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Showing papers on "Pulse-frequency modulation published in 1984"


Journal ArticleDOI
01 Jul 1984
TL;DR: In this paper, the authors reviewed the progress in the development of high-speed electrooptic A/D converters, which operate at 1 gigasample/second (GS/s) in 2-and 4-bit structures for 500-MHz analog bandwidth.
Abstract: Progress in the development of high-speed electrooptic A/D converters is reviewed. A/D converters of this type have been operated at 1 gigasample/second (GS/s) in 2- and 4-bit structures for 500-MHz analog bandwidth. The converter consists of an array of LiNbO 3 guided-wave interferometric modulators that function as an analog amplitude analyzer, pulsed lasers for optical sampling, and high-speed monolithic comparators/demultiplexers to generate the digital levels and slow the data to ECL-compatible rates. The operational principles of the converter are summarized and a performance analysis presented. The analysis indicates that with currently attainable components, conversion in the 4- to 6-bit range at rates from 1 to 3 GS/s is feasible. Experimental results for several converters are summarized, including a description of beatfrequency tests for analog signals with frequency content up to 500 MHz that indicate the analog bandwidth capabilities of this device. The electrooptical technology is compared to competing high-speed A/D technologies in Si, GaAs, and superconducting materials and the relative merits analyzed. It is found that the electrooptic approach eliminates some of the fundamental and severe problems of conventional converters (e.g., sampling pickup and large numbers of comparators). Finally, application of this converter to wide-band signal-processing problems is described. It is noted that there are numerous applications where a moderate number of bits at a high (gigahertz) sampling rate is attractive.

93 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that the spectrum of a single-mode semiconductor laser under continuous microwave modulation is locked to a single longitudinal mode for optical modulation depths up to ∼ 80 percent, beyond which the spectrum breaks into multimode oscillation.
Abstract: Experimental observations of the lasing spectrum of a single-mode semiconductor laser under continuous microwave modulation reveal that the lasing spectrum is apparently locked to a single-longitudinal mode for optical modulation depths up to ∼ 80 percent, beyond which the lasing spectrum breaks into multimode oscillation. The width of the envelope of the multimode spectrum increases very rapidly with further increase in modulation depth. These results are satisfactorily explained by a theoretical treatment which gives simple analytic results for the time evolution of the individual longitudinal modes. It also yields considerable insight into spectral dynamics, and enables one to predict the dynamic lasing spectrum of a laser from its CW lasing spectra at various output powers. The results can also be used to predict the amount of spectral envelope broadening under single or pseudo-random pulse modulation.

32 citations


Patent
09 Feb 1984
TL;DR: In this article, an outdoor microwave transceiver area intrusion detection system includes circuitry for both amplitude and frequency modulation of the microwave carrier signal pulses, which are transmitted at approximately a 50% duty cycle pulses, from a radar antenna to a target.
Abstract: An outdoor microwave transceiver area intrusion detection system includes circuitry for both amplitude and frequency modulation of the microwave carrier signal pulses, which are transmitted at approximately a 50% duty cycle pulses, from a radar antenna to a target. The return signal is mixed with a portion of the transmitted signal to produce first and second doppler frequency signals which are amplified and sampled during a narrow gating pulse. The two resulting sampled doppler frequency signals are alternately switched, in synchronization with the amplitude and frequency modulation signals, into first and second sample/hold circuits to reconstruct the first and second doppler frequency signals. The reconstructed signals are coupled to a differential amplifier to obtain a "range signal" which is proportional to the phase difference between the first and second doppler signals. The range signal is amplified and used to set an alarm circuit if its amplitude exceeds a certain threshold level for a certain interval of time. Signals from "close in" targets, due to rain on the radome surface and the like, are eliminated by the low value of the range signal. Signals from distant targets are cut off by the narrow gating pulse.

