Research And Application Of Pulse - Star Coherent Cancellation Technology Based On

Pulsar radiation of electromagnetic wave in the process of transmission, due to the interference of the interstellar medium, different frequency of electromagnetic wave of delay after the interstellar medium is different, can let see outline broadening of pulsars, and influence of the pulsar observation, so in the pulsar observations are usually coherent de-dispersion processing. De-dispersion was divided into two ways, one is coherent de-dispersion, dispel the dispersion by means of software process, another is non coherent de-dispersion, by way of group delay signal filter remove dispersion. Coherent de-dispersion can completely remove dispersion, but the need for a large number of floating point calculation. With the improvement of A/D sampling chip clock work and the development of the digital circuit technology, can be at a higher frequency and bandwidth will digitize analog signal, using the original data of disk storage for a long time, and then carries on the post-processing is very difficult, so urgent need for real-time processing.The main research contents and results are as follows:First, the realization of the pulsar observation system based on CPU using software processing, decoding, coherent de-dispersion, polarization detection, folding data, output psrfits file through mark5B data of observation, can display the pulse contour map of stars.In second, decoding, polarization detection, folding by using CUDA multi thread technology, the system most time consuming part of coherent de-dispersion using CUDA Fourier transform library cufft. To improve the efficiency of the whole system, real-time pulsar observation system to realize the preparation conditions. According to the calculation results, the use of pulse PAZI command star common data processing software psrchive can view the output data of contour, in J0835-4510 in the 1 channel 2bit sampling bandwidth of 16MHz, the center frequency of 2206MHz, respectively, in the CPU architecture and GPU architecture under processing number Mark5B 10 seconds according to the obtained contour contour basically is the same, the signal-to-noise ratio can meet the requirements of the pulsar observation, proved by GPU real-time processing result is consistent with the requirements of.Third, and then analyzes the advantages and disadvantages of the algorithm under the GPU framework, how to choose the appropriate number of threads in the GPU framework, the achromatic process how to appropriate Fu Liye transform points, by reducing CPU-GPU transmission time, the most time consuming parts are optimized using CPU-GPU memory mapping technology. Discussion on the existing problems and the future work at the end of the article also carried out.This paper uses the GPU framework, decoding, coherent de-dispersion, polarization detection for Mark5B data processing, folding, folding of pulsar profile using the tempo2 prediction procedure, can output PSRFITS file format, you can also display the pulse contour map of stars. And before the Yunnan Observatory 40 meter radio telescope to achieve coherent dedispersion algorithm, can obtain more precise pulsar profile. In the observation of the pulsar observation is set to J0835-4510, the single channel,2bit sampling,16MHz bandwidth, center frequency of 2206MHz. On the second 8MB data real-time sampling, processing can be completed in 0.51 seconds, compared with the CPU system architecture, the coherent de dispersion efficiency improvement of at least 14 times in the decoding, folding, using CUD A multi threading technology, so that the efficiency of the whole system is improved by 9 times, for the real-time pulsar observation system ready the conditions.