Clock synchronization over fiber

摘要

The present disclosure relates methods and apparatus for conducting a seismic survey using a fiber optic network. The method may include synchronizing a plurality of seismic devices over a fiber optic network where at least one of the seismic devices is separated from a master clock by at least one other seismic device. The method may also include encoding the master clock signal, transmitting the encoded master clock signal, and recovering the master clock signal. The apparatus may include a fiber optic network with seismic devices. The seismic devices may be arranged in a linear or tree topology.

主权项

1. A method of conducting a seismic survey, comprising:
synchronizing a plurality of seismic devices over a fiber optic network using a recovered master clock signal, wherein at least one of the seismic devices is separated from a master clock by at least one other of the seismic devices, wherein the master clock and the plurality of seismic devices are arranged in at least one of: (i) a linear topology and (ii) a tree topology; encoding the master clock signal in a data stream along with at least one of i) a signal containing seismic data, and 2) a signal containing command and control information, the data stream comprising at least one of a 4B5B bit stream and a 8B10B bit stream; transmitting the data stream directly to one of the at least one other of the seismic devices; and propagating the master clock signal to the at least one of the seismic devices through subsequent seismic devices of the at least one other of the seismic devices by performing at each subsequent seismic device:
recovering the master clock signal from a received data stream at the subsequent device;locking a local clock at the subsequent device to the master clock with the recovered master clock signal using a locking circuit;encoding the local clock signal as the master clock signal in a data stream, the data stream comprising at least one of a 4B5B bit stream and a 8B10B bit stream; and transmitting the data stream directly to at least one subsequent seismic devices.