32 citations


Patent
06 Aug 1984
TL;DR: In this article, the apparent frequency of the signal at the ends of sampling periods (e.g., half cycles) is derived from successively derived apparent frequencies and the rate of change in frequency is calculated.
Abstract: A method of developing a signal representative of the instantaneous frequency of an alternating current signal encompasses first determining the apparent frequency of the signal at the ends of sampling periods (e.g., half cycles). From successively derived apparent frequencies the rate of change in frequency is calculated. The actual frequency signal is then generated as a function of the apparent frequency and the rate of change. In a specific implementation, the method is employed to develop a signal representative of the rotational speed of a motor.

26 citations


Patent
03 Feb 1984
TL;DR: In this article, a modulating wave signal whose phase abruptly changes is compared with a carrier signal to generate a pulse width modulation pulse, where the carrier signal is a sine wave signal having a frequency n times as high as that of the modulating signal.
Abstract: A modulating wave signal whose phase abruptly changes is compared with a carrier signal to generate a pulse width modulation pulse. The carrier signal is a sine wave signal having a frequency n times as high as that of the modulating signal and synchronized with the modulating signal. A phase of the carrier abruptly changes by a factor of n as the phase of the modulating signal abruptly changes. Thus, a pulse with modulation pulse which causes an output voltage of a pulse with modulation inverter to be sinusoidal is generated even if the phase of the modulating wave signal abruptly changes.

26 citations


Patent
17 Feb 1984
TL;DR: In this article, the Sagnac effect is applied to phase modulation at the first and second frequencies of a fiber optic rotation sensor to cancel the phase shift produced in the phase difference by the rotation rate.
Abstract: A fiber optic rotation sensor, employing the Sagnac effect comprising all fiber optic components positioned along a continuous, uninterrupted strand of fiber optic material. The rotation sensor includes a detection system utilizing a modulator or modulators for phase modulating at first and second frequencies light waves which counter-propagate through a loop formed in the fiber optic strand. The second phase modulation is at a frequency much lower than the first frequency and comprises a phase ramp signal which is applied to the counter-propagating light waves. The phase difference modulation which results from application of the phase ramp defines a substantially DC value which may be adjusted to bias the counter-propagating light wave phase difference to substantially null the phase shift produced in the phase difference by the rotation rate. Because the phase ramp modulation signal is simulated from a periodic waveform, an output signal from the sensor is gated synchronously with respect to the phase modulation at the second frequency so that the detected optical output signal is provided only during those intervals when it is influenced by the ramped portion of the phase modulation signal. A phase sensitive detector generates a feedback error signal proportional to the magnitude of the optical output signal at the first phase modulation frequency. The feedback error signal controls a modulator which controls the amplitude of the second frequency driving signal for the phase modulator such that the signal at the first phase modulation frequency in the output signal from the rotation sensor is substantially cancelled by the phase difference modulation produced at the second modulation frequency during the interval when the optical output signal is present.

17 citations


Journal ArticleDOI
TL;DR: In this paper, a triangular timing wave of frequency f = 6?N?F is used where F is the reference wave frequency, and N? 1 is an integer, and a comparative analysis is presented of the PWM signal generated with this strategy with respect to a similar signal generated by means of a "traditional" triangular modulation strategy.
Abstract: A pulse-width modulation (PWM) strategy used to generate a control signal for an electronic switching inverter is described. A triangular timing wave of frequency f=6?N?F is used where F is the reference wave frequency, and N? 1 is an integer. The polarity of the timing wave is the same as the polarity of the half period of the reference wave. A comparative analysis is presented of the PWM signal generated with this strategy with respect to a similar signal generated by means of a "traditional" triangular modulation strategy.

15 citations


Patent
03 May 1984
TL;DR: In this paper, a modulation signal is applied to the phase-locked loop, so that high frequency modulation signals directly modify the control signal which determines the frequency of the oscillator, and low-frequency modulation signals alter the divisor value of the variable frequency divider so as to modify the frequency characteristics of the phase locked loop.
Abstract: A signal generator is arranged to produce frequency or phase modulation at frequencies which extend from a high value down to zero, i.e. to a d.c. level shift. The output oscillator forms part of a phase locked loop which also includes a variable frequency divider. A modulation signal is applied to the loop, so that high frequency modulation signals directly modify the control signal which determines the frequency of the oscillator, and so that low frequency modulation signals alter the divisor value of the variable frequency divider so as to modify the frequency characteristics of the phase locked loop. Quantization noise is reduced by applying a masking signal to an analogue-to-digital converter which utilizes the low frequency modulation signals to alter the divisor value.

