Radar designers utilize long pulse with a specific goal to acquire high energy for detection of the targets at long ranges and resolution of short Pulse by modulation of the long Pulse is known as Pulse compression. Through frequency or phase coding of the large bandwidth of signal can be achieved. In this technique, the performance of radar for a given application demands good autocorrelation property – to maintain low sidelobe levels at the matched filter output. One of the essential kinds of coding is the biphase code. Because these codes are easy to implement. The condition for the goodness of the transmitted codes depends upon the peak sidelobe level at the output of the matched filter. In this project, we tend to describe the optimization of biphase codes of larger length so that a high compression ratio can be achieved. Though the barker codes are the well-known biphase codes these are available only for lengths upto13. It means with the help of barker code one can achieve the compression ratio only up to 13. Therefore, there is a need of searching higher length codes. In this work particle swarm optimization algorithm is used for the optimization of biphase codes up to 105. The results obtained are encouraging. For the code lengths, 60 to 64 the PSL = 4 and as length increases the results acquired are better. Further, the sidelobes are suppressed by designing a mismatched filter. It is shown that the sidelobes are appreciably at the cost of some signal-to-noise ratio.