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Showing papers on "Pulse-frequency modulation published in 1974"


Journal ArticleDOI
TL;DR: The coding of small rapid changes in amplitude of pure tones in single units in the cochlear nucleus of the rat was studied using sinusoidally amplitude-modulated tones to study the reproduction of the amplitude modulation of the sound in the discharge frequency of the units as a function of sound intensity.

99 citations


Journal ArticleDOI
TL;DR: A class of adaptive schemes for delta modulation is considered whereby the decision about step size is a function of the present and the last k symbols, and results indicate that other criteria functions may achieve still higher values of SNR.
Abstract: A class of adaptive schemes for delta modulation is considered whereby the decision about step size is a function of the present and the last k symbols. Such schemes are studied by computer simulations using speech-like signals through evaluation of SNR. Occasional large overshoots appear in the reconstructed signal after the integrater, and to avoid such events it is proposed to store a few signal samples and decide on the proper bit stream taking into account the adaptive logic. Two quadratic criteria have been tried, and improvements of a few decibels have been established with six stored signal samples and a sampling rate of 48 and 24 kHz. Results indicate that other criteria functions may achieve still higher values of SNR.

53 citations


Patent
23 Dec 1974
TL;DR: In this paper, a grain loss monitor for a combine harvester derives a grain rate signal in accordance with the number of grains impinging on a transducer and a ground speed signal proportional to the ground speed of the combine and divides the former by the latter to derive an analog of grain loss per unit area.
Abstract: A grain loss monitor for a combine harvester derives a grain loss rate signal in accordance with the number of grains impinging on a transducer and a ground speed signal proportional to the ground speed of the combine and divides the former by the latter to derive an analog of grain loss per unit area which is independent of time. The preferred embodiment includes a one-shot multivibrator which is triggered to its unstable state to generate a fixed width pulse each time a grain kernel strikes the transducer, a tachometer coupled to the combine wheels and a period timed integrator triggered by tachometer pulses for deriving a unidirectional ground speed voltage inversely proportional to frequency of the tachometer pulses, a pulse frequency modulation chopper circuit turned on and off by the fixed width one-shot pulses and having its peak voltage controlled by the unidirectional ground speed signal for accomplishing division of grain loss rate by combine ground speed, and an averaging circuit for determining the average voltage of the chopper output pulses as an analog of grain loss per unit area.

46 citations


Patent
Harold Seidel1
03 Sep 1974
TL;DR: In this paper, the phase modulation distortion due to phase modulation error in an interferometer type modulator is minimized by extracting a portion of the phase modulated carrier frequency signals in the two branches of the interferometers and sensing the resulting amplitude modulation in an auxiliary Interferometer circuit.
Abstract: Modulation distortion due to phase modulation error in an interferometer type modulator is minimized by extracting a portion of the phase modulated carrier frequency signals in the two branches of the interferometer and sensing the resulting amplitude modulation in an auxiliary interferometer circuit. The modulation signal is compared with the input modulation signal and a weighted error signal is formed. The latter is then used to impress an error correcting phase modulation on the carrier frequency signals.

27 citations


Journal ArticleDOI
TL;DR: This paper uses double Fourier analysis techniques to obtain the output harmonics as a function of pulsewidth, pulsing frequency, and output frequency and obtains the harmonICS as analytical functions and thus provides the necessary relationships for control studies and system optimization.
Abstract: In pulsewidth-modulated inverters used for variable-frequency applications, a number of harmonic control policies can be used. Most of these policies are complex to implement by hardware. The most simple and yet effective technique is synchronizing or the synchronized harmonic control policy. This paper uses double Fourier analysis techniques to obtain the output harmonics as a function of pulsewidth, pulsing frequency, and output frequency. The method obtains the harmonics as analytical functions and thus provides the necessary relationships for control studies and system optimization. The more significant theoretical results are provided and theoretical and experimental results obtained from a 25-kW three-phase pulsewidth-modulated inverter, are compared.

