Topic
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•
28 Apr 2004
TL;DR: In this paper, the frequency offset between an average frequency of the output signal and the frequency dependent on the reference frequency is evaluated, and a frequency offset correction signal is injected into the circuit loop for correcting the evaluated frequency offset.
Abstract: A spread-spectrum clock signal generator comprises a circuit loop receiving a reference signal at a reference frequency and adapted to generate an output signal at an output frequency dependent on and locked to the reference frequency, and a modulator circuit generating a modulation signal at a modulation frequency; the modulation signal is injected into the circuit loop to induce a modulation of the frequency of the output signal with respect to the frequency dependent on the reference frequency. The circuit loop is a frequency-locked loop and has a bandwidth sufficiently higher than the modulation frequency, so that the output frequency tracks the modulation signal. Frequency-offset correction means are further provided, for evaluating a frequency offset between an average frequency of the output signal and the frequency dependent on the reference frequency, and for generating a frequency-offset correction signal which is injected into the circuit loop for correcting the evaluated frequency offset.
17 citations
TL;DR: In this paper, the effect of adding a modulating square wave of any amplitude is examined by solving the governing equations exactly, and the dependence of the accurrent amplitude on the dc potential and on the square wave's amplitude is formulated.
Abstract: The effect upon reversible linear-potential-scan voltammetry of adding a modulating square wave of any amplitude is examined by solving the governing equations exactly. This solution explains the origin of the "splitting effect" that had previously been observed empirically in the dc component. The ac component is derived in both the time domain and the frequency domain. In the former, it consists of a periodic function. displaying spikes whenever the square wave experiences a sign change. In the frequency domain, harmonics that possess odd multiples of the square wave's frequency are present, phase shifted by 45°. The dependence of the accurrent amplitude on the dc potential and on the square wave's amplitude is formulated. Comparisons are made with a recent simulative and experimental study of the same system.
17 citations
02 Oct 1988
TL;DR: A novel PWM (pulsewidth modulation) technique is proposed for a three-phase sine-wave PWM inverter with fluctuating input voltage and the validity of the method is verified in an experiment using a microprocessor-based control system.
Abstract: A novel PWM (pulsewidth modulation) technique is proposed for a three-phase sine-wave PWM inverter. The pulse width is designed to produce a sine-wave output voltage by numerical calculation based on a geometrical technique. The accuracy of output voltage and the harmonics in an output voltage waveform are discussed and compared with the results of the conventional triangulation method. A modified method is introduced for obtaining a PWM inverter with fluctuating input voltage. The validity of the method is verified in an experiment using a microprocessor-based control system. >
17 citations
22 Sep 2014
TL;DR: From the presented analysis, it has been shown BER performance can be maintained at a higher data rates by an increase in bandwidth and the number of pulses, and this scheme provides improved in system performance along with computational complexity.
Abstract: This paper investigates the modulation schemes in visible light communication (VLC) system. On-off keying (OOK), and pulse position modulation (PPM) one used widely in visible light communication, but recently some new ideas are proposed in order to realize a high performance communication system along with optimum performance in terms of power, bandwidth, capacity and data rate at acceptable complexity. This paper specifically combines the PPM and pulse shape modulation (PSM). The objective of this paper is to examine different types of pulse shaping and PPM in VLC system. From the presented analysis, it has been shown BER performance can be maintained at a higher data rates by an increase in bandwidth and the number of pulses. This scheme provides improved in system performance along with computational complexity. The BER performance of this scheme also compared to traditional (n-bit/symbols) schemes.
17 citations
Patent•
14 Jan 2008TL;DR: In this article, the authors proposed a method for varying the phases of two data signals at a first predetermined frequency, and performing multi-level phase modulation of a light based on the two signals whose phases are varied at a predetermined frequency.
Abstract: The disclosed device and method include varying phases of two data signals at a first predetermined frequency, performing multi-level phase modulation of a light based on the two data signals whose phases are varied at the first predetermined frequency, extracting a component having the first predetermined frequency from an optical signal subjected to the phase modulation, and controlling the phases of the two data signals based on the component extracted from the optical signal.
17 citations