Improving the accuracy and performance speed of the digital spectral-correlation method for measuring delay in radio signals and direction finding

A promising direction for the development of passive radar monitoring stations is to improve their efficiency by increasing their speed of performance. For the digital spectral-correlation method for determining the delay of radio signals and direction finding, analytical expressions have been derived for a variance of the estimation of the delay in receiving a signal by radio channels and directions to the source of radio emission. A feature of the method reported in this study is the use of two-stage temporal and spatial spectral analysis of the mutual spectrum, a single-iteration correlation analysis. The duration of estimating the direction finding has been evaluated through the total number of multiplication operations with accumulation. The proposed method, while providing for a gain of 27 times in terms of performance speed, demonstrated a slight decrease in accuracy compared to the optimal one due to energy signal loss. The result of the simulation has established the dependences of the standard deviation in the direction finding and delay estimates on the signal-to-noise ratio, the type of spectral analysis window, and the size of the antenna base. The standard deviation of the direction-finding estimate depends on the signal-to-noise ratio and varies over the range of values[0.08; 0.034]° with a change in the signal/noise ratio[−10; 40]dB. As the signal/noise ratio increases, the error decreases in line with a hyperbolic dependence. The standard deviation of the delay estimate depends on the signal-to-noise ratio and varies similarly to the error of the directional estimate, and is in the range of values[18.176; 1.56]ns, which corresponds to an error of[0.637; 0.055]%. The error of direction-finding estimation, depending on the size of the antenna base, decreases in the exponent within[1.6; 0.03]° with an increase in the antenna base in the range from 200 to 7,500m. The results reported here could be used for the parametric optimization of spectral-correlation radio direction finders at passive radar monitoring stations.