Abstract: One embodiment of the present invention relates to a system that provides a high frequency local oscillator (LO) signal. The system comprises a first LO that generates a first frequency LO signal component, a mixer that generates a difference signal from the first frequency LO signal component and a second frequency LO signal component, and a second LO that generates the second frequency LO signal component that is a harmonic of the difference signal.

Abstract: A dual conversion, noise resistant, digitally-controlled mm-wave frequency synthesizer for generating rapidly-tunable RF signals. The prime signal-generation source is a 3.0-3.2 GHz low noise wide band voltage controlled oscillator (“vco”). The oscillator includes a buried stripline hairpin resonator having dual-tuning circuits to increase bandwidth coverage and unique bias circuitry to improve phase noise. The oscillator frequency is multiplied by a factor of two, yielding a 6.0-6.4 GHz signal that is mixed with a fixed locally generated carrier of 3900 MHz, the output of which represents the first Intermediate Frequency (IF). This IF is then mixed with 1950 MHz (3900 MHz divided by two), yielding a second IF that covers the 188 to 550 MHz range. The 2nd IF is divided down and phase locked to an external reference using a commercially available chip set. The 6.0-6.4 phase locked signal is then re-mixed with the 3.0-3.2 GHz output form the oscillator, thereby yielding a 9.0-9.6 GHz signal. The 9.

Abstract: The frequencies of N oscillators are summed to provide a signal generator output signal. Because the phase noise power spectral densities of the oscillators add as power, the frequency summed output exhibits a noise degradation over a single oscillator of only 10 log(N). The signal generator is implemented to assure independence of the oscillator noise contributions, with phase locking the oscillators to a common frequency for ease of spurious signal control.

Abstract: A microwave digital communication system PSK-modulates a microwave carrier by using a main signal and, further, frequency-modulates it by using a service channel (SC) signal for monitoring and controlling the system. An intermediate relay station employing a space diversity reception system converts a received microwave into an intermediate frequency (IF) to extract the SC signal, and converts the IF signal into a microwave to transmit, thus performing heterodyne relay. The intermediate relay station generates a phase error signal corresponding to the frequency deviation of the IF received signal, by using the IF received signal and an IF reference signal having a fixed frequency equal to the carrier frequency of the IF received signal, and extracts the phase error signal as an SC signal. The SC signal is inputted as a control signal to a VCO for generating a receiving-side local oscillation signal so that the frequency of that follows the variation of the frequency deviation of the received microwave.

Abstract: For use with a quartz angular rate sensor, a frequency and phase-locked synthesizer recovers a reference signal virtually free of phase noise, and generates a quadrature-phase reference signal for complex demodulation of the angular rate signal. The synthesizer also ensures a precisely adjusted phase shift of approximately zero across the drive tines of the sensor. Moreover, the digital synthesizer provides a precise numerical indication of the drive frequency, which can be used for compensation and automatic tuning of filters, such as a tracking filter, a filter in an automatic gain control, and notch filters in the phase and/or frequency detectors in the digital synthesizer. The tracking filter is used as a pre-filter for the synthesizer, and is responsive to a passband-width control signal generated from the magnitude of the frequency and phase error signal controlling the frequency generated by the synthesizer.

Abstract: A frequency synthesizer in which a PLL synthesizer 50 generates signals of frequency steps of an integer times a target frequency step. A base band generator 2 digitally generates sine wave signal components of the target frequency step. The outputs from the PLL synthesizer 50 and the base band generator 2 are cross-modulated by use of a quadrature modulator 1 to change the frequency of the output signals with a change step of the base band generator 2.

Abstract: Power is provided to the stator windings of an AC induction machine which includes a component at the fundamental drive frequency for the machine and a superimposed signal component which is at a substantially higher frequency than the drive power. The fundamental drive power is provided at a level which results in saturation in the stator which follows the magnetic flux vector. The stator response at the signal frequency is then detected to provide a correlation between the response at the signal frequency and the magnetic flux vector position. The detection of the response at the signal frequency is preferably carried out by a heterodyne detection process, by mixing signals at the signal frequency with the measured stator currents, and filtering the mixed signals to isolate the signal indicative of the flux vector position.

Abstract: A frequency synthesizer includes three subfrequency synthesizers: a first synthesizer generating a first subfrequency varying in units of a frequency step, a second synthesizer generating a second subfrequency varying in units of a frequency step being N times the first frequency step, and a third synthesizer generating a third subfrequency varying in units of the first frequency step. One output signal is obtained by mixing the first subfrequency and the second subfrequency. A second output signal is obtained by mixing the second subfrequency and the third subfrequency.

Abstract: A multiple feedback loop frequency synthesizer, having a first and a second feedback loop, each fed by one of a pair of reference frequency signals having a frequency separation equal to the desired frequency separation of the output signals provided by the synthesizer. The frequency of each of such reference frequency signals is greater than the desired frequency separation of the output signals provided by the synthesizer. With such arrangement, because the bandwidth of each of the feedback loops must be less than the frequency of the reference frequency signal fed to such loop, achievement of frequency separation less than the frequency of either one of the reference frequencies enables each of the feedback loops to have increased bandwidth and hence reduced frequency switching times and increased noise suppression.