22 citations


Patent
15 May 1974
TL;DR: In this paper, a rotational or translational speed control of a motor driven member is determined by manipulating a set of digital switches, and the desired speed can be selected by manipulating the set of switches.
Abstract: The disclosed system utilizes digital electronic programming to establish the rotational or translational speed of a motor driven member. The desired speed can be selected by manipulating a set of digital switches. A stable oscillator is employed to generate a high frequency signal which is processed by frequency dividers to produce a modulaton frequency signal. The modulation frequency is supplied to an optical encoder having a rotary shaft adapted to be connected to a rotary member, the speed of which is to be controlled. The encoder is constructed and arranged to produce a phase variable output signal at the modulation frequency, the phase of such output signal being variable as a function of the shaft angle. The high frequency signal is also processed by digital circuits under the control of the digital selector switches to produce a variable reference frequency signal having a frequency corresponding to the modulation frequency plus or minus a number which is established by the setting of the selector switches. The speed control system includes means for comparing the frequency of the phase variable signal with the frequency of the reference signal. This comparison circuit controls a motor operating circuit which increases or decreases the speed of the drive motor for the rotary member, until the phase variable signal has the same frequency and phase as the reference signal. The digital generation of the reference frequency signal insures that its frequency is established and maintained with an extremely high degree of accuracy.

21 citations


Patent
20 Sep 1974
TL;DR: In this paper, a method and means for modulating the frequency of an analog signal to achieve a vibrato effect was proposed, in which the analog signal is transmitted through an analog shift register or delay line under the control of a digital clock signal and the frequency is varied at a rate equal to the desired rate of modulation.
Abstract: A method and means for modulating the frequency of an analog signal to achieve a vibrato effect wherein the analog signal is transmitted through an analog shift register or delay line under the control of a digital clock signal and wherein the frequency of the digital clock signal is varied at a rate equal to the desired rate of modulation of the analog signal. In this manner, the output of the shift register is a delayed version of the input thereto, with the frequency modulated at the same rate that the clock signal frequency is modulated. According to the preferred embodiment of the invention, first and second shift registers are utilized and the analog signal is divided into upper and lower frequency bands which are separately applied to the two shift registers. Furthermore the shift register which receives the lower frequency band is clocked at one-half the rate of the shift register which receives the higher frequency band.

19 citations


Patent
27 Feb 1974
TL;DR: In this article, an incremental ramp wave is utilized as a modulation reference, and intercepts between the modulation reference and a signal to be encoded are detected and/or predicted logically by examining the values of these two signals at predetermined intervals.
Abstract: Disclosed is a method of encoding information in a pulse width modulated nal using totally digital techniques. An incremental ramp wave is utilized as a modulation reference, and intercepts between the modulation reference and a signal to be encoded are detected and/or predicted logically by examining the values of these two signals at predetermined intervals.

17 citations


Patent
13 Sep 1974
TL;DR: In this article, a measure of the desired frequency is obtained by multiplying the known standard frequency by the ratio between the desired count and the standard count obtained in the two frequency counters, and a command pulse is generated at each coincidence and used to start and stop a pair of frequency counters adapted to count the desired and standard frequencies.
Abstract: A method of measuring a desired frequency by comparing it with a standard frequency. The zero crossings of both frequencies are detected. A command pulse is generated at each coincidence and is used to start and stop a pair of frequency counters adapted to count the desired and standard frequencies. A measure of the desired frequency is obtained by multiplying the known standard frequency by the ratio between the desired count and the standard count obtained in the two frequency counters.

16 citations


Patent
05 Aug 1974
TL;DR: In this paper, a following error measurement system for phase analog servo systems is disclosed, where the leading or lagging status of a phase-aided servo system's command signal with respect to its feedback signal is used to create a variable width error signal.
Abstract: A following error measurement system for phase analog servo systems is disclosed. The leading or lagging status of a phase analog servo system's command signal with respect to its feedback signal, is used to create a variable width error signal. This variable width error signal controls the counting of modulated command pulses received from the phase analog servo system. Since the frequency of the variable width error signal is proportional to the frequency of the modulated command pulses, the total count is normalized and a pulse weighted count is obtained. In addition, the conditioned variable width error signal controls the transfer of the pulse weighted count to a display system. Because the total count is normalized, the resultant display is also normalized for variations in the rate at which command pulses are applied to the phase analog servo system. Hence the measured following error is displayed.

12 citations


Patent
02 May 1974
TL;DR: An electronic circuit for generating pulse position modulation or phase modulation is described in this article. But the circuit is not suitable for the use of a generator and the output pulses of the trigger circuit are of constant magnitude and duration but vary in response to the modulating voltage.
Abstract: An electronic circuit for generating pulse position modulation or phase modulation. Pulse position modulation is generated by applying a composite signal, which is the summation of a radio frequency ramp voltage and a modulating voltage, to the input of a fixed threshold trigger circuit. The output pulses of the trigger circuit are of constant magnitude and duration but vary in time in response to the modulating voltage. Phase modulation is generated by passing the output pulses of the trigger circuit through a filter tuned to some odd harmonic of the frequency of said output pulses to recover a phase modulated sinewave.

