A continuous phase-frequency modulation technique and adaptive pump noise cancellation method of continuous-wave signal over mud telemetry channel.

• An effective modulation method for continuous wave telemetry is proposed. • The modulation equation of the CPFK signal is established. • An adaptive pump noise cancellation method is proposed based on PSO algorithm. • Simulation results validate the effectiveness of the proposed modulation method. Continuous wave telemetry is one of the critical downhole-to-surface transmission techniques of downhole information for logging while drilling (LWD). This paper aims to present a highly effective modulation technique for a continuous wave telemetry called Continuous Phase-Frequency Keying (CPFK) and an adaptive coherent detection method for the CPFK signal. The modulation equation of the CPFK signal is established according to the acceleration/deceleration time of the motor in a continuous wave generator, the coherent detection method is given for the demodulation of CPFK signal, and then the adaptive mud pump noise cancellation algorithm is proposed for identifying CPFK signals based on probability analysis and PSO (Particle Swarm Optimization) algorithm. The results of simulation analysis show that the proposed CPFK modulation mode is feasible and the adaptive mud pump noise cancellation algorithm can realize the demodulation and decoding of CPFK signals. It has been found from the analysis that pump noise is the main noise affecting the demodulation of CPFK signals, accurate removal of pump noise can effectively improve the frequency band utilization of CPFK signal and reduce the bit error probability of the adaptive mud pump noise cancellation algorithm. [ABSTRACT FROM AUTHOR]