A TECHNIQUE FOR MEASURING COORDINATES OF MOVABLE OBJECTS BY VIDEO PULSE RADARS

摘要

A measuring system consisting of several spatially-separated receiving sites and a transmitter radiating video pulse signals is analyzed. The aim is to develop an efficient algorithm for processing signals of multi-position monitoring system operating under conditions of correlated noise intended for online detection of movable objects hidden behind optically opaque obstacles. In the system, the hyperbolic (range-difference) technique is used to measure the target coordinates. Because of multiple re-reflections of the sounding signal from the room walls and indoor objects, the useful signal from a target is not identified by direct methods. For this reason, a procedure of suppression of the interference reflections of the sounding signal has been developed. Accumulation of the signal and elimination of interference noise from it is performed in real time through subtracting interlaced samples of the observed process from the signals of each receiving site on the assumption that the displacement of the object during a single scan is small. The magnitude of the signal peak-factor has been selected as a criterion for estimating time delay of the probe signal on the way from the transmitter to a target and from target to each of the receivers. The same criterion is used for rejecting the noise-affected rows in radar images of the target trajectory. A fast algorithm has been developed that, with a comparatively high signal-to-noise ratio, enables using the signal peak-factor as a criterion for rejecting the noise-affected rows in radar images and performing continuous processing of the observing system signals with representation in a user-friendly form. The continuity of measuring time delays of the signals propagating from a target to each of the receiving sites is provided by a polynomial approximation of the object motion trajectory. The high power characteristics of the monitoring system, stability of its parameters during measurement sessions and high accuracy of reproducing the reflected signal waveform have made it possible to use methods of digital signal processing in real time. The results of simulations are supported by the data that were accumulated and averaged over series of similar experiments.