Patent
03 Sep 1974
TL;DR: In this paper, the synthesis of a waveform which upon integration will approximate a sinusoid of controllable frequency and amplitude is disclosed. But the synthesizer is suitable as a variable speed AC motor drive, and the output waveform is synthesised by chopping a square wave using a variable width chop.
Abstract: The synthesising of a waveform which upon integration will approximate a sinusoid of controllable frequency and amplitude is disclosed. Any desired amplitude may be programmed for a particular frequency. The synthesiser is suitable as a variable speed AC motor drive. The output waveform is synthesised by chopping a square wave using a variable width chop. To obtain lower harmonic content, a chopped square wave is Walsh multiplied with another square wave of different frequency to produce a pulse width modulated waveform having a frequency equal to the frequency difference between the square waves. Methods for accurately controlling the difference frequency using variable digital dividers are disclosed.

Patent
30 Sep 1974
TL;DR: In this article, a frequency discriminator is used for frequency shift modulation in which a number of parallel channels are incorporated between a common frequency generator and a phase comparator and each channel includes a frequency divider provided with a phase adjusting circuit, while the different frequency dividers are cyclically adjusted in phase.
Abstract: In a receiver for frequency shift modulation an accurate demodulation of the received signal and a low sensitivity to noise and interference is obtained by using a frequency discriminator in which a number of parallel channels are incorporated between a common frequency generator and a phase comparator and in which each channel includes a frequency divider provided with a phase adjusting circuit, while the different frequency dividers are cyclically adjusted in phase as a function of the zero crossings in the received signal and the demodulated signal is derived from a lowpass filter connected to the phase comparator.

Patent
Kawamoto Kinji1
06 Sep 1974
TL;DR: A sampling modulation system for an electronic musical instrument has an audio frequency signal source, a sampling circuit, memory circuit for memorizing the sampled signals, an output circuit for reading out the signals from the memory circuit, a control circuit which generates a sampling pulse train and a reading pulse train, and a modulating signal source as mentioned in this paper.
Abstract: A sampling modulation system for an electronic musical instrument has an audio frequency signal source, a sampling circuit, a memory circuit for memorizing the sampled signals, an output circuit for reading out the signals from the memory circuit, a control circuit which generates a sampling pulse train and a reading pulse train, and a modulating signal source. At least either the sampling pulse train or the reading pulse train has the frequency modulated by the modulating signal generated from the modulating signal source so as to provide a periodical difference between the sampling frequency and the reading frequency and accordingly to produce a phase modulation.

Patent
26 Aug 1974
TL;DR: In this paper, a method and apparatus for adjusting the modulation signal levels of overlapping beams which define along points of equal signal levels within the overlap a directional axis which in turn defines a desired navigation course for an airplane or similar maneuverable apparatus.
Abstract: A method and apparatus for adjusting the modulation signal levels of overlapping beams which define along points of equal signal levels within the overlap a directional axis which in turn defines a desired navigation course for an airplane or similar maneuverable apparatus. At points offset from the directional axis, one or the other of the modulation signals will be greater in magnitude, depending on the direction of offset. The included angle between the two locus of points representing a predetermined difference in magnitude between the two modulating signals over the region between the landing field and the farthest reach of the beams defines the modulation course width for that particular difference in magnitude. In the illustrated embodiments, such a modulation course width may be effectively increased or decreased for a given antenna configuration and a given directional axis by altering the magnitudes of the modulation signals such that the difference in modulation levels is decreased or increased throughout the area of beam overlap. This is accomplished by introducing a portion of the modulation signal from one beam forming circuit into the other beam forming circuit, and viceversa, such that each radiated beam includes components of both modulation signals.

Patent
06 May 1974
TL;DR: In this article, a method for measuring the transmission quality of pulse controlled, phase difference modulated data signals is described, where phase scanning pulses are produced which occur in the centers of the consecutive modulation sections.
Abstract: A method for measuring the transmission quality of pulse controlled, phase difference modulated data signals is described. Phase scanning pulses are produced which occur in the centers of the consecutive modulation sections. The phase difference modulated carrier is subject to amplitude modulation by band limitation, and modulation sections of the phase difference modulated carrier are assigned to modulation sections of the amplitude signal. Scanning pulses occurring in the centers of the modulation sections of the amplitude signal are derived from the phase scanning pulses. By means of the aforementioned scanning pulses, instantaneous values of the amplitude signal are sampled and measured. The maximum and minimum instantaneous values which occur during an observation period are stored by corresponding measured values, and the difference between the two measured values is formed and serves as a measure for transmission quality.


