Acoustic waveform design for data transmission by using drill strings in logging-while-drilling

The logging-while-drilling (LWD) systems mainly use the mud-pulse telemetry to transmit the measured data from the bottom to the surface. Its transmission rate, however, is very low, which is a severe limitation for the real-time transmission. Recently, using the drill string as the transmission carrier draws people´s attentions and becomes one of the research focuses. In this paper, a waveform design scheme, which involves the baseband signal, carrier frequency and bandwidth consideration, is proposed for data transmission by using drill strings. As an example, the modulated raised cosine is studied in detail. This waveform matches the transfer property of the drill string, and has the potential to improve the transmission rate in LWD