Abstract: A Frequency synthesis stage comprises two phase locked loops. The first (O.sub.1, D.sub.1, M, CP.sub.1, D.sub.2) divides the frequency Fo+.DELTA. derived from preceding stages by N/Q, N being a variable integer, and adds to the result a standard frequency P which is in a fixed ratio with a value representative of large frequency steps so as to give an intermediate frequency F.sub.A, while the second (O.sub.2, M.sub.0, M.sub.1, CP.sub.2 D.sub.3) multiplies F.sub.A by NQ/r. P and Q are selected so that the product PQ is approximately equal to the mean of the limit values desired for the output frequency.

Abstract: A phase-locked loop is constituted by a controllable oscillator coupled through a phase detection arrangement and a low-pass filter to receive an input carrier applied to a signal input of the phase detection arrangement. In order to decrease the phase synchronization between a carrier locally generated in the loop and an input carrier, an unwanted DC offset generated during phase detection is reduced. The phase detection arrangement has first, second and third cascade-coupled mixer stages. An auxiliary mixing signal is applied from a signal generator to the first and third mixer stages. An input of one of the first and second mixer stages is coupled to the signal input of the phase detection arrangement and an input of the other of the two last-mentioned stages is coupled to an output of the controllable oscillator. The low-pass filter has a cut-off frequency lower than the fundamental frequency of the auxiliary mixing signal, and the fundamental frequency is lower than the frequency of the input carrier.

Abstract: A frequency synthesizing apparatus of the closed-loop design employing a first frequency mixing means to provide a continuous constant increment frequency coverage over a given output signal frequency range. The first frequency mixing means is responsive to the output signal and a first reference signal to provide a first difference signal both when the output signal frequency is higher than and lower than the first reference signal frequency. A frequency comparison means is responsive to the first difference signal and to an input signal, the input signal being continuously variable over a given input frequency range, to provide a first error signal for controlling the output frequency and stabilizing the closed loop. The first reference signal is comprising of a plurality of predetermined, selectable frequencies provided by a phase-locked loop employing a second frequency mixing means.

Abstract: A radio receiver from antenna to detector designed to be realized substantially on an integrated-circuit chip comprises a single tunable oscillator and a plurality of mixers. An input signal from an antenna is connected as an input to a first mixer and mixed with a signal derived from the oscillator. The signal may be taken directly, may be multiplied to a desired level or may be divided to a desired level. A particular output from the first mixer is selected by a first tunable filter. The output of the first tunable filter is taken as an input to a second mixer where it is mixed with a second signal derived from the oscillator. The process of mixing and application of the mixed signal to a tunable filter to select a desired frequency is continued as needed until the signal is reduced to a desired intermediate frequency range where it is amplified as needed to a level sufficient to drive a discriminator.

Abstract: Two collocated, weakly coupled probes, on loop and one dipole, detect the magnetic and electric fields inside a maser cavity. Signals from the probes are compared in phase, and the signal output from the phase detector is applied to a varactor, the reactance of which is coupled into the cavity by a microwave coupler. Alternatively, the varactor may be placed inside the cavity. Any deviation of phase from 90.degree. as detected by the phase detector will then produce an error signal that will change the reactance coupled into the resonant cavity to change its reactance, and thus correct its resonance frequency. An alternative to using two probes is to use a single disk probe oriented to detect both the magnetic and electric fields, and thus provide the error signal directly.

Abstract: A signal processor circuit including a plurality of similar cascaded stages, each of which is capable of locking onto and tracking a different frequency of a multiple-frequency composite signal applied to the processor. Each of the stages may comprise a frequency locked loop plus a variable frequency stop, wherein the tuning of the variable frequency stop tracks the output of the frequency locked loop. The variable frequency stop circuit passes the non-locked components to the next similar stage which locks onto one of the remaining components.

Abstract: A wide band oscillator with phase lock loop is controlled by signals from an 40 MHz harmonics generator combined with the output of another phase lock loop controlled oscillator whose selectible outputs vary in MHz steps with a total range of 39 MHz. The phase lock loop of the wide band oscillator is additionally controlled by a d/a converter and by another phase lock loop controlled oscillator whose selectible outputs vary in one KHz steps. Each of these phase lock loops is digitally controlled from the input frequency selection and again therefrom via a digital-to-analog converter. The output of the wide band oscillator is combined with the output of a narrow band oscillator which may be FM modulated. Alternatively, an output amplifier for the combination difference frequency may be AM modulated.

Abstract: A frequency and phase lock loop is disclosed in which AFC and phase locking functions are completely separated thus permitting signal acquisition range and closed loop bandwidth parameters to be independently established. Interference between phase lock loop (PLL) and automatic frequency control (AFC) signals resulting in the loss of a beat frequency signal for matching VCO and reference signal frequencies is eliminated thus affording enhanced PLL frequency pull-in range.

