When the pulsar signal propagates in the interstellar medium(ISM), the high frequency and low frequency components of the signal reach the radio telescope with a certain delay. Therefore, the pulsar signal will appear energy dispersion, which will broaden the pulse profile, decrease the signal to noise ratio(SNR), and even lead to the disappearance of the pulse signal. In this paper, we analyze the sampling, polarization and arrangement of baseband data based on the coherent dedispersion algorithm for the problem of pulsar baseband data dedispersion. We systematically study the coherent dedispersion data processing procedure and test the pulse profile changes under different FFT block sizes. An optimal selection strategy of FFT block sizes is proposed for reducing the operation time and obtaining a better pulse profile. We propose two methods, one is the generation of ISM transfer function, the other is the pulsar period and phase prediction method at a certain time, and discuss integral and folding strategies. We test the algorithm based on the baseband data of CASPSR and Medusa terminals observed by Parkes 64m radio telescope, and analyze the reading and processing methods of baseband data of different terminals. The experimental results show that the pulse profile with SNR greater than 200 is obtained, which verifies the effectiveness of the algorithm.

Digital channelization decomposes a wideband signal into multiple adjacent sub-bands using Parallel Technology. Channelization can effectively reduce the pressure on the radio astronomy digital backends system and make wideband signal processing possible. Aiming at the problems of signal attenuation at sub-band edge, spectral leakage and aliasing encountered in wideband signal channelization, algorithms to reduce the problems are studied. We design a Critically Sampled Polyphase Filter Bank (CS-PFB) based on the Finite Impulse Response (FIR) digital filter with a Hamming Window and systematically analyse the frequency response characteristics of the CS-PFB. Based on the channelized structure of the CS-PFB, an oversampled polyphase filter bank (OS-PFB) is designed by data reuse, and the filtering frequency response characteristics of CS-PFB and OS-PFB are compared and analyzed. Using the wideband baseband data generated by the CASPSR backends of Parkes, we implement sub-band division and 16-band output of these data based on the 2× oversampling OS-PFB, and the problem of spectrum inversion in the sub-bands is corrected. After removing 25% of redundant data in the head and tail of each sub-band, we recombine the sub-bands into a wideband. The wideband signal is almost identical to the original observed signal. Therefore, the experimental results show that OS-PFB can eliminate signal attenuation at the sub-band edge, spectrum leakage and aliasing caused by channelization. For the 400MHz baseband data of J0437-4715, we compare the pulse profile obtained from the original baseband data with the pulse profile obtained after the channelization and recombination. The phase and amplitude information of the pulse profiles are consistent, which verifies the correctness of our channelization algorithm.