Showing papers on "Frequency multiplier published in 1972"

Surveillance system and method utilizing both electrostatic and electromagnetic fields

Abstract: A microwave signal generator projects an electromagnetic wave into a space under surveillance to establish a first field. A pulse or frequency modulated low frequency generator is used to apply a voltage to a discontinuous conductor for establishing a second field, electrostatic in nature, throughout the space. Presence in the space of a miniature passive electromagnetic wave receptor-reradiator in the form of a semiconductive diode connected to a dipole antenna causes the reradiation of the low frequency component modulated on the microwave component as a carrier. The front end of a receiver system is tuned to the microwave frequency and feeds a suitable detector circuit responsive to the low frequency signal. A coincidence circuit energizes an alarm circuit whenever the detected signal coincides with the original modulation envelope being applied to the low frequency generator.

Frequency modulator-variable frequency generator

Abstract: A frequency modulator/variable frequency source employs an electronically programmable divider in the feedback path of a phase locked loop. The phase locked loop is stabilized by the output of a fixed frequency oscillator. The effective divider modulus is directly determined by a variable duty cycle signal which alternately switches the divider between two characteristic count capacities with relative dwell periods determined by a modulating potential.

Crystal controlled frequency discriminator

Abstract: A frequency discriminator has an accurately controlled delay time for delaying a frequency modulated signal for a fixed time interval such that the frequency deviation of the input signal is converted into a related phase deviation. An EXCLUSIVE OR circuit compares the input signal with the delayed input signal to produce an output signal of constant amplitude and duration pulses having a pulse repetition rate double that of the carrier frequency of the input signal. The fixed delay is provided by a multistage shift register that is clocked by a crystal controlled oscillator.

Automatic frequency control system for driving a linear accelerator

Abstract: An automatic frequency control system is described for maintaining the drive frequency applied to a linear accelerator to produce maximum particle output from the accelerator. The particle output amplitude is measured and the frequency of the radio frequency source powering the linear accelerator is adjusted to maximize particle output amplitude.

Time division interpolator

Abstract: An electronic circuit is disclosed for generating an output signal having a frequency which is a selected multiple of a variable input signal frequency. To obtain the desired multiplication, a relatively high clock signal frequency is divided by a number which corresponds to the selected multiple to produce a second signal having a lower frequency than the clock signal frequency. The individual pulses of the lower frequency signal are counted during the time interval between two consecutive input signal pulses to generate a second, variable, number which is then used to divide the clock signal frequency in the time period immediately following the occurrence of the second of the two consecutive input signal pulses. The resulting output signal therefore occurs at a frequency which is equal to the frequency of the input signal multiplied by the desired multiplicative factor.

Accurate and stable encoding with low cost circuit elements

Abstract: This accurate and stable analog to digital conversion system and circuits useful therewith is based upon selective counting of high frequency electrical signal oscillations generated by a phase locked frequency multiplication network The network contains only low cost components Accuracy and stability derive from maintenance of predetermined phase locked relationship between the signal derived through frequency division of the network output signal and a cyclic reference signal which is also the reference for gating the encoding counts (ie the reference for measurement of the analog parameter which is to be encoded) The network output frequency is a harmonic of the frequency of the reference signal Feedback phase control is developed through interaction of the frequency divided network output with the reference signal in a phase comparator circuit A novel circuit arrangement for generating the reference signal in the form of ramp oscillations is also disclosed

Incremental phase shift frequency synthesizer

Abstract: Apparatus for synthesizing an adjusted reference signal at a frequency that is controllable to a prescribed value performs the programmed addition (or subtraction) of sequential incrementation of phase shift to the reference signal output of an undisturbed oscillator that has a characteristic frequency of oscillation that is accurately predictable for a significant time period into the future. Purposes of the proposed apparatus include (a) the generation and maintaining of small offsets in the frequency of the adjusted output reference signal relative to the nominal or actual frequency of the oscillator, (b) the compensation for the time dependent predictable drift of the source oscillator to maintain the adjusted output signal at the desired frequency even though the source oscillator frequency changes, (c) the operation of precise time and frequency systems with complete coherency between the modulation representing timing and the RF carrier representing frequency, and (d) the ability to calibrate, adjust, and normalize the timing of a clock system operating from the adjusted reference signal both as to location of its epoch(s) and its scale relative to an accepted system primary standard of time.

