Abstract: A tunable oscillator develops a signal having a frequency variable over a range of frequencies in response to a control signal. A frequency determining resonant circuit includes two voltage-variable capacitance diodes in an arrangement for adjusting at least one endpoint of the frequency range. As a result, the relationship between the magnitude of the control signal and the frequency of the oscillator signal can be adjusted while avoiding mechanically adjustable reactive elements. The disclosed arrangement is suitably employed with resonant circuits other than those in oscillators.

Abstract: A voltage controlled oscillator includes a main varactor diode coupled to a frequency resonating circuit to produce an output frequency in response to a control voltage. A secondary varactor diode of an appreciably lower voltage to frequency sensitivity ratio is coupled to the main varactor diode. A modulation input circuit is coupled to the secondary varactor diode to enable modulation of the resonating output frequency. A linearizing circuit is coupled to the secondary varactor diode and tracks the main varactor diode capacitance to continuously adjust the bias voltage of the secondary varactor diode to provide constant carrier modulation deviation.

Abstract: In a frequency synthesizer phase locked loop including a reference oscillator, a variable reference divider (.div.M), a sample and hold phase detector, a loop filter, a voltage controlled oscillator and a variable divider (.div.N), a voltage converter for controlling the voltage of a control input to the voltage controlled oscillator is disclosed. In the preferred embodiment, the voltage converter has its input connected to the output of a first reference divider in the variable reference divider (.div.M) and its output connected to a control input (varactor diode) of the voltage controlled oscillator. The voltage converter clamps the divider reference signal from the first reference divider and provides a negative voltage level output to bias the varactor diode of the voltage controlled oscillator. Thus, the tuning range of the frequency synthesizer is increased.

Abstract: A phase-locked loop for use in the common T1 systems. The phase relationship of the clock pulse output of a voltage controlled oscillator is determined with respect to an incoming data pulse train. If the clock signal leads the data signal, an error signal of a first polarity is applied to an integrator whose output is provided to the VCO to reduce the frequency of the clock pulse. If the clock signal lags the data signal, an error signal of a second polarity is applied to the integrator whose output is provided to the VCO to increase the frequency of the clock pulse. The logic of the circuitry is such that the output of the integrator is always either increasing or decreasing, even if there is zero phase error between the clock pulse and data pulse (i.e. the loop has infinite gain for zero error). The integrator continues to integrate in a first direction until the frequency of the clock pulses is adjusted so far that the lead is changed to a lag or vice-versa, with respect to the next data pulse.

Abstract: An adjustable frequency synthesizer primarily for use in an atomic frequency standard of the type used for stabilizing a frequency source by locking it to the hyperfine transition resonance of an atomic frequency resonator. The synthesizer is programmable by an externally applied code to provide the proper frequency, electromagnetic resonance field to the atomic frequency resonator. The synthesizer also provides a phase locked frequency modulating signal to produce the resonance deviation signal in the resonator. The broad range and fine frequency increments of the synthesizer permit accommodation of a wide range of resonance frequencies in the atomic frequency resonator to obviate resonator gas pressure and magnetic field variations which would otherwise decrease the production yield of such resonators.

Abstract: A non-linear phase detector is disclosed which compensates for gains occuring during tuning a frequency generator of a known phase locked loop circuit which incorporates a Varactor tuned resonant circuit as a VCO. The phase detector is of the sample and hold type and incorporates a Varactor rather than a hold capacator to compensate for non-linear gains which occur when tuning the frequency generator across its band spread. Additionally, bias compensation is provided for the resonant circuit Varactor to offset its contact potential.

Abstract: An oscillator arrangement is disclosed which is controllable in its frequency and which comprises a control input for frequency variation and a transformer output, whose frequency-determining oscillating circuit possesses, as a controllable reactive element, two varactor diodes which are connected in opposing fashion and whose capacitance largely represents the oscillating circuit capacitance. Two feedback oscillator circuits are combined to form a push-pull circuit in that the output terminals of the oscillator circuits are connected in respect of d.c. to a reference potential by way of a central tap of the primary winding of a common output transformer. In addition, the two varactor diodes are oppositely poled and interconnected in respect of d.c.

