Pulsed Signal Duration Shaper with Adaptive Response Thresholds

Abstract

His paper represents a shaper designed to restore the width of rectangular pulses transmitted over an open-optic (wireless) communication channel and having shape distortions in the form of amplitude modulation, pedestal and tightening of the front and decay. The principle of pulse width recovery is based on the formation of voltage comparator thresholds adaptive to changes in high and low pulse signal levels. Due to the use of sample-and-hold circuit (UVH - S/H circuit) in the circuit, the values of the input signal levels are stored in the previous half-periods. The threshold voltage of the comparator before its operation is formed as the output voltage of a resistive voltage divider into two inputs, one of which is supplied with the current voltage of the input signal, and the other with the voltage level of the signal recorded in the S/H circuit at the previous half-cycle of information pulses. The study presents the method for estimated error in pulse width formation from comparator bias voltages, S/H circuit and modulation changes in the shape of the information signal. The example provides quantitative estimates of the error. In the Micro Cap circuit modeling environment, a model experiment was performed, diagrams of the signal source and shaper models on ideal components and time diagrams of the device operation are presented. The operability of the device during the passage of a pulse signal with the above-mentioned shape distortions has been confirmed. A large depth of modulation of the input signal amplitude is allowed. The formative properties of the circuit are provided. The speed of the shaper is determined by the speed of the comparator and the S/H circuit. To reduce the error of the duration forming of information pulse signals, it is necessary to choose a voltage comparator and sample-and-hold circuit devices with minimal static errors.