14 citations


Journal ArticleDOI
TL;DR: In this article, the influence of regular and random phase modulation on the nonlinear propagation of ultrashort pulses in optical fibers was studied and an analysis was made in the constant channel approximation using path integrals.
Abstract: A study is made of the influence of regular and random phase modulation on the nonlinear propagation of ultrashort pulses in optical fibers. An analysis is made in the constant channel approximation using path integrals. It is shown in particular that steady-state pulse propagation regime does not occur for regular phase modulation. This regime may be achieved for a statistical-average pulse with random phase modulation.

13 citations


Patent
11 Jun 1984
TL;DR: In this article, the amplitude of a modulation signal at the constant times of a basic positive arcuate wave, and forming a waveform containing a plurality of harmonics of odd power, is used to enhance the torque of a motor within a range of the prescribed voltage.
Abstract: PURPOSE:To enhance the torque of a motor within a range of the prescribed voltage by holding the amplitude of a modulation signal at the constant times of a basic positive arcuate wave, and forming a waveform containing a plurality of harmonics of odd power. CONSTITUTION:With a phase signal theta as an address a modulation signal of the maximum amplitude (1/2)X3 is read out from a memory 1, and those for three phases are generated. Multipliers 2-4 multiply the modulation signal by a voltage command A for controlling the gain of the signal to obtain a modulation signal limited to the amplitude (a/2)X3 . On the other hand, a carrier generator 5 generates a carrier signal of a triangular wave synchronized with the modulation signal in the frequency of (3+6n) times of the signal of the modulation signal. Comparators 6-8 compare the carrier signal with the modulation signal to generate 3-phase PWM signal, thereby operating an inverter 9. The drive current contains low frequency harmonics, a large torque is generated in a motor 10, and a torque ripple and the copper loss of the harmonics remain low.

12 citations


Patent
24 Sep 1984
TL;DR: In this article, the authors proposed a self-clocking modulation system where a carrier signal is modulated by an input signal having a variable amplitude, either analog or digital, and the modulated signal is demodulated by either or both of the techniques of zero-crossing detection and peak-amplitude detection.
Abstract: A modulation system wherein a carrier signal is modulated by an input signal having a variable amplitude, either analog or digital. The amplitude of the input signal is sampled every predetermined fractional cycle of the modulated signal; and the carrier signal is modulated in response to the sampled amplitude of the input signal to provide a modulated signal of which each predetermined fractional cycle has an amplitude and a duration that are inversely proportional to each other and related to the sampled amplitude of the input signal. The modulated signal is demodulated by either or both of the techniques of zero-crossing detection and peak-amplitude detection. The system is self-clocking, without discontinuous phase or amplitude changes and without DC components being introduced. The system transmits its own signal-recovering clock information and thereby permits modulation at a rate in excess of the carrier signal frequency.

Patent
23 Aug 1984
TL;DR: In this paper, an electronic tone ringer provides a distinctive ringing capability through the use of two oscillators which allow selection of four tones and four modulation rates, in determining the type of tone generated, formattable inputs select between frequency shift or amplitude modulation modes.
Abstract: An electronic tone ringer provides a distinctive ringing capability through the use of two oscillators which allow selection of four tones and four modulation rates. In determining the type of tone generated, formattable inputs select between frequency shift or amplitude modulation modes or disabling the modulation altogether to generate a single tone. In the frequency shift mode, two fundamental frequencies are generated which are related by a predetermined ratio, the output tone alternating between these two frequencies at one of four selectable modulation rates. In the amplitude modulation mode, a single frequency is switched on and off at the selected modulation rate. All of the tones are produced with a duty cycle appropriate for driving an electromagnetic acoustic transducer.

