Design And Research On Electromagnetic Radiation Measurement System Of EHV Transmission Line Based On Dual Channel

With the development of science and technology, environment effect about electromagnetic radiation of high voltage transmission lines has caused extensive concern. Accurate measurement of radio interference yet becomes a key part of environment evaluation of electromagnet radiation, but in actual operation, the value of background noise usually higher than the National standard’s. The main reason is the effect of Co-channel Interference. So, in order to Suppress Co-channel Interference, adaptive offset technologies on the basis of LMS are applied.Dual channel Measuring Receiver system is proposed in this paper to overcome time out of phase in single channel systems. The three parts of the system are measurement antenna, Dual channel measurement receiver and PC. Two antennas are placed in front of tested device a certain distance and ten times of it, respectively. One of them receives mixed signals of the tested device and its background noise. And the other one has two functions; it receives background noise and filters them at same time in the least sum of squared errors by an adaptive filter. In that case, the background noise can be counteracted by a subtracter.The channel is composed by four modules:receiving, signal acquisition, data processing and data transmission. Chips are indispensable in these modules. Chip AD9548synchronizes clocks. D3839A, a Monolithic AM radio integrated chip, achieves high, mixing and intermediate frequency amplification. Dual channel synchronous data acquisition and processing are completed by one piece of ADSP21992, alternatively a computer, transmitted to through a USB connector.This paper mainly introduces principles of the system, designs of the module circuit and communication protocol of the interface, introduces the module simulation and debugging. AD9548, DSP, FPGA are debugged in this paper; the key parts of interface are illustrated by its waveform simulations. This design accomplishes data acquisition, processing and transmission, and works in measurement of high voltage transmission lines’electromagnetic radiation.