Journal of Radio Electronics. eISSN 1684-1719. 2025. №10
Full text in Russian (pdf)
DOI: https://doi.org/10.30898/1684-1719.2025.10.14
with a zero autocorrelation zone
to improve the quality of images
of space objects in inverse SARs
R.N. Ipanov
National Research University MPEI
111250, Russia, Moscow, Krasnokazarmennaya str., 14
The paper was received August 7, 2025.
Abstract. To obtain radar images of a set of small-sized space objects in near-Earth orbit or to resolve individual elements of complex space objects, the radar must have high spatial resolution. To achieve high resolution in slant range, complex (modulated) wide-band probing signals are used. The high angular resolution of small-sized space objects or elements of complex space objects is based on the inverse synthetic aperture effect. Among various classes of complex signals, three main types have found practical application in inverse SARs so far: linear frequency-modulated signals, stepped-frequency continuous wave signals, and phase-shift keying signals. On the interval of coherent accumulation of echo signals corresponding to the time of synthesis of the aperture of the inverse SAR, the total correlation characteristics of the ensemble of signals are analyzed. The presence of the total correlation noise of LFM and PSK signals affects the quality of the radar image. The use of orthogonal LFM and PSK signals allows for successful suppression of false signals from bright point targets in adjacent repetition periods. However, the high level of integral correlation noise in the cross-correlation function of orthogonal signals distorts radar images of weakly reflective surfaces located near bright extended objects. Therefore, signals with a zero autocorrelation zone are relevant for inverse SAR applications. In this work, a probe signal with a zero autocorrelation zone, which is resistant to Doppler frequency misalignment, is synthesized for inverse SAR. A comparative analysis of the total correlation characteristics of the synthesized ensemble of signals with the corresponding characteristics of orthogonal LFM and PSK signals, both without and with Doppler frequency misalignment, is conducted. In the Matlab software package, radar images of a complex space object were obtained using probing LFM and a signal with a zero autocorrelation zone. The advantage of a synthesized ensemble of signals over an ensemble of orthogonal LFM and PSK signals in terms of radar image quality has been substantiated.
Key words: ambiguity function, autocorrelation function, cross-correlation function, m-sequence, orthogonal signal, pulse train, recurrent interference, zero autocorrelation zone.
Financing: The reported study was funded by the Russian Science Foundation according to the research project № 23-19-00485, https://rscf.ru/project/23-19-00485/.
Corresponding author: Ipanov Roman Nikolaevich, iproman@ya.ru
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For citation:
Ipanov R.N. Application of probe signals with a zero autocorrelation zone to improve the quality of images of space objects in inverse SARS // Journal of Radio Electronics. – 2025. – №. 10. https://doi.org/10.30898/1684-1719.2025.10.14 (In Russian)