Constant fraction discriminator

About: Constant fraction discriminator is a research topic. Over the lifetime, 407 publications have been published within this topic receiving 3727 citations.

Multichannel time-resolved optical tomographic imaging system

Abstract: A time-resolved optical imaging system using near-infrared light has been developed. The system had three pulsed light sources and total 64 channels of detection, working simultaneously for acquisition of the time-resolved data of the pulsed light transmitted through scattering media like biological tissues. The light sources were provided by high power picosecond pulsed diode lasers, and optical switches directed one of the light sources to the object through an optical fiber. The light signals reemitted from the surface of the object were collected by optical fibers, and transmitted to a time-resolved detecting system. Each of the detecting channels consisted of an optical attenuator, a fast photomultiplier, and a time-correlated single photon counting circuit which contained a miniaturized constant fraction discriminator/time-to-amplitude converter module, and a signal acquisition unit with an A/D converter. The performance and potentiality of the imaging system have been examined by the image reconstruction from the measured data using solid phantoms.

The Delay-Lock Discriminator-An Optimum Tracking Device

Abstract: The delay-lock discriminator described in this paper is a statistically optimum device for the measurement of the delay between two correlated waveforms. This new device seems to have important potential in tracking targets and measuring distance, depth, or altitude. It operates by comparing the transmitted and reflected versions of a wide-bandwidth, random signal. The discriminator is superior to FM radars in that it can operate at lower power levels; it avoids the so-called "fixed error," and it is free of much of the ambiguity inherent in such periodically modulated systems. It can also operate as a tracking interferometer. The discriminator is a nonlinear feedback system and can be thought of as employing a form of cross-correlation along with feedback. The basic theory of operation is presented, and a comparison is made with the phase-lock FM discriminator. Variations of performance with respect to signal spectrum choice, target velocity, and signal and interference power levels are discussed quantitatively. The nonlinear, "lock-on" transient and the threshold behavior of the discriminator are described. Performance relations are given for tracking both passive and actively transmitting targets. Results of some experimental measurements made on a laboratory version of the discriminator are presented.

An oversampling delta-sigma frequency discriminator

Abstract: A circuit technique for performing oversampled A/D conversion on the phase/frequency information of an angle modulated signal is presented. It is shown that the technique is equivalent to a classic delta-sigma data conversion with instantaneous frequency as the input variable. Details of first and second-order implementations of the technique are presented, and suitability of the technique is discussed for applications such as in the rapidly evolving personal communications field. The most immediate application will be at the IF stage of a receiver where the discriminator input signal is bandlimited by the IF filter, and where sufficient amplification has occurred to provide the input signal levels required by the discriminator. >