Research on signal processing of continuous wave mud pulse

The system of continuous wave mud pulse measurement is important for oilfield directional drilling well. The signal processing is one of the key technologies to the system of mud pulse measurement, however, it is difficult to acquire the useful signals, since including most of reflective and mud pump noises. Based on the signal´s characteristic of sine, a new difference filter method, which is in the time field, is put forward. The method combines with the band-pass filter, which is in the frequency field, to reject the noises. Costas phase-locked loop technology and number control oscillator have been used in decoding technology, which can demodulate phase information and decode the DBPSK signal. By the analyses in theory and experiment, the signal can be correctly decoded.