A.A. Morozov1, T.P. Potapova2, N.V. Toporkov3, P.I. Puda4

1–4 JSC «Kaluga Scientific Research Radio Engineering Institute» (Zhukov of Kaluga Region, Russia)

At present, a considerable number of SAM radars are capable to operate with low probability of intercept (LPI) of transmission.

Detection of LPI transmissions is quite difficult either in time or frequency domain due to wideband modulation applied.

To intercept signals of such radars effectively airborne reconnaissance systems have to be equipped with super wideband low-noise digital sensors having at least two AESA receiver units with peak gain in each angular coverage sector.

To intercept and measure signal parameters of LPI radars sophisticated processing algorithms should be applied such as short time Fourier transform (STFT), time-frequency expansion specially designed to recognize various modulation patterns applied in LPI radars. These approaches should be implemented in parallel using a neural network trained on signals of various LPI radars.

The mentioned algorithms have not been elaborated entirely yet, and thus cannot be fully implemented in airborne sensors as they require rather considerable computing resources and higher data throughput capabilities.

As one of approaches to intercept LPI radar transmissions (when only their operating frequency range is generally known) we suggest to employ cross correlated processing of transmissions intercepted by spaced apart AESA receiving units that use multiple beams to scan synchronously coverage sectors in consecutive manner and with their array gain determined by array dimensions w.r.t. particular airborne platform.

We obtained results of math simulation on accuracy of direction finding of an emitter based on cross-correlation processing which show that RMS of LPI direction finding is considerably smaller than the same for a conventional radar signal is. Cross-correlated time-difference direction finding makes it possible to obtain bearing coordinates of an LPI emitter even for lower SNR ratios. After integration and comparison with angular and space parameters of known emitters, the obtained coordinates may have use for initial intercept of LPI radars.

Morozov A.A., Potapova T.P., Toporkov N.V., Puda P.I. Direction finding of LPI emitters using cross correlation processing
of signals intercepted with spaced apart receiving units. Radioengineering. 2022. V. 86. № 11. P. 21−27.
DOI: https://doi.org/10.18127/j00338486-202211-04 (in Russian)

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