Abstract: The invention provides a double superheterodyne receiver having the usual first and second frequency changers associated with first and second local oscillators. The second local oscillator is provided as a voltage controlled oscillator and means are provided for determining the difference frequency between the two local oscillators to produce a control signal which is applied to the second local oscillator to tend to maintain the difference frequency constant.

Abstract: A radio receiver comprises a frequency conversion circuit connected between a frequency-variable local oscillator and a divide-by-N programmable counter incorporated in a phase locked loop frequency synthesizer and adapted to continuously change the frequency to be divided by the programmable counter. Owing to the frequency conversion circuit, the local oscillator frequency is permitted to continuously change in the locked state of the phase locked loop so that the intermediate frequency offset adjustment of receivers, that is, the adjustment of the intermediate frequency of each receiver to the center frequency of an intermediate frequency filter used in the receiver can be made easily, and that a reception of such a broadcast station as having a carrier frequency which is not an integral multiple of a channel spacing frequency also can be made.

Abstract: The use of a digital frequency translator, using pulse snatching techniques, for multiplying the output frequency of a precise and accurate frequency synthesizer by a preselected certain numerical fraction permits the frequency synthesizer to be referred to a molecular clock with only a single VCXO phase lock loop.

Abstract: A microwave frequency synthesizer utilizing a phase locked loop for generating a wide range of microwave frequencies in response to a control signal, in combination with a network including a plurality of distinct frequency local oscillators that are appropriately selectable for mixing with the signal output of the phase locked loop for translating it into a desired range, thereby expanding the effective frequency range of the phase locked loop. The combination provides a stable source of microwave frequency signals over a wide frequency range. The combination allows a simple, low cost circuit implementation and may be switched between output frequencies at a very fast speed.

Abstract: The output of a VCO, a referenced frequency signal and an offset frequency signal are mixed to provide a control signal for the VCO and a double offset frequency signal which is mixed with an output of the offset frequency source to provide a DC component having a positive polarity if the signals are inphase and the VCO is locked on one sideband and a negative polarity if the signals are out of phase and the VCO is locked on the other sideband. A sweep signal is activated and applied to the VCO in response to the VCO being locked onto the wrong sideband.

Abstract: A comparator-discriminator is provided, suitable for use with a phaselock control system of a frequency synthesizer, to permit automatic tuning of a variable oscillator to a selected frequency lying within a frequency band for which a phaselock may occur. This system permits the frequency of the variable oscillator to lock-on to an arbitrary value in the range other than the preselected value, at which time the phaselock is broken by an injected signal, thereby permitting the shifting of the oscillator frequency to a value lying closer to the selected frequency value. Upon achievement of phaselock to the selected frequency, in a slightly more elaborate embodiment, the injected signal is inhibited and no further breaking of phaselock can occur.

Abstract: A system is disclosed for generating a plurality of preselected frequencies in a radio frequency device such as a receiver, transmitter or transceiver. It comprises means for generating a first reference signal having a predetermined frequency and means, including at least two voltage controlled oscillators (VCO), a mixer, a programmable frequency divider, and a switch, for generating a second reference signal, with the mixer being coupled to the first reference signal generating means and being selectively coupled on one of the VCO's by the switch to generate an output signal having a frequency corresponding to the difference between the frequency of said first reference signal and the frequency of the selected variable-frequency oscillator.

Abstract: A system is disclosed for generating a plurality of preselected frequencies in a radio frequency device such as a receiver, transmitter or transceiver. It comprises two crystal-controlled reference signal oscillators. First and second controllable variable-frequency oscillators (VCO's), first and second mixers, and a programmable frequency divider, together generate first and second output signals, with the first mixer being coupled to the first crystal oscillator and to the first VCO to generate the first output signal having a frequency corresponding to the difference between the frequency of the first reference signal and that of the first VCO. The second mixer is coupled to the second crystal oscillator and to the second VCO to generate the second output signal which has a frequency corresponding to the difference between the frequency of the second reference signal and the frequency of the second VCO.

Abstract: An automatic phase and frequency control system includes a pair of multipliers coupled to a source of input signal. A voltage controlled oscillator is also coupled to each of the multipliers. Means are provided to phase shift the oscillator signal at one multiplier such that quadrature beat signals are produced. The output of one of the multipliers is coupled directly to a third multiplier while the output of the other is coupled to a low pass filter. The filtered signal is amplitude limited and applied to the third multiplier. A second low pass filter couples the output of the third multiplier to the frequency control input of the voltage controlled oscillator.

Abstract: Apparatus and method for providing an automatic frequency tuning system capable of supplying a local oscillator signal with a preselected frequency. The frequency of an output signal of the local oscillator is electronically varied across a frequency region which includes the preselected frequency. The output signal of the local oscillator is combined with the output signal of a reference signal generator. After the combination of the local oscillator signal with the reference oscillator signal produces a preestablished condition which is the result of the local oscillator signal attaining the preselected frequency, the frequency of the local oscillator signal is held constant. The local oscillator signal is thereafter compared to the reference oscillation signal and a change in the local oscillator signal frequency is corrected by means of an automatic frequency control feedback loop containing a discriminator circuit.BACKGROUND OF THE INVENTION1.