PULSE COMPRESSION

PROBLEM TO BE SOLVED: To reduce unnecessary side lobe appearing before and after compressed pulse in pules compression with encoding used for transmission of radar, sonar, etc. SOLUTION: In pulse compression by encoding, when its sub pulse width is τ, conventional pulse compression codes are all to compress to one sub pulse width without limitation to phase change. Against this, in this case, code phase is rotated in the same direction so that a frequency spectral band width is concentrated in a zone with the width narrower than ±1/τ, and the resulting compression pulse is compressed to a plurality of the sub pulse widths. In this method, as the result of selection of a code system with smaller side lobe ratio, the side lobe ratio can be made smaller than the that of the above conventional method under the same compression ratio. Also, the band width of the compression pulse which was widened due to compression to the plurality of sub pulse widths becomes narrower than ±1/τ, but by setting the original sub pulse width smaller allowing for this band width expansion, the compression pulse width can be further reduced.