Abstract: An exceptionally wideband, synthesizer controlled voltage controlled oscillator is disclosed which is characterized by a plurality of pin diode frequency shift networks which, when actuated shifts the frequency of the oscillator in selectable binary steps within a wide frequency range in the order of 48 MHz. Special means are included to prevent undesireable parasitic oscillation modes when such frequency shift networks are in an inactuated, switched off mode. A multiple varactor tuning circuit is provided for selecting a precise frequency within a relatively narrow frequency band on the order of 6 MHz.

Abstract: The voltage controlled oscillator (VCO) in a phase-locked loop carrier recovery circuit is provided with two control signals, one based upon a phase error between the phase modulated carrier and VCO output and the other based upon a frequency error between the phase modulated carrier and VCO output.

Abstract: A channel selection voltage generator comprises a tuning voltage generator circuit having a capacitor for supplying a tuning voltage to an electronic tuner, a first constant current source for constantly discharging the capacitor at a first constant current and a second constant current source adapted to be rendered selectively in an operative state and in an inoperative state for selectively charging the capacitor at a second constant current which is higher than the first constant current, a frequency discrimination circuit for producing a discrimination signal representative of the amount of frequency deviation when a tuning voltage deviates from a receiving frequency, a buffer circuit for producing a binary "1" level signal when the discrimination signal is higher than a predetermined value and producing a binary "0" level signal when the discrimination signal is lower than the predetermined value, and a control circuit for causing the second constant current source to assume the inoperative state when th

Abstract: A system is disclosed for synchronizing a free-swinging oscillator to a reference signal of a substantially lower frequency. A regulating circuit connects to the oscillator to control the frequency thereof. A quartz oscillator is provided for producing the reference signal. The reference signal is subsequently connected to a frequency multiplier and/or frequency divider, an amplifier and a pass band filter. An output signal from the pass band filter is fed to a harmonics mixer connected to the free-swinging oscillator and which produces a pattern of harmonics. A selective amplifier feeds an intermediate frequency obtained from the harmonics mixer to the regulator circuit. A filter also connected to the quartz oscillator produces harmonics which are also coupled to the regulating circuit. By phase or frequency comparison the regulating circuit adjusts the running frequency of the free-swinging oscillator.

Abstract: A voltage controlled oscillator has coupled thereto N capacitors in different permutation under control of an N stage binary counter and a counter drive signal enabling the generation of signals having 2.sup.N discrete frequencies. A phase locked loop is employed to stabilize each of the 2.sup.N frequencies. This loop includes a mixer coupled to a harmonic generator and the output of the oscillator. The mixer output is applied to a crystal filter whose output is phase compared with a reference signal and the resultant output is employed to stabilize the oscillator.

Abstract: An AFC voltage superimposing circuit for an electronic tuner using a plurality of varactors as a tuning element, comprising a plurality of resistors for superimposing an AFC voltage on a tuning voltage and a bypass circuit. The bypass circuit includes at least a voltage regulating diode and a diode which are connected in series so as to have the characteristic of permitting a current to flow in one direction only. When the tuning voltage exceeds a predetermined level, the voltage regulating diode comes into a conducting state, thereby increasing the AFC voltage variation superimposed on the tuning voltages, so that the interchannel deviation of AFC sensitivity may be gently compensated.

Abstract: A circuit device for generating a synchronous signal in synchronism with a steady wave component of an input signal and including a first phase-locked loop using the input signal as a reference signal, a second phase-locked loop using an output signal of a voltage controlled oscillator (VCO) of the first phase-locked loop as a reference signal, and a feedback circuit for feeding back and adding an output signal of a VCO of the second phase-locked loop to the input signal. The synchronous signal is stably obtained at the output of the VCO of the second phase-locked loop, even if the level of the steady wave component is relatively low. The level of the fed back signal may be controlled in response to the level of the steady wave component whereby the oscillation of the circuit device may be prevented.

