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•
03 Nov 1997
TL;DR: In this paper, a method of wireless information transfer, especially for mobile communication, where an input signal (sl, g4) is subjected to a modulation in a transmitter (2-8) and reaches a receiver (11-15) via a transmission channel.
Abstract: A method of wireless information transfer, especially for mobile communication, whereby an input signal (sl, g4) is subjected to a modulation in a transmitter (2-8) and reaches a receiver (11-15) via a transmission channel. The transmitter produces angularly modified pulses having a frequency spectrum and carrying information, in such a way that said pulses can be time compressed in the transmitter by means of a filter (13) with a frequency dependent differential transit time, also called a group transit time, so that pulses with reduced duration and higher amplitude can arise, and at least one part of the information in the transmitter is impressed on the pulses by means of a modulation independent from the angle modulation and/or used to control an angle modulation parameter which can be detected in the receiver.
50 citations
Patent•
08 Sep 1997TL;DR: In this article, each individual channel is pre-chirped at the transmitter with replicas, or low-pass filtered replicas of the amplitude modulation applied to each of the other channels.
Abstract: In a WDM transmission system carrying amplitude modulated traffic in which significant cross-phase modulation occurs, each of the individual channels is pre-chirped at the transmitter with replicas, or low-pass filtered replicas of the amplitude modulation applied to each of the other channels. Prechirping of each individual channel with a replica of the amplitude modulation applied to that channel may be added in order additionally to provide compensation for self-phase modulation.
50 citations
TL;DR: The spectral responses of cat single primary auditory nerve fibers to sinusoidal frequency-modulated acoustic signals applied to the ear are examined and it is indicated that a demodulation process is occurring, which may be significant for speech recognition.
50 citations
TL;DR: In this article, two compact diode-pumped CW Nd:YAG-lasers (λ = 1.06 μm, P = 40 mW each) are used for optical excitation.
49 citations
TL;DR: In this article, the authors focused on the noise elimination at a selected frequency from the line voltage of a two-level three-phase inverter, when it is driven by random space-vector pulsewidth modulation.
Abstract: This study has focused on the noise elimination at a selected frequency from the line voltage of a two-level three-phase inverter, when it is driven by random space-vector pulse-width modulation. Distribution of noise power in a wide range of frequencies in the conventional random pulse-width modulation (RPWM) methods may cause system resonant frequency excitation. Therefore, it can increase the acoustic noise and vibration in loads of inverters, especially ac motors. Thus, for the effective utilization of RPWM techniques, it is necessary to cancel noise at a specified frequency. The proposed method is able to create a gap in the spectrum of the line voltage at a selective frequency in the human hearing range. Therefore, unlike conventional RPWM techniques, switching periods are determined based on the position of the rotary reference vector. The presented relation between switching periods and the reference vector is used for the conventional space-vector pulse-width modulation (SVPWM) and two-phase SVPWM. The simulation and experimental results confirm that the proposed method effectively creates a gap at the selected frequency in power spectrum density of the line voltage of the three-phase inverter using random SVPWM.
49 citations