, the thermometer oscillator circuit, and the electronic compensation scheme are added in order to produce minimum temperature coefficient of delay over all temperatures in the range of interest. The thermometer oscillator delay path utilizes a high temperature coefficient of delay orientation of the same SAW substrate and at an appropriate angle to the clock oscillator delay path orientation.

Abstract: A phase sychronizing circuit for a device which reproduces digital data has a phase locked loop including a first phase comparison circuit, a voltage controlled oscillator (VCO) producing an output the frequency of which is controlled by the first phase comparison circuit, and a first frequency divider to divide the output frequency of the VCO. The phase synchronizing circuit further includes second frequency divider for dividing the output frequency of the VCO, a second phase comparison circuit for comparing the phase of a first clock signal from the first frequency divider, with that of a second clock signal from the second frequency divider and a circuit for controlling the frequency dividing ratio of the first frequency dividing circuit according to the phase difference between the first and second clock signals in such a way that the frequency dividing ratio becomes one of 1/N, 1/(N+1) and 1/{(N+(N+1))/2} wherein N is a positive integer.

Abstract: In an FSK demodulator, the output of the phase detector of a phase locked loop (PLL) is capacitively coupled to one input of an FSK voltage comparator, the capacitive coupling blocking d.c. and d.c. being restored at the comparator input by diodes connected between the two comparator inputs. The other input of the comparator is supplied with a reference voltage corresponding to a nominal center frequency of the FSK signals. A buffer amplifier permits rapid charging of the coupling capacitor, which is set to a determined state when there is no phase lock of the PLL. The arrangement facilitates demodulation of narrow-band FSK signals whose center frequency is subject to change.

Abstract: A frequency stabilized oscillator includes a rectangular resonant cavity having a ground or short circuit wall, an H wall, and a top wall having an inductive window therein. A solid-state oscillating device such as a GUNN diode is attached at one end thereof to the short circuit wall, and a disk type dielectric resonator is supported from the short circuit wall and is located substantially adjacent the solid-state oscillating device so as to electromagnetically couple with the oscillating device. The inductive window is located so as to be in substantially overlying relationship with the dielectric resonator. A strip conductor is attached to the upper end of the oscillating device and extends through the H wall to the exterior of the oscillator to thereby provide a DC supply terminal for the oscillating device. The H wall of the resonant cavity is isolated from the DC supply applied to the strip conductor by means of a thin insulating layer between the strip conductor and the H wall.

Abstract: A method and apparatus for phase modulating a carrier signal to convey an information signal (12) such that the carrier signal has a constant amplitude envelope. A Hilbert transform signal (14) of the information signal (12) is produced. The signals (12, 14) are sampled to produce signals (16, 18), which represent cartesian coordinate values. The cartesian coordinate values are then converted into equivalent polar vectors (20-36) which have both an amplitude (R) and an angle (.theta.). The polar vector quantity (R,.theta.) is converted into two unity amplitude vectors (A, B). The unity amplitude vectors (A, B) are offset from the polar vector quantity by an angle the cosine of which is proportional to the amplitude of the polar vector (R). The carrier signal is sequentially phase modulated by each of the angles of the unity amplitude vectors (A, B) for each sample period of the information signal.

Abstract: The fullwave bridge envelope detector comprises first, second, third, and fourth rectifier circuits each of which are coupled to receive first or second alternating input signals which are 180 degrees out of phase. The first and third rectifier circuits each include a diode connected transistor and an additional transistor coupled in current mirror relationship therewith so as to produce halfwave rectified versions of the first and second alternating input signals respectively. The second and fourth rectifier circuits each comprise a transistor which is rendered conductive when first and second alternating input signals respectively become negative. The halfwave rectified signals produced by the first and second rectifier circuits and the halfwave rectified signals produced by the third and fourth rectifier circuits are summed at an output node to produce the fullwave rectified version.

Abstract: The disclosed FSK demodulator includes a digital PLL for converting an FSK modulated input signal with two different frequencies to rectangular waveforms having durations as determined by those frequencies, two reversible N bit counters for counting clock pulses to determine instantaneous duty factors in the form of N parallel bits of the waveforms for each pulse repetition period, and a read only memory for multiplying alternate outputs, except for the sign bit, from the counters by a ratio of the lower to the higher frequency of the input signal. Then, a digital first-order low-pass filter removes a high frequency component from the output of the read only memory, resulting in a demodulated binary signal. The binary signal may be produced by setting or resetting a FLIP-FLOP when the sign bit from each of the counters is respectively a binary ONE or ZERO. Alternatively, another reversible M bit counter (when M>N) may count the clock pulses to equal the output from the read only memory.