The power spectrum and its importance in precise frequency measurements

Abstract: S>The power spectral density functions of a frequency multiplier chain, driven by several different crystal oscillators, were obtained by comparing the output with a second chain that was stabilized with an ammonia maser. The frequency of the maser stabilized chain was demonstrated to be relatively fixed; the power spectrum of the other chain was determined by two different methods. The results are compared. Possible errors and uncertainties introduced by the methods are discussed. An analysis is made that relates the instantaneous frequency fluctuations of a signal with the power spectral density function. Analysis predicts that when frequency modulation occurs in the first stages of frequency multiplication or in the primary frequency oscillator, the output power spectrum is, in general, not symmetrical. Furthermore, the sidebands are increased in intensity by the multiplication process. This is, in fact, observed to be the case. It is shown that a frequency counter will measure the frequency of the center of gravity of the power spectrum. If signals having a complex power spectrum are used in precise frequency measurements, errors may result. (auth)

High-frequency transistor frequency multipliers and power amplifiers

Abstract: A design theory for transistor frequency multipliers and power amplifiers is presented. The analytical approach is dependent upon two main assumptions, 1) that intrinsic base region behavior may be represented by a simple charge-control form model, and 2) that depletion layer charging current effects may be neglected initially and included when necessary as a perturbation of the analysis. The intrinsic base region is represented by a `partial sinusoid' model of base current flow during the conduction period of the emitter junction. This model is a simple representation of a complex process and is chosen on the basis of adequacy of characterization of the response of actual vices under practical operating conditions, together with a simple analytical form. The analysis of transistor frequency multiplier and power amplifier operation is developed in terms of the model and design relationships are presented. Results showing good agreement between the theory and measured data are given.

An Automatic Control Scheme of HVDC Transmission Using Digital Techniques Part I Principles of Operation

Abstract: The requirements of HVdc converter control are achieved by dicrital techniques with minimisation of circuit complexity. Feed-back control is applied to modification of the counting of clock pulses derived from the ac system by a phase-locked frequency multiplier. Symmetry of the derived firinc, oulses can be retained for all modes of operation with smooth transition from full rectification to full inversion.

Frequency deviation monitor and measuring device

Abstract: A frequency deviation monitor for measuring instantaneous variations of an input signal from a reference frequency, including an input circuit developing an intermediate signal of constant amplitude, a phase-shifting circuit that shifts the signal in phase by an amount and in a direction representative of deviations of the signal from a given reference frequency, and a key signal generator that develops short-duration key signal pulses at the input signal frequency. The signals from the phaseshifting circuit and the key signal generator are applied to a sampling demodulator that develops an output signal having an amplitude and polarity indicative of the deviation of the input signal fro m the reference frequency.

Power supply circuit to simultaneously vary frequency and amplitude in a motor speed control

Abstract: A multiple pulse pulse-width modulation system is disclosed for controlling the speed of a standard three-phase induction motor or synchronous motor. An oscillator provides a clock signal which is divided down by a counting chain of two flip-flops to provide a first signal which is half the frequency of the clock signal and a second signal which is a quarter of the frequency of the clock signal. The first signal is integrated over the half cycles thereof while the second signal is applied to a digital wave form synthesizer which includes shift register stages and weighting resistors. The wave form synthesizer provides three output signals which are a stepwise approximation to a three-phase sine wave. Each of the three phases of the three-phase sine wave are applied to a differential comparator for comparison with the output of the integrator. The oscillator is variable in frequency so that the frequency of the three-phase sine wave and the amplitude of the integrator output can be varied thereby.

