Research of the M-sequence Autocorrelation Function Side Lobe Suppression Due to the Cyclic Accumulation

For the purpose of acquiring high detailed images using satellite or airborne synthetic aperture radars (SARs) phased coded waveforms are used. This approach allows SAR to obtain high resolution images with high signal to noise ratio. The main downside of this approach is high side lobe level which appears in the form of rows of the bright dashes, arranged around single or complex target response codirectional with Range axis. This effect essentially deteriorates the quality of image visual analysis by the human eye and substantively reduces the capabilities of the automatic image processing techniques. For that cause many different methods exists that reduce side lobe level with different trade-offs. One of this methods is application of the circular shifts of the binary sequences. It cyclically shifts each emitted sequence while accumulating autocorrelation function for each subsequent shift. For effective usage of this method optimal circular shift parameters must be found which includes, as the main parameter, circular shift step or overall number of autocorrelation function accumulations. This paper presents the analytical research into M-sequence autocorrelation function side lobe suppression due to the cyclic accumulation.