Abstract: A phase locked loop system is described which controls and locks the frequency of a UHF transmitter to a desired frequency without the need for complex circuitry. A voltage controlled oscillator provides an output signal at the desired frequency and is controlled by an error signal from a phase detector. A harmonic resonator connected to the phase detector is tuned to a frequency which is approximately equal to the desired frequency but is displaced therefrom slightly in frequency. A reference frequency source at a subharmonic of the desired frequency is coupled to the resonator and the output signal is also coupled to the phase detector so as to generate the error signal which locks the voltage controlled oscillation precisely at the desired frequency.

Abstract: A circuit for synchronizing an oscillator keyed by a pulse is provided with a low amplitude reference oscillation. A phase shift regulating loop has a phase discriminator which is fed, on one hand, with a branched component of the oscillator output and, on the other hand, with the reference oscillation. The phase discriminator compares the phases of the two oscillators and emits a resultant regulating voltage an adjustable reactance for controlling the oscillator frequency during the leading edge of the keying pulse. A phase shift device, adjustable over 180.degree., is connected between the oscillator and the phase discriminator, the phase discriminator having a high-ohmic output which is connected, via an impedance converter, to the adjustable reactance.

Abstract: A phase detector circuit for use in a phase-lock loop is illustrated wherein a voltage pump is incorporated in the phase detector circuit so as to eliminate the utilization of a comparatively high voltage power supply which is normally required to sufficiently frequency modulate the variable frequency oscillator incorporated in most phase-lock loops.

Abstract: Frequency-modulated phase-locked loop oscillator with a special modulator bypassing the phase-locked loop to inject modulation voltage directly into the voltage-controlled oscillator of the loop to broaden the bandwidth of modulation.

Abstract: A circuit receiving a degraded synchronous pulse signal which has missing pulses and phase-shifted pulses, and producing an output signal similar to and at a constant phase angle with the input signal, in which the missing pulses have been replaced and the phase-shifted pulses shifted to the correct relative position. Provision is made for adjusting output signal frequency to long term drift in input signal frequency.

Abstract: A phase locked loop synthesizer comprising a means for controlling a tuning means, wherein a phase difference between the outputs of a reference signal oscillator and a programmable counter means is detected by a phase detector to obtain a d.c. voltage corresponding to the phase difference, an output having a prescribed frequency is generated by a voltage controlled oscillator frequency is controlled by said d.c.

Abstract: A digitally settable frequency generator comprises a master oscillator whose operating frequency f.sub.Q is variable between a normal value f.sub.Q " and a slightly lower value f.sub.Q ' = (1-p)f.sub.Q " with the aid of a normally disconnected tuning capacitor. The master oscillator works into a frequency divider of fixed step-down ratio m:1 (or 2m:1) to produce a reference frequency f.sub.B. A slave oscillator, generating an output frequency f.sub.A = gf.sub.B, is controlled by a phase-locking loop including a phase comparator to which the reference frequency f.sub.B is fed along with a like frequency obtained from output frequency f.sub.A with the aid of another divider having a digitally variable integral step-down ratio g:1. A fractional value i, which may range from 0 to 100%, is set with the aid of a numerical interpolation selector to determine the number n<m of cycles of operating frequency f.sub.Q within a cycle (or half-cycle) of reference frequency f.sub.

Abstract: A phase lock loop configuration having a voltage controlled oscillator utilized, for example, in radar systems wherein false locking is prevented and loop bandwidth is maintained substantially constant. The voltage controlled oscillator includes a cavity resonator within which is located two tuning varactor diodes, one of which is heavily coupled to the resonator and comprises a coarse tuning port and one of which is lightly coupled and comprises the fine tuning port. The configuration is such that when the loop is locked, following a sweep mode of the coarse tuning voltage, the fine tune voltage is held constant at a predetermined DC level thereby making the fine tuning sensitivity essentially constant as the coarse tuning voltage changes the frequency over the band of interest.

