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.

Modulation identification device

Abstract: A modulation identification device can be used for detecting the modulation type of a wirelessly transmitted and modulated RF signal without a-priori information on the kind of modulation used. The modulation identification device (1) comprises a n-port junction (17), n being an integer equal to or larger than three. The n-port junction (17) is supplied with the modulated RF signal (2) and a second RF signal (3) from a local oscillator. The n-port junction (17) outputs at least one third RF signal to at least one power detector (18). A signal processing unit (6) processes the power detected output of the n-port junction (17) to generate at least one flag (10) indicating the identified modulation type.

A single-chip microprocessor-based PWM technique for sinusoidal inverters

Abstract: A sinusoidal pulsewidth-modulation (PWM) technique suitable for single-chip-microprocessor-based control is described. The scheme can be considered as a digital alternative to the analog subharmonic method (SHM) in the sense that online real-time PWM control is possible, synchronization between carrier wave and signal wave is unnecessary, and low-order harmonics in the output voltage are well suppressed. The maximum output voltage is 15% larger than that obtained by the subharmonic modulation method at the same carrier frequency. >

Wireless audio transmission system

Abstract: A wireless audio transmission and reception system includes a pulse width amplifier, an up-converter, a transmitter, a receiver, a down-converter, an integrator, and a power amplifier to transfer an analog signal to a transducer such as a speaker. The pulse width amplifier receives an analog signal and modulates a pulse width of a timing signal with the analog signal. The pulse width of the timing signal is modulated such that the pulse width is proportional to the amplitude of the analog signal, and provides a pulse width modulated signal. The up-converter is in communication with the pulse width amplifier to receive the pulse width modulated signal and convert the pulse width modulated signal to a modulated carrier signal. The transmitter in communication with the up-converter to receive the modulated carrier signal and to transfer the modulated carrier signal wirelessly. The receiver receives the modulated carrier signal and transfers the modulated carrier signal to the down-converter that extracts the pulse width modulated signal from the modulated carrier signal. The down-converter transfers the extracted pulse width modulated signal to the integrator, which then restores the analog signal. The integrator transfers the recovered analog signal to the power amplifier for amplification and transfer to the transducer or speaker.

Detection of frequency-modulated tones in electromagnetic signals

Abstract: An apparatus and method for detecting a channel of a fiber-optic system. According to one embodiment, a filter is adapted to receive an electromagnetic signal resulting from modulation of a carrier frequency over a frequency range by a modulation signal. The filter has a plurality of transmissivity peaks over the frequency range, whereby the filter generates a plurality of intensity pulses as frequency of the electromagnetic signal varies over the frequency range. A detector is adapted to detect the modulation signal based on the plurality of intensity pulses. According to another embodiment, an electromagnetic signal corresponding to a channel and resulting from modulation of a carrier frequency over a frequency range by a modulation signal is received. A plurality of intensity pulses are generated as frequency of the electromagnetic signal varies over the frequency range, and the channel is detected in accordance with the intensity pulses.

Waveguide nonlinear optical frequency converter with integral modulation and optimization means

Abstract: An optical, waveguide, quasi-phase-matching frequency converter has integral means to vary the efficiency of the quasi-phase-matching frequency conversion process resulting in intensity modulation of the device output; said frequency converter has integral means to optimize the quasi-phase-matching frequency conversion process resulting in optimum device output; and said frequency converter has integral input signal polarization mode conversion means in optional combination with the conversion optimization means for modulating the optimized device output. Methods for modulating and optimizing the quasi-phase-matching frequency converted signal by electro-optically controlling the dispersion of the frequency converting medium are also disclosed.