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.

Amplitude modulation of underwater noise produced by seagoing vessels

Abstract: Data obtained from the processing of records of underwater noise produced by seagoing vessels are used to refine the model of the noise amplitude modulation caused by the rotation of the propeller shaft and ship roll and pitch in a seaway. Specifically, the width of the frequency band of the modulation process, the value of the modulation coefficient, and the distribution of the magnitude and phase of the modulation coefficient over the carrier frequency spectrum are investigated.

Phase locked oscillator and radar unit having the same

Abstract: An error detecting unit of a phase-locked oscillator evaluates difference between a reference phase error signal output from a phase detector and a phase error signal actually output from the phase detector when a reference frequency modulation signal is output from a voltage-controlled oscillator and further detects a frequency error of the frequency modulation signal from the voltage-controlled oscillator based on a rate of change of the difference. A correction unit of the phase-locked oscillator calculates an average value of the frequency error in a predetermined section of the frequency modulation signal and corrects center frequency of the frequency modulation signal by correcting the average value to be zero, and changes the rate of change of control voltage per control step based on comparison between at least two frequency errors in one cycle of the frequency modulation signal. Thus frequency shift of the frequency modulation signal is corrected.

Self-adaptive electro-magnetic induction heating controller

Abstract: The invention provides a self-adaptive electro-magnetic induction heating controller comprising a remote controller, a control board and a main unit. The main unit comprises a three-phase uncontrollable rectifying filter circuit module, a single-chip microcomputer main board, a control circuit power source system, a temperature control system, a protecting system, an alarm system, a heat radiation system, a setting switch circuit, a remote control board, a trigger board, an IGBT (insulated gate bipolar transistor) module, a pulse power output amplifier, an input terminal, output terminals, sensor terminals, an online testing interface and a serial communication interface. The control board consists of an automatic air breaker, a control keyboard, a power controller, a voltmeter, an ampere meter, a liquid crystal display screen, state indicator lamps and the like. By a control method of combining special independently developed software and PAM (pulse amplitude modulation), PWM (pulse width modulation) and PFM (pulse frequency modulation, work parameters such as pulse width and frequency are adjusted self-adaptively, heating coils different in size, shape and materials within a designed power range are matched automatically, and heating requirements of diversified user environments in the fields of industry and home application and the like can be met.

Power supply for silent discharge type load

Abstract: Since silent discharge in gas has been recognized as one of the most effective ways for ozone, ultraviolet and excimer laser generation, development of low cost and high effective driver for silent discharge load becomes a task of great importance. This paper presents a switched-mode power supply designed for such a type of load. A voltage source type resonant inverter operating under ZVS (zero voltage switching) principle and developed for driving a silent discharge (SD) type high-frequency ozone generation tube is introduced. PDM (pulse density modulation) and PFM (pulse frequency modulation) hybrid control strategy applied in this inverter allows achievement of zero voltage switching in all power regulating ranges (10-100%) that reduces total switching losses and EMI noises and increases total system efficiency. The developed inverter type ozonizer system has superior performances, simple power regulating scheme and appears to be promising in industrial ozone generation applications, however the same principles can be applied in the domestic units with lower power, which will be widely applied in the near future. The developed scheme has proven high performances for the ozone generation system both by simulation and experiment and now it is under implementation for the ultraviolet generating system. This paper introduces the design principles of such a power supply along with its structure, regulation method and operating performances.