An extended Frank code and new technique for implementing P3 and P4 codes

A method is presented for generating a class of polyphase pulse compression codes of length other than N² using an efficient digital implementation technique. The structure, called extended Frank (EF) code, can be applied to linear frequency-modulation waveforms for compression ratios of N×M where N and M are arbitrary integers. The phase matrix of the EF code has the same properties as that of the Frank code, but the restriction of identical numbers of columns and rows for the Frank code is removed. A special case N=κM, where κ is an integer, is discussed. The disadvantage of high sidelobes that results from the ED code is removed when P3 and P4 codes are implemented. By comparing the phase matrices of the P3 and P4 codes with the EF code, it is found that only (N-1) phase shifters are required to convert the EF code to P3 or P4 code. Hence, an effective implementing technique for the P3 or P4 polyphase code is obtained by using the simple EF code structure