Random Noise and Coherent Interference Estimation of MT Instrument

Random noise and coherent interference are major factors determine the performance of MT instrument. Based on auto and cross power spectrum of channels inside MT instrument, procedure is developed to estimate noise and coherent interference inside MT instrument. At first, short circuited input is applied to all channels of MT instrument. Coherent interference inside instrument is estimated by signal to noise ratio (SNR) of arbitrary two channels. Secondly, all channels of instrument are connected to same random noise input. Random noise inside instrument is estimated by noise spectrum of arbitrary two channels. MTU-5P of system 2000 is used for experiment. Experiment result shows that coherent interference, which is about 8 times random noise, exist in TS5 data; normalized power spectrum density of white noise is below -150 dB; it shows excellent performance in wide frequency band, but coherence interference in some band need to be minimized.