Abstract: A method for synchronizing a clock in a device at the Earth's surface with a device disposed in a wellbore includes generating a time datum for a signal generated at at least one of the surface and in the wellbore proximate an end of the pipe string. A time delay is determined between detection of the signal at the at least one repeater and retransmission of the signal from the at least one repeater. The time datum is appended with a signal corresponding to the time delay. The retransmitted signal is detected at the other of proximate the end of the pipe string and at the surface.

Abstract: Methods and apparatus to configure drillstring communications are described. In one disclosed example, a method to configure drillstring communications involves generating a signal at a transmitter coupled to a drillstring, transmitting the generated signal via the transmitter to a receiver, sampling the transmitted signal at the receiver to generate a received signal, calculating a transmission characteristic based on a comparison of the generated signal and the received signal, and configuring at least one of the transmitter or receiver based on the transmission characteristic.

Abstract: Method for decoding a signal sent over a bandwidth-expanding communication system, where both channel estimation and signal detection are carried out on a set of samples generated by sampling the received signal at a sub-Nyquist rate, thus allowing for a significant reduction of the complexity of the sampling device of receivers using said method, as well as a significant reduction of their computational requirements.