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.

Theory of frequency modulation detection for low modulation frequencies.

Abstract: There is general agreement that the frequency difference limen measured in a two‐sine‐tone frequency discrimination experiment is smaller than that measured in a frequency modulation (FM) experiment. We present a model of frequency modulation detection for low modulation frequencies, within the framework of signal detection theory, which accounts well for the observed difference between frequency discrimination experiments and FM detection experiments. The FM detection model also predicts psychometric functions for detection of FM with different modulation waveforms. FM detection experiments with square, sine, trapezoid, and triangle FM are in reasonable agreement with the model predictions.

Phase locked loop frequency modulator using fractional division

Abstract: A frequency modulation circuit includes a phase-locked loop having a reference frequency input and a controlled frequency output. The phase-locked loop has a phase detector, a filter and a voltage-controlled oscillator and, in a feedback path between the output and the phase detector, a frequency divider. Also included is a converter converting an input signal to a digital modulation signal M, and an adder inverting the most significant bit of the digital modulation signal and adding it to a digital word representing a selected frequency. The frequency divider divides a fractional number (N.F)±M, where N is an integer, F is a fraction and M is the digital value of modulation data. This configuration is advantageous because data can be taken directly from the analog-to-digital output to the adder with no data translation, the modulation signal M could also be provided from a processor data bus, the peak deviation is selectable, and no carrier offset results from injecting the modulation signal into the phase-locked loop.

A new PWM/PFM control technique for improving efficiency over wide load range

Abstract: This paper proposed a novel controlling technique of pulse width modulation (PWM) mode and pulse frequency modulation (PFM) mode to keep the high efficiency within width range of loading. The novel control method is using PWM and PFM detector to achieve two modes switching appropriately. The controlling technique can make the efficiency of current mode DC-DC buck converter up to 88% at light loading and this paper is implemented by TSMC 0.35 mum CMOS process.

The Compatibility Problem in Single-Sideband Transmission

Abstract: Under the assumption of simultaneous amplitude and phase modulation of a carrier, a study is made of the relations that must hold between the envelope and the phase of a single-sideband wave. In particular, it is shown that absolute compatibility with standard AM receivers employing a linear envelope detector cannot possibly be achieved with the spectral economy of conventional single sideband. On the other hand, if one conveys the message function in the square of the envelope rather than in the envelope itself, it is shown that a phase function can be found for which the hybrid wave occupies a spectral width equal to that of a conventional single-sideband (SSB) system. Distortionless detection is achieved with a square-law envelope detector. The operations required to generate this square-law SSB signal are described in detail.

Spectral distortion properties of the integral pulse frequency modulation model

Abstract: The integral pulse frequency modulation (IPFM) model has been used for the following two purposes. First, it has been utilized to verify the correspondence between the spectral structure of autonomic input and the estimated spectrum of heart rate variability (HRV), relying mainly on the theoretical work of Bayly (1968). Second, the IPFM model provides a framework for evaluating how precisely the proposed method of HRV analysis could estimate the input spectral structure. However, the appropriateness of the IPFM model for both purposes has not been examined sufficiently in realistic situations. Here, the spectral structure of the pulse train generated by the IPFM model is theoretically derived for an input signal containing multiple frequency components. This is a more general condition than the single sinusoidal input signal used earlier. In accordance with the theoretical results, the magnitude of the spectral distortion is computed for a pair of varied frequencies, considering the corresponding coefficient of variation of interpulse intervals. Results show that the distortion could be nonnegligible under practical values of the coefficient of variation. Such distortion may well affect the spectral structure in the wide frequency range. This study suggests that the spectral structure of HRV should be interpreted carefully, taking the above distortion properties into account, even though the IPFM model appears to be established as a mechanism mediating between autonomic input and heart rate variability.