Journal ArticleDOI
TL;DR: In this paper, the configuration of the 555 Timer from the pulsewidth and frequency modulation viewpoint is analyzed, and the governing expressions for the design and analysis of pulse-width modulators are provided.
Abstract: This paper analyzes the configuration of the 555 Timer from the pulse-width and frequency modulation viewpoint, derives the governing expressions, and provides practical nomograms for the design and analysis of pulse-width and frequency modulators. Suitable examples are also included. The limitations of the commercially available 555 Timer can easily be overcome by employing discrete components in the implementation along with high-speed voltage comparators and gates.


Journal ArticleDOI
TL;DR: In this paper, an experimental investigation was made of a single-frequency traveling-wave ring laser subjected to sinusoidal loss modulation, where the dependence of the laser response on the depth of modulation exhibited a hysteresis.
Abstract: An experimental investigation was made of a single-frequency solid-state (YAG:Nd3+) traveling-wave ring laser subjected to sinusoidal loss modulation. At a fixed modulation frequency an increase in the depth of modulation first resulted in nonlinear distortions of the laser response and then caused an abrupt change to pulsed operation at a repetition frequency equal to the loss modulation frequency. A further increase of the modulation depth resulted in complicated lasing, bifurcated increase in the period, and eventually emission characterized by a random variation of the amplitude and of the interval between the pulses. At the maximum experimentally attainable depths of modulation this random or autostochastic lasing changed to regular pulsing at a repetition frequency equal to half the loss modulation frequency. The dependence of the laser response on the depth of modulation exhibited a hysteresis. All the experimental results, including the autostochastic lasing regime, were in good agreement with the results obtained by numerical solution of the equations describing a solid-state ring laser.

Patent
19 Apr 1984
TL;DR: In this paper, a modulation analyser (MA) is proposed to detect signals of unknown origin with accuracy even in the event of substantial power and signal amplitude fluctuations and a poor signal-to-noise ratio.
Abstract: In monitoring the radio spectrum for the possible presence of signals of unknown origin, it is not only necessary to detect signals of this type with accuracy even in the event of substantial power and signal amplitude fluctuations and a poor signal-to-noise ratio. It is moreover also necessary to identify their modulation type and signal structure quickly and reliably by means of automatic modulation analysis if the intention is to be able to demodulate and analyse them. For a radio monitoring system of this type, a modulation analyser (MA) is proposed which, along with a control and evaluation circuit (ST), has a signal detector (SD) for the modulation characteristics and a high-resolution spectrum analyser (SA) which is similarly controlled by the latter. The spectrum analyser periodically samples the frequency of the signal fed to it in the width of a speech channel and supplies the sampling values which are in each case associated with a frequency interval to a histogram generator which simultaneously retrieves from the generated signal regularity pattern the fundamental signal criteria which are required in order to identify the signal composition.

Patent
17 Apr 1984
TL;DR: In this article, a phase modulation low power integrated circuit communications arrangement which employs a frequency shift oscillator is disclosed, where the oscillator operates normally at a first frequency and is keyed to a second frequency for brief intervals to introduce cumulative first frequency phase change in an output signal.
Abstract: A phase modulation low power integrated circuit communications arrangement which employs a frequency shift oscillator is disclosed. The frequency shift oscillator operates normally at a first frequency and is keyed to a second frequency for brief intervals to introduce cumulative first frequency phase change in an output signal. Subquadrature and larger increments of phase shift, spurious frequency component rejection with wave filters, and low power amplification of the modulated signal are also disclosed. Specifically, transitions in either (or both) of a pair of binary input signals cause a 45-degree (or 90-degree) phase shift in the phase-modulated carrier, unlike standard DQPSK modulation.

Patent
13 Feb 1984
TL;DR: In this article, a detector circuit for detecting a phase or frequency error of an input signal is proposed, where one mode of at least two detection modes is selected according to the phase or a frequency of the input signal with each mode having a reference value of a phase of the signal and reference values of the detection modes being different from each other.
Abstract: A detector circuit for detecting a phase or frequency error of an input signal. One mode of at least two detection modes is selected according to a phase or a frequency of the input signal with each mode having a reference value of a phase or a frequency of the input signal and reference values of the detection modes being different from each other. A pulse signal having a phase corresponding to a difference between an actual phase or frequency of the input signal and the reference value of the phase or the frequency is generated, and a predetermined carrier signal is pulse width modulated with a predetermined modulation factor in response to the pulse signal, the modulation factor being different for each detection mode.

