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Pulse-frequency modulation

About: Pulse-frequency modulation is a research topic. Over the lifetime, 4151 publications have been published within this topic receiving 53039 citations. The topic is also known as: PFM.


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Patent
29 Jul 2011
TL;DR: In this article, an apparatus for measuring intensity and/or range characteristics of an object(s), comprising of a signal source to emit modulation signals at a frequency, an illuminator to illuminate the object by a first modulation signal, and a sensor comprising a pixel, is presented.
Abstract: An apparatus for measuring intensity and/or range characteristics of an object(s), comprising: a signal source to emit modulation signals at a frequency(s); an illuminator to illuminate the object(s) by a first modulation signal; a sensor comprising a pixel(s), wherein the sensor creates a sampled correlated signal by sampling the correlation of a backscattered signal with a second modulation signal within the pixel; and a processor to determine range/ intensity characteristics of component returns within the pixel(s) by comparing sampled correlated signals using measurements(s), wherein the measurement(s) comprise first and second modulation signals having a characteristic(s) selected from: (a) two or more different modulation frequencies, (b) a different modulation frequency(s) and an offset of the correlation waveform, and (c) another different modulation frequency(s) and one selected from: the zeroth spatial frequency of the signal returns versus range and an approximation of the zeroth spatial frequency of the signal returns versus range.

18 citations

Journal ArticleDOI
TL;DR: The dependence of modulation thresholds on carrier contrast was found to be very similar, irrespective of the modulation frequency, carrier frequency and kind of modulation selected, and was in agreement with known results of contrast-difference threshold measurements and of masking experiments.

18 citations

Patent
21 May 2004
TL;DR: In this article, a system for detecting the eigen frequency of a sensing coil in a fiber optic gyro (FOG) that includes a fiber coupler connected to the light source, an integrated optics chip (IOC) capable of modulating light received from the light-source via the fiber coupling, a sensing coils in communication with the IOC, a first modulation generator for imparting a first modulation signal to the ground station, and a photodetector for receiving light returning from the sensing coil that is representative of a rotation rate of the sensing coils.
Abstract: A system for detecting the eigen frequency of a sensing coil in a fiber optic gyro (FOG) that includes a fiber coupler connected to the light source, an integrated optics chip (IOC) capable of modulating light received from the light source via the fiber coupler, a sensing coil in communication with the IOC, a first modulation generator for imparting a first modulation signal to the light, and a photodetector for receiving light returning from the sensing coil that is representative of a rotation rate of the sensing coil. Along with the foregoing there is provided a second modulation generator for imparting a second, preferably sinusoidal, modulation signal to the light, a high-frequency demodulator in communication with a signal produced, at least indirectly, by the photodector, and a low-frequency demodulator in communication with the high-frequency demodulator. The high-frequency demodulator receives the first modulation signal as a reference frequency and the low-frequency demodulator receives the second modulation signal as a reference frequency. An output of the low-frequency demodulator represents a magnitude and sign of a frequency difference between a frequency of the second modulation signal and an even-harmonic of the eigen frequency.

18 citations

Patent
09 Oct 2003
TL;DR: In this paper, the amplitude-modulated wave is supplied to an antenna section including a resonance circuit via the collector thereof, and is transmitted as an electromagnetic wave from the antenna section.
Abstract: A shaped-wave application section inputs a first pulse signal corresponding to transmission data output from a transmission data output section, and applies, to a modulation and amplification section, a signal wave corresponding to a second pulse signal such that the waveform of the first pulse signal is shaped. The pulse signal applied to the base of the transistor of the modulation and amplification section is amplitude-modulated into an amplitude-modulated wave in which the amplitude-modulated portion is strengthened, in accordance with the signal wave corresponding to the second pulse signal applied to the emitter thereof. The amplitude-modulated wave is supplied to an antenna section including a resonance circuit via the collector thereof, and is transmitted as an electromagnetic wave from the antenna section.

18 citations

Journal ArticleDOI
TL;DR: An auto-capacitor-compensation pulse frequency modulation (ACC-PFM) controller, combining peak and valley current-mode controls, is proposed to resolve the issue of unbalanced flying capacitor voltage, as well as to regulate the output voltage.
Abstract: A three-level boost converter enables efficient voltage step-up power conversion with high power density by reducing the inductance and blocking voltage requirements in a conventional boost converter. An auto-capacitor-compensation pulse frequency modulation (ACC-PFM) controller, combining peak and valley current-mode controls, is proposed to resolve the issue of unbalanced flying capacitor voltage, as well as to regulate the output voltage. The capacitor balance is further strengthened through a delay-equalized level shifter that generates duty ratios with only sub-nanosecond deviations. The step-up power conversion from the input voltage of 0.3–3.0 V to the output voltage of 2.4–5.0 V is demonstrated through a prototype converter implemented in a 65-nm CMOS process with 0.28 mm2 active area. This converter achieves 96.8% peak efficiency and an 83-mA peak output current, with an 8 $\times $ peak step-up conversion ratio.

18 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202316
202228
202143
202055
201950
201860