Abstract: To extend the variation range of a controlled frequency oscillator comprising a piezoelectric element, a lithium tantalate or lithium niobate element is used in parallel with which there is connected a linearization circuit comprising an inductance in series with a parallel circuit comprising a resistor and a capacitor.

Abstract: A semiconductor integrated circuit using charged coupled device (CCD) technology for performing demodulation of time-varying signals which have been phase or amplitude modulated. The CCD circuit performs a sampling of the time-varying signal at a suitable sampling frequency depending upon the frequency of the phase or amplitude modulation of the carrier. The CCD device converts the sample into an equivalent charge packet which is used to control the control electrode of a field effect transistor in an amplifier circuit. The magnitude of the sample is representative of the amplitude of the carrier so that the output of the field effect transistor represents a demodulated signal. The circuit is a broad spectrum device, operable with a signal frequency from the audio into the gigaHertz (GHz) frequency range.

Abstract: A frequency control system with a phase-locked loop for automatically adjusting the frequency of an alternating signal and an external signal derived coherently therefrom to the variant zero phase-shift frequency of a phase shifter adapted to receive the external signal, the control system comprising: a phase shifter responsive to the external signal for introducing a frequency sensitive bipolar phase-shift to the external signal to produce a phase shifted external signal thereat, the phase shifter introducing zero phase-shift at a drift-prone frequency, f.sub.o ; an alternating signal source for generating the alternating signal of adjustable frequency covering a range of frequencies including frequency, f.sub.

Abstract: In a control circuit for a voltage-controlled oscillator including the combination of: (a) a source of D.C. power, the voltage out of such source being adjustable in discrete steps to provide a coarse frequency control signal; (b) a control loop, responsive to the signal out of the voltage-controlled oscillator, to provide a fine frequency control signal; and (c) a summer to combine the coarse and fine frequency control signals into a single frequency control signal for the voltage-controlled oscillator, an improvement is shown wherein the control loop comprises an interferometer wherein noise extant on the signal out of the voltage-controlled oscillator is degenerated by dividing a portion of such signal into a reference path, a delayed path and a parallel path, the signals in the latter two paths being processed to produce an amplitude corrected signal for combination with the signal, shifted by 90.degree., in the reference path, finally to produce the fine frequency control signal.

Abstract: Transferred-electron device (TED) microwave burst and single pulse generators which are triggered by picosecond optical pulses. The burst generator includes a TED having a cathode, an anode, and a gate electrode positioned therebetween, all located on a semiconductor substrate. An optical pulse applied to the substrate between the gate and anode electrodes causes a plurality of space charge domains to sequentially travel from the gate to the illuminated region thereby causing an oscillatory burst of current to occur in the external leads of the TED. The frequency of the burst is proportional to the distance between the gate and the illuminated region and the burst duration is proportional to the optical pulse amplitude and/or duration. Alternatively, the burst generators may be formed from a two terminal TED with the cathode electrode being treated as the gate. A single pulse generator may be formed by applying an optical pulse to the substrate between the cathode and the gate of a three terminal TED.

Abstract: In an FM demodulation circuit which demodulates an FM signal by the use of a phase-lock loop constructed of a phase comparator, a loop filter and a voltage-controlled oscillator, the loop filter is a variable loop filter whose loop band width is varied in correspondence with the modulation band width and the carrier/noise ratio of the input signal by a base band processing circuit.

Abstract: A highly stable voltage variable crystal controlled oscillator adapted for stand-alone use or for use with an atomic clock for further stabilizing the oscillator. A novel Colpitts crystal oscillator configuration is employed and utilizes an FET amplifier and bipolar emitter follower configured for power gain without phase shift in the feedback circuit. The oscillator output signal is derived through the crystal which then acts as its own low pass filter to improve the purity of the output signal. A novel buffer/amplifier circuit including a grounded gate FET amplifier and coupling transformer assure frequency stability despite wide ranging load impedance variations. A resilient thermal foam material is used to enclose the temperature and shock sensitive components of the oscillator to provide further frequency stability and rugged construction.

Abstract: Asynchronous digital frequency shift keyed (FSK) signals are demodulated by using an autocorrelation type demodulator including digital integration. To this end, the autocorrelation function and digital integration are realized by generating integration increments, i.e., area increments, at the digital signal sampling points and accumulating them to obtain the integrated output. This is realized by turning to account a relationship between zero crossings of the received signal, zero crossings of a delayed version of the received signal and polarity of the product of the received signal and its delayed version relative to sampling points of the received digital signal. Specifically, the area increment in an n.sup.th sampling interval is determined by the time interval since the last zero crossing of the received signal before the n.sup.th sampling point, the time interval since the last zero crossing of the delayed signal before the n.sup.th sampling point and the polarity of the product signal at the n.sup.