Wide band phase-coherent self-calibrating translation loop

Abstract: A translation loop with a voltage controlled oscillator (VCO) for generating a plurality of discrete frequencies that are unambiguously selected above or below a reference frequency by calibrating the VCO to the reference frequency without the presence of an offset frequency, a timed gate control subsequently gating the offset frequency for mixing in the loop. A phase detected error in the mixed signals controls the VCO to alter its frequency from the reference frequency to the frequency corresponding to the sum or difference frequency by a control sweep voltage positive or negative going to correspondingly increase or lower the VCO frequency.

High power modulator-dimodulator amplifier circuit

Abstract: For use in high power applications, an apparatus for amplifying input signals having a predetermined upper frequency limit and employing a pair of phase modulated auxiliary carrier frequency sources having the same average frequency value being greater than the upper frequency limit of the input signals. The auxiliary carrier frequency sources are controlled by phase control means to have opposing phase displacements which are related to the momentary values of the amplified input signals. The outputs of said auxiliary carrier frequency sources are summed preferably by transformer means, the summation renders a signal of said average frequency and of modulated amplitude. This sum signal is demodulated, e.g., by fullwave rectification, and filtered to produce an amplified input signal being the amplifier output. Thus said carrier frequencies are performing an auxiliary function in amplifying the input signals and substantially do not appear in the amplifier output.

Adjustable frequency pulse generator

Abstract: In a pulse generator such as may be used in crystal controlled electronic time pieces, comprising an oscillator circuit coupled to a chain of successive frequency divider stages, to obtain output pulses substantially lower in frequency than the oscillator frequency, means are provided to periodically and temporarily bypass one of the frequency divider stages. The frequency correction made by such bypass arrangement may serve to correct for the error in oscillation frequency of a crystal controlling the oscillator circuit when such crystal is purposely ground to oscillate at slightly below a desired precise rate.

Electric power amplification at low frequencies

Abstract: A modulator-demodulator amplifier having high power gain at frequencies from D.C to 200 Hz. The low frequency signal to be amplified is full wave rectified (producing half cycles at twice the low frequency) and subsequently used to modulate a higher frequency signal which falls in the band pass of a conventional power amplifier. After amplification, the modulated signal is rectified so as to produce alternate positive and negative half cycles of the original low frequency. The signal is then fed to a low pass filter which retrieves the envelope of the modulated signal which constitutes an amplified version of the low frequency signal. This concept is also applicable to higher frequency amplification, i.e., radio and video frequency amplifiers, to extend their response to include the audio frequency range.

Compressing and/or expanding system comprising fixed and variable frequency characteristic changing circuits

Abstract: A compressing and/or expanding circuit comprises a first circuit consisting of a frequency characteristic changing circuit having a specific fixed frequency-response characteristic and a frequency characteristic changing circuit including a control element and having a frequency response characteristic variable between a characteristic complementary with said specific fixed frequency response characteristic and a flat characteristic, an amplifier connected in series with the first circuit, and a second circuit provided in a feedback loop associated with the amplifier, which has the same circuit structure as the first circuit. In the compressing circuit, the first circuit, applied with a control signal voltage in response to the level of an input signal, causes its frequency response to vary, whereas the second circuit, applied with a constant voltage, manifests a flat frequency response characteristic. In the expanding circuit, the first circuit, applied with a constant voltage, manifests a flat frequency response characteristic, whereas the second circuit, applied with a control signal voltage corresponding to the signal level, causes its frequency response to vary.

Locking system using radio wave

Abstract: A locking system using radio waves. The system is made up of a transmitting means having a low frequency oscillation circuit with a mechanical filter circuit and an instantaneous starting circuit, an amplification circuit, a half-wave rectifying and a rectangular wave rectifying circuit for a low frequency generated by said low frequency oscillation circuit, and a high frequency oscillation circuit operated interruptedly by a rectified rectangular wave from said half-wave rectifying and rectangular wave rectifying circuit. A receiving means receives electric wave energy radiated from said transmitting means, said receiving means including a frequency detection circuit with a filter circuit to permit a narrow range of high frequency and low frequency to pass, and a mechanical filter circuit having a peak value forming circuit for amplifying and attenuating a peak value of the detected output from said frequency detection circuit to make the value of said detected output constant. The lastmentioned mechanical filter circuit further has an integral circuit. The output signal for operating a locking mechanism is obtained through a rectifying circuit for the output of the lastmentioned filter circuit and a DC amplication circuit with a delay circuit.

