The Realization Of The Spectral Lines Agile Observation Terminal And The Research Of Its Calibration Method

The 40 meter radio telescope of the Yunnan Astronomical Observatory of the Chinese Academy of Sciences is an important radio astronomy observation and research platform in China.Because the existing observation terminal is complicated in the frequency switching of the radio astronomical line,and the observed bandwidth of the radio astronomical line is relatively wide,it is not conducive to narrow-band observation of the radio astronomical line.So this thesis proposes a receiver design based on agile transceiver.The solution is based on an on-chip system that can be programmed online and narrow-band high-precision sampling.The analog front-end circuit can change parameters such as local oscillator frequency and filter bandwidth under program control to realize a high-Q programmable filter to select narrow-band signals.This eliminates the need for high-speed and low-accuracy ADCs for high-precision,short-time sampling in a narrow time window.This scheme is suitable for the refinement of narrow-band spectral line observation in radio astronomy.Since the local oscillator frequency can be flexibly adjusted,fast frequency switching calibration can be performed for this system.The main work done in this thesis is:1.In this thesis,a set of radio astronomical molecular line narrow-band observation terminals is designed based on agile transceiver,which realizes high-precision structure observation of multiple radio astronomical molecular lines.When the frequency resolution reaches 1 kHz,the XFFTS terminal need 5 million points,the ROACH-2 terminal need 500 thousand points,the terminal only needs 256 points.Terminal performance is much higher than other terminals.2.The Shanghai Astronomical Observatory uses a TM65-meter radio telescope to observe the frequency resolution of the methanol maser line at 1.4 kHz.The Arecibo observatory uses a 305-meter radio telescope receiver to observe neutral hydrogen at a frequency resolution of 11.72kHz.Based on this terminal,methanol maser spectral line of W3(OH)source was observed under the 40-meter radio telescope of Yunnan Astronomical Observatory and the neutral hydrogen spectral line in the galaxy was observed under the science popularization telescope.The frequency resolutions were 0.976 kHz and 0.122 kHz,respectively.The results show that the spectral lines observed in this thesis are more detailed and have higher frequency resolution.3.In order to perform fast frequency switching calibration on the radio astronomical molecular line,a fast frequency switching calibration terminal based on agile transceiver is realized.Finally,the neutral hydrogen line was calibrated under this terminal.The main innovations of this thesis are:This thesis first proposes the use of agile transceiving scheme for the observation of radio astronomical line,which is especially suitable for narrow-band observation of radio astronomical spectral lines.This thesis presents a frequency switching calibration method based on the agile transceiver platform.Under this terminal,the frequency switching calibration can be completed quickly.The frequency switching time is within 1s.