Patent
Jr Theodore B Bozarth1
19 Jul 1974
TL;DR: In this article, an analog arithmetic circuit has a modulator circuit for coverting an analog direct current input signal into a variable duty cycle signal with the duty cycle being controlled by the amplitude of the analog input signal.
Abstract: An analog arithmetic circuit has a modulator circuit for coverting an analog direct current input signal into a variable duty cycle signal with the duty cycle being controlled by the amplitude of the analog input signal. The variable duty cycle signal is subsequently applied to a demodulator circuit. The demodulator circuit is driven by the variable duty cycle signal to produce a switching signal for energizing a second switching device arranged to control the application of a third analog signal to an output circuit. The switching of the second switching device is maintained in phase with the operation of the first switching device to produce an output analog signal having a predetermined relationship to the three input analog signals.

Patent
30 Oct 1974
TL;DR: A pulse generating circuit provides a series of pulses each of which is a given percentage or portion of the period of a source signal the frequency of which may vary over a fairly substantial range as discussed by the authors.
Abstract: A pulse generating circuit provides a series of pulses each of which is a given percentage or portion of the period of a source signal the frequency of which may vary over a fairly substantial range. This circuit recognizes a prescribed condition of the source signal to initiate a timing period the length of which is a function of the frequency of the source signal. Pulses each having a width of the period so timed are thus generated which pulses are a given percentage of the period of the source of the signal.

Patent
29 Mar 1974
TL;DR: In this paper, the authors measure the conversion of amplitude modulation to phase modulation and use it to test devices used in frequency modulated multichannel communication systems having amplitude modulation-to-phase modulation conversion.
Abstract: This method and apparatus measures conversion of amplitude modulation to phase modulation and is useful for any application wherein resultant unwanted phase modulation is to be measured, but is mainly intended for testing devices used in frequency modulated multichannel communication systems having amplitude modulation to phase modulation conversion which causes distortion of a desired frequency modulated signal.

Journal ArticleDOI
TL;DR: In this article, the quasi-optimal on-line demodulation of PFM signals in the presence of white Gaussian channel noise was derived by applying the extended Kalman filter theory to a state-space signal model.
Abstract: Novel demodulator structures are derived using a theory for the quasi-optimal on-line demodulation of pulse-frequency modulated (PFM) signals in the presence of white Gaussian channel noise. The basic demodulator consists of a phase-locked loop with time-varying gain elements. Furthermore, its integrators are appropriately reset as each new pulse is received. This modulator may be augmented with additional integrators and gain elements to achieve quasi-optimal demodulation with delay. The quasi-optimal demodulation approaches optimal demodulation, in the minimum mean-square-error sense, as the signal-to-noise ratio increases. The various quasi-optimal receivers are derived by application of the extended Kalman filter theory to a state-space signal model.

Journal ArticleDOI
TL;DR: The Volterra series approach was used to derive a simplified expression relating the single channel and multichannel cross modulation in a CATV amplifier as discussed by the authors, where the cross modulation from n unwanted carriers synchronously modulated is seen to be dependent upon the phase versus frequency variation of the third-order VOLTERRA transfer function of an amplifier only when the phase is constant for any frequency of interest is the increase in the magnitude of the cross-modulation vector given by 20 log n, n being the number of synchronous modulated carriers.
Abstract: The Volterra series approach is used to derive a simplified expression relating the single channel and multichannel cross modulation in a CATV amplifier The cross modulation from n unwanted carriers synchronously modulated is seen to be dependent upon the phase versus frequency variation of the third-order Volterra transfer function of an amplifier Only when the phase is constant for any frequency of interest is the increase in the magnitude of the cross-modulation vector given by 20 log n, n being the number of synchronously modulated carriers

Journal ArticleDOI
TL;DR: In this article, the use of a stepped phase shifter as an approximation to continuous phase shifting for serrodyne frequency translation is considered and variations in translation loss and suppression of undesirable components as a function of the number of steps used are presented.
Abstract: This correspondence considers the use of a stepped phase shifter as an approximation to continuous phase shifting for serrodyne frequency translation. Variations in translation loss and suppression of undesirable components as a function of the number of steps used is presented.

