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.

Generalized energy demodulation for large frequency deviations and wideband signals

Abstract: The Teager-Kaiser energy operator and the related energy separation algorithm (ESA) find numerous applications in various problems related to monocomponent AM-FM demodulation. This energy-operator-based approach, however, applies only to signals with narrowband frequency content, i.e., the information bandwidth and frequency deviation about the carrier are small relative to the carrier frequency. For signals with large frequency deviation, modulation indices, this approximation fails, and the ESA incurs large frequency/amplitude demodulation errors. In this letter, we develop a generalized energy-operator-based approach that uses frequency transformations derived from multirate operations such as decimation/interpolation and heterodyning. This generalized approach is shown to produce significant reduction of the demodulation error over the conventional ESA, particularly where the modulation index or frequency deviation is large.

Time division interpolator

Abstract: An electronic circuit is disclosed for generating an output signal having a frequency which is a selected multiple of a variable input signal frequency. To obtain the desired multiplication, a relatively high clock signal frequency is divided by a number which corresponds to the selected multiple to produce a second signal having a lower frequency than the clock signal frequency. The individual pulses of the lower frequency signal are counted during the time interval between two consecutive input signal pulses to generate a second, variable, number which is then used to divide the clock signal frequency in the time period immediately following the occurrence of the second of the two consecutive input signal pulses. The resulting output signal therefore occurs at a frequency which is equal to the frequency of the input signal multiplied by the desired multiplicative factor.

A comparative study of using random switching schemes for DC/DC converters

Abstract: This paper addresses a comparative investigation on the use of random modulation schemes for DC/DC power converters. The modulation schemes under investigation include randomized pulse position modulation, randomized pulse width modulation and randomized carrier frequency modulation with fixed and variable duty cycle. The study emphasizes the suitability and applicability of each scheme in DC/DC power converters, the randomness level on the effectiveness of spreading the dominating frequencies in constant frequency pulse width modulation scheme, and the low-frequency power spectral density (PSD) of each scheme. Validity of analyzes is confirmed experimentally by using a DC/DC buck converter, where the PSD of the output for each scheme is presented.

Sampling Effect Characterization of Digital SPWM of VSI in Time Domain

Abstract: This paper characterizes the sampling effect in digital sinusoidal pulse width modulation (SPWM) of voltage source inverter (VSI). The time-domain analysis presented in this paper establishes the relation between the fundamental frequency, carrier frequency, and the sampling frequency at different modulation indices of the SPWM. The analysis investigates the effect of sampling frequency of the digital controller on the output of the VSI. It is shown that the low-frequency harmonic components appear in the frequency spectrum of the VSI output voltage due to sampling. As a result, the output current of digitally controlled VSI is stepped in nature. The double Fourier integral solution of the switched waveform for inner and outer integral limits has been used to derive the expression. The integral solution is obtained using Jacobi-Anger expansions. The generalized results developed in this paper are useful to investigate the sampling effect in high switching frequency DSPWM. The proposed sampling effect has been analyzed for SPWM of single-phase H-bridge inverter. The analytical results are verified using simulation and experimental results. The experimental results have been obtained with the use of field-programmable gate array (FPGA) as a digital controller.

Transmission apparatus, communication apparatus and mobile radio apparatus

Abstract: Transmission apparatus capable of reducing distortion of the vector modulation wave that is the transmission output to a sufficiently small level is provided. An amplifying section ( 105 ) generates a vector modulation wave based on an amplitude component modulation signal and a phase modulation wave. A synchronous demodulating section ( 107 ) detects the vector modulation wave, generates a synchronous demodulation signal, and sends this to a band filtering section ( 108 ). The band filtering section ( 108 ) extracts a signal of the frequency component of the distortion from a synchronous demodulation signal outputted by the synchronous demodulating section ( 107 ). A controlling section ( 109 ) then refers to the distortion component signal extracted by the band filtering section ( 108 ), controls a delay time adjusting section ( 103 ) in such a manner that the signal level of the distortion component becomes small, adjusts a delay time difference between the amplitude component modulation signal and the phase component modulation signal, and reduces distortion of the modulation wave.