Abstract: A frequency synthesizer having a frequency-locked loop providing any digitally selected output frequency, and means to frequency modulate the selected output frequency at an audio rate. The frequency-locked loop includes a frequency-to-current converter coupled to the output of a voltage-controlled oscillator to provide a current, representing the actual frequency of the oscillator, which is compared with a current representing a desired output frequency. A resulting error signal controls the oscillator center frequency, which can be frequency modulated by an audio-frequency signal.

Abstract: A modulator includes an output tank circuit energized from a d.c. source through a switching tube and a coupling circuit. The grid of the switching tube is driven by signal-modulated variable width rectangular pulses. The resulting output pulses from the switching tube are used to shock excite the tank circuit and thus produce a carrier wave having an amplitude that varies in accordance with the rectangular pulse width. The trailing edges of the switching tube output pulses are rapidly reduced to zero level by means of an auxiliary circuit that provides spikes of cutoff voltage to the tube grid at the termination of each variable width rectangular pulse. The coupling circuit serves to maintain the anode of the switching tube at a substantially constant voltage level while the tube is conducting so as to provide highly efficient operation.

Abstract: A crystal-controlled oscillator having a switching transistor connected in series with the crystal tank circuit and amplifier of the oscillator.Power consumption is reduced by minimizing the tank circuit capacitance being charged and discharged by the amplifier. The tank circuit capacitance is reintroduced into or coupled to the amplifier circuit during a submultiple oscillation period to receive regenerative feedback from said amplifier circuit to thereby replenish the tank circuit energy losses.

Abstract: Phase-locked loop having a controllable oscillator and a phase detector for generating an output signal which is applied as control signal to the oscillator through a loop filter comprising a storage element, which loop filter is switchable under the control of a control circuit between a first state wherein the loop filter has a wide passband and a second state wherein the loop filter has a narrow passband, provided with an arrangement connected to said storage element for determining the instants at which the instantaneous value of the signal stored in the storage element is equal to the average value of the control signal for the oscillator, the control circuit being arranged such that, after locking, switching-over of the loop filter from the first to the second state is done at one of the instants determined by said arrangement.

Abstract: A phase-locked loop which simultaneously switches both the phase of the reference signal received from the voltage-controlled oscillator of the loop and the sign of the d.c. channel gain. The switching is performed at a frequency lying between the phase of the incident wave and the loop cut-off frequency.

Abstract: This invention concerns a circuit which decreases the time required for certain phase-locked loops to pull in, that is, the time for the frequency of the oscillator which the loop controls to go from some initial error to some specified smaller error. The circuit is utilized with a loop employing an integrating element in the loop filter in conjunction with a logic circuit for indicating out-of-lock condition plus the sign of the frequency error and utilizes a source of direct current (DC) which is connected to the loop filter so as to increase the rate of change of the correction signal to the controlled oscillator and thereby speed-up tuning of the oscillator to the desired frequency.

Abstract: An acoustic wave discriminator comprises an acoustic wave delay line having an input transducer and a plurality of output transducer separately connectable to a phase sensitive detector. This detector measures the phase difference between input and output transducers and provides an output for controlling the frequency of a voltage controlled oscillator. A plurality of different frequencies of the oscillator is obtained by connecting different output transducers of the discriminator to the phase sensitive detector.

Abstract: Dual phase lock loops are used to provide a rapid switching, low power, low purious and fine resolution frequency synthesizer for various radio applications. The first phase lock loop provides for coarse frequency adjustment, and the second phase lock loop includes an arithmetic synthesizer for fine resolution.

Abstract: An induction heating generator consists of a Hartley oscillator employing a tank circuit, including the induction heating coil, disposed in series with the emitter-collector circuit of the transistor. A bias circuit consisting of the parallel combination of a capacitor and diode is connected to the base and the feed-back voltage to the base is generated by a tickler coil. In the absence of oscillations the base is biased for class A operation and the resulting feed-back current charges the bias circuit to shift the operating point to class C operation. The bias voltage is decreased when the tank coil is loaded, lowering its impedance. This maintains stable operation of the oscillator independent of variations in the load. When the coupling between the load and the inductor is so great as to overload the oscillator, the bias circuit prevents oscillation.

Abstract: A multivibrator utilizing two split inverter pairs of MOSFETS and requiring a supply voltage less than the sum of the threshold voltages of the complementary P-N channel devices. The transconductances of each pair are balanced to provide temperature compensation. MOS capacitors can also be utilized. Good frequency stability and low current drain are inherent in the design.