Proceedings ArticleDOI
10 Jun 1974
TL;DR: In this article, the capability of the d.c. converter employing pulse width modulation to attenuate a periodic disturbance in the voltage e s of its source of electric energy is examined.
Abstract: The capability of the d.c. converter employing pulse width modulation to attenuate a periodic disturbance in the voltage e s of its source of electric energy is examined. The attenuation of this disturbance is linked to the effects of pulse modulation and of the therewith associated feedback control process. Limitations for the attenuation of the harmonic content of e s as imposed by the pulse modulation process are indicated.

Patent
Allistair Towle1, Stanko Brcic1
25 Sep 1974
TL;DR: In this paper, an amplitude modulation system with a modulation control circuit including a limiter for the modulation signal, a detector for deriving a DC contr0l signal from the unmodulated carrier, and an adjustable network connected to the detector to produce a signal applied to a modulation controller circuit for adjusting depth of modulation was presented.
Abstract: An amplitude modulation system having a modulation control circuit including a limiter for the modulation signal, a detector for deriving a DC contr0l signal from the unmodulated carrier, a first adjustable network connected to the detector to produce a signal applied to a modulation control circuit for adjusting depth of modulation, and an additional adjustable network connected between the detector and the modulator to produce a signal for adjusting the modulated carrier.

Patent
01 Jan 1974
TL;DR: In this article, a modulation system for generating a train of substantially rectangular pulses, the trailing edges of alternate pulses being delayed by an amount proportional to a modulating signal and the remaining edges of the remaining pulses being advanced by a amount similarly proportional to the modulation signal, in order to provide an output signal in which the carrier and even-order sidebands are suppressed and the odd order sidebands have amplitudes given by the first kind with arguments dependent on the index of modulation.
Abstract: A modulation system for generating a train of substantially rectangular pulses, the trailing edges of alternate pulses being delayed by an amount proportional to a modulating signal and the trailing edges of the remaining pulses being advanced by an amount similarly proportional to the modulating signal, in order to provide an output signal in which the carrier and even order sidebands are suppressed and the odd order sidebands have amplitudes given by the odd order Bessel functions of the first kind with arguments dependent on the index of modulation. Optionally, a carrier signal component can be injected into the output signal in a controlled amount independent of the modulating signal by delaying the leading edges of alternate pulses by a predetermined constant amount and advancing the leading edges of the remaining pulses by the same amount.

Journal ArticleDOI
TL;DR: In this paper, the authors compared three basic stability criteria for systems containing an arbitrary number of pulse frequency modulators, which fall under three basic categories, namely, Lyapunov's second method, frequency domain method, and a direct method for global finite pulse stability.
Abstract: Stability criteria for systems containing an arbitrary number of pulse frequency modulators are considered, which fall under three basic categories, namely, Lyapunov's second method, frequency domain method, and a direct method for global finite pulse stability (GFPS) introduced earlier by the authors. The criteria are compared with respect to effectiveness (in terms of size of [parameter-] region sufficient for stability), generality (in terms of classes of applicable systems), and ease of application. The direct GFPS criterion is the simplest to apply and, at the same time, provides bounds on the number of pulses emitted by each modulator. Comparative examples yielded greater stability regions (of parameters) from the direct GFPS criterion than from (optimal application of) a recent frequency domain criterion of Gelig. A criterion based on Lyapunov's second method could provide good stability regions, but it is most difficult to apply, especially, for higher order systems.

Journal ArticleDOI
TL;DR: In this paper, a simple method of optical frequency shifting a laser Doppler signal is described, which employs a local oscillator heterodyne system where the signal beam is modulated in amplitude by either a light chopper or a rotating linear polarizer disk.
Abstract: A simple method of optical frequency shifting a laser‐Doppler signal is described. The method employs a local‐oscillator heterodyne system where the signal beam is modulated in amplitude by either a light chopper or a rotating linear polarizer disk. Photomixing the signal and reference beams at the photodetector will yield an output that will contain, among other terms, a term at the sum frequency of the Doppler and amplitude modulation frequencies. Due to the low frequency of amplitude modulation, this method is uniquely suited for frequency biasing of Doppler signals from scatterers moving at very low speeds.

Journal ArticleDOI
TL;DR: Comparisons with binary frequency modulation of the same data rate show that biternary frequency modulation can offer lower error rates only for receiver bandwidths less than 0.63 times the bit rate.
Abstract: The performance of a biternary f.m. system is investigated in the presence of additive Gaussian noise and receiver band limitation. The receiver bandpass-filter bandwidth is varied and, for each bandwidth, the frequency-deviation index that minimises the error probability is found. Comparisons with binary frequency modulation of the same data rate show that biternary frequency modulation can offer lower error rates only for receiver bandwidths less than 0.63 times the bit rate.