Abstract: To provide the required multiple channels for an aircraft communications system, a crystal controlled reference oscillator includes a tunable circuit for changing the base reference frequency provided by a crystal. The base reference frequency of the crystal controlled reference oscillator is pulled in frequency by changing the capacitance shunting the crystal. Two transistor switches change appropriate capacitors in series with the usual oscillator capacitor to obtain the capacitance values needed to pull the base reference frequency and thereby provide additional reference frequencies. The transistor switches are controlled by pilot actuated controls that operate a sliding display mark over a digital frequency indicator.

Abstract: A phase modulated wave that may have no carrier power is demodulated by a phase locked loop including a phase detector for deriving an A.C. data output signal having a magnitude and a phase indicative of the phase of the modulated wave. A feedback loop responsive to the data output signal restores power to the carrier frequency component to the loop. In one embodiment, the feedback loop includes a phase modulator responsive to the phase modulated wave and the data output signal. In a second embodiment, carrier frequency power is restored by differentiating the data output signal and supplying the differentiated signal to an input of a voltage controlled oscillator included in the phase locked loop. Preferably, the phase modulator is linear and includes a series inductance-capacitance network, wherein the capacitor is a voltage controlled varactor. To compensate for nonlinearities in the varactor reactance vs. voltage characteristic, the series circuit is shunted by a properly selected inductance.

Abstract: A television tuning system has a ramp voltage source including an electrical current source and an electrical current sink coupled through selectively operable transmission gates for varying the voltage of a tuning capacitor to control a local oscillator for tuning independent of received signal. The local oscillator signal is mixed with a received signal to produce an intermediate frequency signal which is amplified in an IF amplifier. A frequency detector is coupled to the IF amplifier and produces an error signal dependent upon the frequency difference between a reference frequency and the IF signal. An additional current source and sink are coupled to the tuning capacitor through transmission gates controlled by the error signals. Differences greater than a predetermined amount selectively activate the latter transmission gates to provide substantially constant magnitude tuning voltage corrections irrespective of the amount of the difference.

Abstract: An automatic tuning apparatus, such as an automatic channel selector as incorporated in a television receiver, comprising a tuner using a voltage controlled variable capacitance diode such that the variable capacitance thereof constitutes a portion of a tuning circuit of the tuner for changing the tuning frequency, and a solid state electrochemical potential memory devices an output voltage of which is clamped as selected by selective manual operation, the resultant voltage being applied to the capacitance diode in a reverse direction, which memory device is controlled so as to be charged or discharged in response to selective manual operation until an increased or decreased terminal voltage thereof decreases or increases the capacitance across the diode and thus increases or decreases the tuning frequency of the tuner and a particular frequency is tuned.

Abstract: An automatic tuning apparatus, such as an automatic channel selector as incorporated in a television receiver, comprising a tuner using a voltage controlled variable capacitance diode such that the variable capacitance thereof constitutes a portion of a tuning circuit of the tuner for changing the tuning frequency thereof, and a solid state electrochemical potential memory device, an output voltage of which is applied to the capacitance diode in a reverse direction, which memory device is controlled so as to be charged or discharged in response to selective manual operation until an increased or decreased terminal voltage thereof decreases or increases, respectively the capacitance across the diode and thus increases or decreases, respectively the tuning frequency of the tuner and a particular frequency is tuned. An intermediate frequency output, obtained as a result of tuning, is used to disable the abovementioned charging or discharging operation of the potential memory device.

Abstract: A local oscillation circuit for a tuner having a reduced inter-channel deviation in AFC sensitivity. The local oscillation circuit comprises a resonance circuit capable of varying a tuning frequency by means of a variable capacitive element additionally provided with a variable capacitive diode which is applied with a control voltage in dependence upon variation in the frequency detected from the output signal of the tuner, thereby to effect an automatic frequency control. A single variable capacitive diode is coupled to the variable capacitive element of the resonance circuit in a parallel and a series connections.

Abstract: An AFC tuning circuit is provided having a tuning capacitance in parallel with a series connection of a varactor and an inductance coil. A series-connected switch and capacitor are connected in parallel with the varactor. Another switch is connected in parallel with a portion of the inductance coil. Both switches are open for a lower frequency band and closed for a higher frequency band to provide a relatively uniform AFC circuit sensitivity for both frequency bands.