Journal ArticleDOI
01 Apr 1984
TL;DR: A novel frequency-to-code converter (fDC) circuit is described in this letter in which voltage levels are substituted by frequency numbers and conversion time is equal to the period of the input hertz.
Abstract: A novel frequency-to-code converter (fDC) circuit is described in this letter. In principle, this fDC is an analog of flash ADC in which voltage levels are substituted by frequency numbers. Ingenious subcircuits, developed to generate reference frequencies and high-low frequency discriminating flags are incorporated in it. Conversion time is equal to the period of the input hertz.

Patent
17 May 1984
TL;DR: In this paper, a radio receiver for frequency modulated signals in which direct conversion techniques are used to provide zero I.F. quadrature baseband signals I & Q is presented.
Abstract: A radio receiver for frequency modulated signals in which direct conversion techniques are used to provide zero I.F. quadrature baseband signals I & Q. The I & Q signals are limited (11, 12) to form square wave signals and pulse forming networks (13, 14) derive pulse sequences the frequencies of which represent the polarity changes in the square wave signals. Each square wave is multiplied (15, 16) by the pulse sequence derived from the other square wave to produce a unipolar pulse train. The two unipolar pulse trains are combined (17) to give a digital output signal the frequency of which is equal to the sum of the frequencies of the two pulse trains. Low pass filtering the output signal produces a simulation of the original baseband modulation.

Journal ArticleDOI
Nakamura Masaru1, Nobuo Suzuki, Y. Uematsu, T. Ozeki, Shigeki Takahashi 
TL;DR: In this paper, the relation between laser linewidth and modal noise was studied in a pulse frequency modulation transmission system through employing a distributed feedback laser, which shows linwidth broadening of more than 2 A.
Abstract: The relation between laser linewidth and modal noise was studied in a pulse frequency modulation transmission system through employing a distributed feedback laser which shows linewidth broadening of more than 2 A. A 6-dB signal-to-noise ratio fluctuation for a 7-km transmission system, using a conventional Fabry-Perot laser, was reduced to 0.3 dB for 1.8-A linewidth. It is pointed out that more than 1-A linewidth is required to reduce the modal noise and to obtain a high-quality PFM transmission system.


Journal ArticleDOI
TL;DR: A method for the implementation of the on-line controller and the modulator, using the modified maximum principles (MMP), is presented and illustrated by an example.
Abstract: The problem of finding the optimal control sequences for pulse frequency modulated (PFM) systems with quadratic performance indices and fixed final time is considered. A method for the implementation of the on-line controller and the modulator, using the modified maximum principles (MMP), is presented and illustrated by an example.

Journal ArticleDOI
TL;DR: In this article, an analysis of the dynamics of modulation of a light signal in an active medium pumped by an electron beam modulated at microwave frequencies is made, where the quasisteady approximation is used to find the relationship between the velocities of propagation of maxima of the light signal and of the pump wave.
Abstract: An analysis is made of the dynamics of modulation of a light signal in an active medium pumped by an electron beam modulated at microwave frequencies. The quasisteady approximation is used to find the relationship between the velocities of propagation of maxima of the light signal and of the pump wave, and also the relationship between the depth of modulation of the light signal and the repetition frequency of the pump pulses. Numerical calculations are used to analyze the propagation of light (? = 430 nm) in an He?Sr mixture pumped by pulses of f = 500 MHz frequency with an average current density = 5 A/cm2. It is shown that deep modulation is possible.