Parametric device for multiplying frequencies

Abstract: The present invention relates to a device energized by two input frequencies which furnishes at the output a frequency whose numeric value is equal to the product of the numeric values of the input frequencies. It works by cooperation between a phase discriminator, a VCO-type oscillator and a variable-sequence divider which is automatically set in accordance with the state of an electronic counter which is excited by one of the two frequencies. This counter which is synchronized with a time base operates like an electronic frequency-meter adjusting the variable-sequence divider at the end of each counting interval. The basic multiplier circuit is also used to provide modified embodiments, one of which produces the square of an input frequency, another the inverse of an input frequency, the third the square root of an input frequency. Different applications of these circuits are presented for different problems of measuring physical quantities.

Electronic signal multiplier

Abstract: A frequency multiplier for frequency variable electronic signals for use with a fluid flow measuring system. The generally sinusoidal output signal from a fluid flowmeter is converted to a square wave signal of the same frequency. The square wave signal is integrated to form a triangular wave signal variable in both amplitude and frequency with the frequency of the square wave signal. The peak-to-peak amplitude of the triangular wave signal is then adjusted to a predetermined value irrespective of input signal amplitude or frequency in an automatic gain control circuit, and the frequency of the triangular wave is thereafter doubled to the desired value by cascaded doubling stages. Each doubling stage includes a two-channel half-wave rectifier, means for shifting the bias of the rectified waves, and means for both inverting one of the bias shifted waves for combining the inverted wave with the other bias shifted wave to center the combined wave about a zero volt axis. In an alternative embodiment, with the output signal from the flowmeter in the form of a series of constant amplitude, constant width, variable recurrence rate pulses, a reversible ramp generator is used to form a triangular wave signal having an amplitude and a frequency variable with the frequency of pulse recurrence. The peak-to-peak amplitude of this triangular wave is likewise adjusted to a predetermined constant value and the frequency multiplied in cascaded doubling stages as described above.

Waveguide component comprising non linear elements

Abstract: A waveguide component for use in microwave range or in quasimillimeter wave range such as, for instance, a frequency multiplier or a frequency down converter. The waveguide component comprises a strip line element functioning as an antenna for resonating at least two electromagnetic waves having different frequencies and a semiconductor element of which one end is connected to the strip line. Both the strip line and the semiconductor element are provided onto a dielectric base plate by means of printing circuit technique. The dielectric base plate is mounted in a waveguide in a manner that the strip line element extends parallel to a high frequency electric field in the waveguide. The waveguide component having above construction is able to be miniaturized by the elimination of the conventional tuning circuit elements and due to its improved semiconductor mounting it is suitable to be used in quasi-millimeter wave range.

Electronic balance for measuring masses or forces

Abstract: A balance for measuring masses and forces comprising a phase-locked frequency multiplier which multiplies the string frequency F1 that is raised by the process of measurement with a predetermined fixed factor in such manner that the multiplied frequency retains a constant phase relationship with the original frequency and wherein the number of full cycles of the multiplied frequency F1 is counted for a period of time corresponding to a given number of full cycles of the frequency F2, which frequency is reduced by the measuring process.

Signal frequency detection circuit

Abstract: A circuit having a plurality of separate trigger circuits each being provided with the components of the signal which fall within a separate frequency band. Each trigger circuit is designed to trigger only when a signal occurs within the associated frequency band. The outputs of the trigger circuits drive an ''''OR'''' gate which in turn drives a counter. The circuit is particularly adapted for use in noisy applications where the signal level varies with frequency, such as for example with a flow meter.

