Optical transmission of digital seismic data

Abstract

An optical fiber cable is used as the transmission medium for data and status signals from remote digital acquisition units to a master station of a distributed digital field system. Each digital acquisition unit has associated with it one or more sensors for sensing motion in an elastic body. The master station of the system also uses an optical fiber cable as the transmission medium for transmitting command signals to the digital acquisition units. The digital acquisition units, when first connected into the system, sense the master station signal and determine which direction to transmit. In normal operation, one digital acquisition unit receives the master station command and repeats the command to the next digital acquisition unit and so on. The digital acquisition units then reverse direction of transmission and reception, the data acquisition unit receiving from an adjacent digital acquisition unit and repeating data or status signals, then adding its own data or status signal onto the line before passing it to the next digital acquisition unit in the direction of the master station. The optical fiber cable transmission medium provides extremely high bandwidths permitting very high data rates and large numbers of channels and also provides complete immunity from electromagnetic radiation.