Demodulation of acoustic telemetry binary phase shift keying signal based on high-order Duffing system

Abstract

In order to grasp the downhole situation immediately, logging while drilling (LWD) technology is adopted. One of the LWD technologies, called acoustic telemetry, can be successfully applied to modern drilling. It is critical for acoustic telemetry technology that the signal is successfully transmitted to the ground. In this paper, binary phase shift keying (BPSK) is used to modulate carrier waves for the transmission and a new BPSK demodulation scheme based on Duffing chaos is investigated. Firstly, a high-order system is given in order to enhance the signal detection capability and it is realized through building a virtual circuit using an electronic workbench (EWB). Secondly, a new BPSK demodulation scheme is proposed based on the intermittent chaos phenomena of the new Duffing system. Finally, a system variable crossing zero-point equidistance method is proposed to obtain the phase difference between the system and the BPSK signal. Then it is determined that the digital signal transmitted from the bottom of the well is '0' or '1'. The simulation results show that the demodulation method is feasible.

Weak wide-band signal detection method based on small-scale periodic state of Duffing oscillator

“…Using the conventional Duffing oscillator detection method which is based on a strong reference signal, a weak periodic signal buried in noise can be detected via the phase transition from chaos to large-scale periodic motion. [27] However, there are several inherent deficiencies in the conventional Duffing oscillator detection method.…”

A Novel Weak Signal Detection Method of Electromagnetic LWD Based on a Duffing Oscillator

“…Accurate drilling information determines the correct directional drilling variables and geological formation from the wellbore to improve drilling efficiency [1,2]. Drilling signal pulses experience unpredictable and complex adjustable signal impairments caused by friction between drill bit and stratum formation, drill string vibration noises, signal attenuation and drilling fluid circulations, high temperature, and high pressure of the downhole environment [3][4][5][6]. The impact leads to profound signal disruption and noise sources at the surface measurement system, resulting in surface signal detection complexity.…”