Presettable frequency divider

Abstract: A frequency divider including two down-counters having common input and output terminals, an input signal steering device, and a presettable logic circuit. The latter includes a series of switches which are preset to establish a particular divisor by establishing an initial count in the down-counters. The steering device includes a pair of gates which steers the input signal to one of the two down-counters which in turn counts the cycles of the input signals. After counting down to zero, the down-counter generates an input signal which is used by: (1) the steering device, to transfer the input signal to the other down-counter; (2) the presettable logic circuit, to reestablish the count in the down-counters, and the output terminal, to generate the frequency divided output.

Crystal controlled, frequency modulated transmitter

Abstract: A frequency modulated transmitter for use at frequencies from 25 to 54 MHz is disclosed. The crystals in the transmitter oscillate at their fundamental frequency, and this frequency is divided by four to produce a lower frequency which is then modulated. This lower modulated carrier frequency is then multiplied by 24 to produce an output frequency in the desired range.

Multiple carrier frequency modulated signal generating apparatus

Abstract: Signal generator for use in testing FM communication receivers including a triggered free-running multivibrator which may be synchronized to operate at a frequency equal to the spacing between adjacent channels of the FM receiver An audio oscillator modulates the output of the multivibrator which output is applied to a step recovery diode The output of the step recovery diode is a plurality of harmonics of the frequency of the multivibrator each frequency modulated at the frequency of the audio oscillator

Frequency multiplier circuit

Abstract: Apparatus for multiplying an input frequency by a number A/B where A and B are integers and A > B. During one period of the input frequency, fin , pulses at a rate fo/A are accumulated and held. Pulses at a rate fo/B are continuously counted and for each P pulses of said latter pulses an output pulse is generated. Since P is the number of fo/A rate pulses occurring during one period of fin, the output pulse rate is fin x A/B. Additional means are provided for averaging the period of fin by counting the fo/A rate pulses for a multiple of periods of fin and obtaining the number P occurring during a single period by effectively dividing the accumulated pulses by said multiple.

Technique for extending the frequency range of digital dividers

Abstract: A technique for extending the frequency range of a presettable digital divider. The conventional digital divider consists of several counter stages with the count of each stage compared to a preselected number. When the counts for all stages are equal to the preselected numbers, an output pulse is generated and all stages are reset. For high input frequencies, the least significant stage of the divider has to be reset in a very short time. This limits the frequency that can be handled by the conventional digital divider. This invention provides a technique in which the second least significant and higher stages are reset and the least significant stage is permitted to free-run. Hence, the time in which the reset operation can be performed is increased thereby extending the frequency range of the divider.

Frequency-selective calibrated amplitude-measuring system

Abstract: An incoming signal voltage of frequency fe, whose amplitude is to be measured, is additively heterodyned in a first mixer with a locally generated variable test frequency ft to provide a first beat frequency fi1 fe + ft clearing a first filter with a pass band including that beat frequency. In a second mixer, preceding a second filter with a narrow pass band centered on a second beat frequency fi2, the first beat frequency fi1 is subtractively heterodyned with a locally generated ancillary frequency fc of magnitude fi1 - fi2 to provide the frequency fi2 which passes the second filter and reaches an amplitude indicator through an adjustable amplifier or attenuator. In a calibrating position, a fixed reference frequency fo fi2 from a local oscillator is substituted for the input frequency fe whereas the test frequency ft is replaced by the ancillary frequency fc in the first mixer.

Voltage tunable frequency threshold circuit

Abstract: A circuit having a voltage tunable threshold generates an output signal indicative of whether an input signal frequency is above or below the threshold frequency. A ramping signal is started and terminated at predetermined points on the input signal frequency waveform. The ramp amplitude at termination is compared against a d.c. reference voltage proportional to the threshold frequency to indicate whether the input signal frequency is above or below the threshold. The threshold circuit is also shown used in an adaptive frequency shift keying demodulator. The demodulator threshold analyzes a received reference frequency and generates a d.c. reference voltage level for the frequency threshold circuit proportional to the reference frequency.