Multi-channel ScanSAR mode realization in a space-based SAR

Аuthors

Bulygin M. L.^*, Markova A. S.^**, Mullov K. D.^***

Scientific Research Institute of Precision Instruments, 51, Str., Dekabristov, Moscow, 127490, Russia

*e-mail: Bulygin04@gmail.com
**e-mail: as.markova93@gmail.com
***e-mail: kmullov@gmail.com

Abstract

This paper discusses implementation of a space-based synthetic aperture radar (SAR) multi-channel ScanSAR mode. Employing the digital active electronically scanned array (AESA) allows forming a multi-beam pattern and implement high resolution multi-channel SAR modes. One option is implementation of the multi-channel ScanSAR mode.

Computation of imaging characteristics and SAR parameters are given for multi-channel ScanSAR mode. For example, using K = 4 antenna beams (channels) allows scanning M = 3 partial strips (total swath of 70.29 km, elevation angle of 40°) with a resolution of about 3.7 m. For single channel SAR system with aperture size 4 × 1.6 m resolution is 8 m.

SAR digital AESA was realized as a multi-segment antenna. Each segment is completely autonomous and allows form, transmit, receive and process signals. This architecture requires an exact synchronization of the segments with each other. Synchronous operation and management of all segments is ensured by the on-board processor.

Intersegmental time synchronization is realized as follows. For transmition synchronization in the samples of the linear frequency modulation probe signal, a linear phase shift is added. At the receiving point, delay filters are used to synchronize signals in each segment. These approaches allow increasing the synchronization accuracy by 20 times.

The presented synchronization methods are implemented employing high-speed field-programmable gate array. To create a fault-tolerant firmware realizing high-speed signal processing, it is necessary to account for the specific conditions of the on-board SAR equipment in space functioning. This requires selecting the appropriate hardware in the design of the SAR system.

Thus, the multichannel scanning mode employing allows improve significantly the radar imaging characteristics. Implementation of this mode requires solving the problem of an intersegmental synchronization of on-board equipment. At the same time, the on-board equipment and its firmware must meet the requirements of fault tolerance in space.

Keywords:

synthetic aperture radar, field-programmable gate array, digital signal processing

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