Patent
06 Sep 1984
TL;DR: In this paper, the authors proposed to improve the linearity without requiring strict waveform equivalence by constituting the titled demodulator of a clamp circuit applying clamping at signal peak, a monostable multivibrator triggered at the falling of a pulse and a low pass filter.
Abstract: PURPOSE: To improve the linearity without requiring strict waveform equivalence even if the band of a transmission line is narrow, by constituting the titled demodulator of a clamp circuit applying clamping at signal peak, a monostable multivibrator triggered at the falling of a pulse and a low pass filter. CONSTITUTION: Since a capacitor 10 is charged when a signal potential gets higher than the clamp potential, the output impedance of a transistor (TR)9 is lower. TRs 9, 12, the capacitor 10 and a diode 11 clamp the signal peak to attain DC regeneration even to a pulse train subject strongly to band limit. Further, an inverter 13 inverts the signal to set an RS flip-flop at the rising of the signal and reset it at the rising of the signal through a delay circuit 14. The pulse width depends only on the delay time of a delay 14 and a pulse with constant width is obtained. The regenerated pulse is demodulated by a low pass filter. COPYRIGHT: (C)1986,JPO&Japio

Journal ArticleDOI
TL;DR: In this paper, the frequency deviation per unit modulator current and lasing spectra were analyzed in cleaved-coupled-cavity (CCC) lasers.
Abstract: Enhanced frequency modulation in cleaved‐coupled‐cavity lasers is analyzed and results for frequency deviation per unit modulator current and lasing spectra are presented. Strong sensitivity to gap spacing and bias point are reported and nonlinearities are shown to limit distortionless analog frequency modulation. In a typical case, a 40‐μA peak modulation current produces a 200‐MHz maximum frequency deviation with 2% distortion.

Patent
16 Apr 1984
TL;DR: In this article, a conventional magnetometer produces an output signal (10) which comprises a series of pulses (12, 14, 16) each of these pulses has a beat frequency maximum.
Abstract: A conventional magnetometer produces an output signal (10) which comprises a series of pulses (12, 14, 16). Each of these pulses has a beat frequency maximum. These pulses are input to a comparator (50) which makes a comparison to a threshold voltage V0 to produce a bi-level detected signal at a line (62). The detected signal is input to an integrator (52) which produces a series of pulses (78, 80, 82) corresponding respectively with the magnetometer output signal pulses (12, 14, 16). The two states of the detected signal corresponding to positive and negative integration. The time period for the positive integration is proportional to the beat frequency maximum time width period for the corresponding magnetometer output signal pulse. Thus the integrated pulses (78, 80, 82) have an amplitude which is a measure of the maxima time width periods for the corresponding magnetometer signal pulses.

Journal ArticleDOI
TL;DR: In this paper, a practical scheme for solving the resetting term problem in PFM control systems is presented, where the modulator can be described mathematically without resetting terms.
Abstract: When analysing type-II pulse-frequency modulated (PFM) control systems, particularly when attempting to optimize these systems, the `resetting term' in the equation describing the modulator makes the analysis very awkward. An equivalent set of equations is given which show that this modulator can be mathematically described without the resetting term. A novel practical scheme for accomplishing this is presented.

Journal ArticleDOI
TL;DR: In this paper, the authors describe a novel control circuitry that generates the three-phase sinusoidal pulse width modulation signals using a single phase reference signal and a triangular carrier signal.
Abstract: Pulse Width Modulation is widely used in static power inverters (d.c. to a.c. converters) to control the output voltage and the harmonic content in it. Sinusoidal pulse width modulation is known to produce the least harmonic content in the inverter output. This paper describes a novel control circuitry that generates the three-phase sinusoidal pulse width modulation signals using a single phase sinusoidal reference signal and a triangular carrier signal. The advantages of this circuit are discussed and experimental results are presented

Patent
29 Aug 1984
TL;DR: In this article, the color difference signals are adjusted at the input of the A/D converter (10) in amplitude or controlled so that the dynamic range of the converter independent of the original amplitude of Farbdiffarenzsignale is always fully utilized.
Abstract: In the analog / digital conversion of two color difference signals, for example for recording after the Timeplex-Systam, the color difference signals are adjusted at the input of the A / D converter (10) in amplitude or controlled so that the dynamic range of the converter independent of the original amplitude of Farbdiffarenzsignale is always fully utilized. After the D / A re-conversion, the amplitude is regulated back again to the original value. This is improved in transmitting the signal to noise ratio.