Abstract: A synchronizing circuit for reproducing a synchronizing carrier wave from a received N-phase (N=2.sup.n, n being a positive real integer where n .gtoreq.1) PSK modulated carrier wave and employing a code converter circuit for adjusting the phase states of the received modulated carrier after demodulation thereof in order to enable the modulator to generate signals of the proper phase relation relative to an output carrier wave of a voltage controlled oscillator, which phase relationship is detected by a phase detector.The code converter may be a logic gating circuit having control inputs for changing the output levels or a plurality of branching circuit pairs for each input each pair having a true and complement branch, and switch means for selectively coupling one of the branches to an output associated with each pair of branch circuits.

Abstract: A noise reduction circuit and method are described for implementation in a delta modulation system for signal transmission. Under certain conditions when the delta modulator has selected the minimum step size for encoding and transmission, the present technique and apparatus are effective to change the minimum step size in a way which prevents low level noise generation from occurring in the delta modulation system. The technique and circuit can be utilized with most commonly available delta modulators which have means for changing the step size (i.e., the delta) but is used to the best effect on more stable implementations of delta modulators where an integrator is replaced by a digital accumulator and a digital-to-analog converter.

Abstract: Crystal oscillators have been provided with a voltage sensitive capacitor or varactor which can be varied to improve the frequency stability of the oscillator over the desired range of temperature. A temperature compensator is provided for varying the voltage applied to the voltage sensitive capacitor as a function of temperature. The temperature compensator has a middle temperature range circuit, a cold temperature range circuit, and a hot temperature range circuit. The compensator can be constructed as an integrated circuit with external resistors which can be varied (or trimmed), and provides compensating voltages that stabilize the oscillator frequency over a wide range of temperatures.

Abstract: A frequency synthesizer capable of rapidly changing to a different desired output frequency includes a voltage-controlled oscillator and a variable frequency divider arranged in a phase-locked loop. A first frequency-control voltage is initially applied to the voltage-controlled oscillator to cause a rapid change in its output frequency toward a desired value. Then, the divisor of the variable frequency divider is changed to produce a second frequency-control voltage which precisely sets and maintains the oscillator output frequency at the desired value.

Abstract: A phase and frequency detector includes a first flip-flop triggered by a pulse wave from a reference source, and a second flip-flop triggered by a pulse wave from a voltage-controlled oscillator. Gate means couple outputs of the flip-flops back to reset inputs of the flip-flops so that one of the flip-flops generates pulses having widths proportional to the phase difference of the first and second pulse waves. The gate means inhibits the resetting of the triggered flip-flop when the pulses of the first and second pulse waves do not overlap, so that the triggered flip-flop then generates a continuous output useful for rapidly correcting the frequency of the voltage-controlled oscillator.

Abstract: A demodulation signal results from the sum or difference of two output signals, respectively from two demodulators applied in parallel with the signal for demodulation and in quadrature by a local carrier generator having the same frequency that the one of the received modulated signal.

Abstract: A device and technique for providing stability to a coherent delay line clock. A voltage controllable delay is combined with the lumped delay line of a coherent delay line clock to enable the control of the period of the clock. The voltage controllable delay is obtained by comparing the clock count during a predetermined time period against a fixed number N to obtain a difference count. The difference count is then integrated to form a bias voltage for control of the additional delay. The delay line period will then be a ratio of the predetermined period to the fixed number N, which number may be digitally modified to provide a source of variable frequency.

Abstract: A semiconductor oscillator circuit for very short waves, particularly for UHF, employing the stripline technique and utilizing capacitive voltage division in order to provide feedback. The stripline technique is employed at least, for all the discrete frequency determining (capacitive and inductive) components of the circuit and for the feedback path of the circuit. The series connection of the two capacitors forming the capacitive voltage divider is connected in parallel with a further capacitor, formed in stripline technique, whose capacitance lies in the same order of magnitude as that of one of the capacitors of the capacitive voltage divider and the two capacitors which have the same order of magnitude in capacitance are formed by two conductor electrodes which are parallel to each other at a very small mutual distance with respect to their geometric dimensions, which have a length and width corresponding to their capacitance, and which have a common return electrode.

Abstract: The output of a fast frequency hopping VCO is mixed with the output of a conventional slow acquisition frequency synthesizer to produce an IF which is applied to a frequency discriminator where the IF is compared with a reference IF to provide an error signal which is digitized and stored in a memory. Subsequently, the error signal is applied together with a command signal to the VCO to obtain the desired frequency output.

Abstract: An FSK demodulator is provided with an AFC circuit. The AFC circuit is a negative feedback loop having at least n stable points corresponding to n-level transmitting frequencies. The cut-off frequency of the negative feedback loop is selected higher than the cut-off frequency of the low frequency components from the n-level signals containing a D.C. component which are used to generate the transmitting frequencies.