The 40m radio telescope of YNAO was built from 2004 and finished on May. 21th, 2006, and began to carry out the observation from then. The aims of the construction are to receive the downlink scientific data of CLEP and use the astronomical measure method to determine the orbit of CE-1. As the second largest radio telescope in China, we have been considering how to use it on radio astronomical observation researches, such as international VLBI observations and single dish pulsar observations, etc. In this Ph.D. thesis, we use the VLBI terminal to do the observations on some high flux pulsars, then we do the software coherent de-dispersion to the data. The results are obtained as follows: For pulsar Vela(PSR J0835-4510), we had done several long time observations. First we fold the time domain data with the sight period and get the mean pulsar profiles, and we find the variety rate of its period is very quick which is specifically showed on the broaden half-width of mean pulsar profile. For the pulsars whose DM are very small, like PSR 0332+5434, we obtain the profiles by folding the data in the single channel. Compared to the coherent de-dispersion method, the difference of the two methods is not significant(1-2). Considering the parameters of the telescope and the using VLBI terminal, the smallest sensitivity of 40m radio telescope is 16.8mJy. The flux of pulsars in L band is basically in the range of 0.1-1mJy, but the receiver of 40m radio telescope works at S and X band. The pulsars emit on the whole radio band, and the spectrum index is between -1.6 and -1.8 in S band. Now we use the S band receiver to receive the radio emission of pulsars, while the flux decreases in this band. Therefore, we are need to raise the bandwidth and integration time to increase the SNR and the sensitivity of the system. Finally, we have made a prospect to the research topics of this field in the future. Considering our present research status, a long-term project is proposed.
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