Research On Monitoring Method And Equipment Of Radio Frequency Interference For Large Radio Telescopes

Radio astronomy use equipment with highest sensitivities to collect electromagnetic radiations from the universe. By analyzing these emitted signals, the physical information of celestial objects can be quested. Excellent site is an important guarantee for the completion of the scientific objectives and effective operation of radio telescope. The main factors for site of the radio telescopes include electromagnetic environment, hydrological, meteorological, geological conditions, isolation and accessibility, etc. Development of radio astronomical demands higher sensitivity data, an important factor is observed over wider frequency. With the continuous development of methods and techniques of astronomical observation,.radio astronomy demands more and more bands. However, with the continuous development of radio communication system, RFIs have become a curial factor. Data of RFIs will provide a basis for the development of the radio telescope receiver system, to find electromagnetic interference within the site, to protect the radio quiet zone.This dissertation is based on the work of RFI (Radio Frequency Interference) monitoring for those telescopes that are under construction and those are in the preparatory phase. Frequency allocation for Radio astronomy is briefly introduced, and reviews the some standard for Radio astronomy made by ITU, then Deduced interference threshold of typical telescope. About RFI monitoring on radio telescope have long been carried out in the world, SKA (Square Kilometer Array) have carried out two series at candidate site on 2003 and 2010. Discusses in detail on the noise temperature, sensitivity characteristic of monitoring equipment, Test task scheduling. It discusses the development of instrumentation, control and data processing method, and discusses how to establish a set of RFI monitoring equipment and test specifications (including software, hardware, data processing, etc.). Lots of campaigns have been carried out to find excellent electromagnetic environment for the telescope site and shows some data of RFIs.Because the radio telescope has a great reception area and excellent performance of receivers, so the interference threshold value made by ITU is high. RFI monitoring equipment has not yet reached threshold value that prescribed by ITU, need to develop a higher sensitivity RFI monitoring equipment. After continued sitting work, will get more and more RFI data, analyze and compare these data, as the basis for radio astronomical observations and electromagnetic environment protection.