TWO-CONDUCTOR BIDIRECTIONAL DIGITAL SEISMIC TELEMETRY INTERFACE

摘要

A two-conductor bidirectional digital telemetry interface between a seismic sensor acquisition/conversion module (40) and a seismic data collection module (20). The data collection module is configured as a master electronics device and the sensor acquisition/conversion module is configured as a slave electronics device in the telemetry system. The master device provides power to the slave device over the two conductors (36). The master device transmits portions of a digital seismic data packet to the master at a different second time in a fixed-duration frame. The frames are transmitted at regular intervals. The outbound commands and inbound data are encoded by block codes. A phase-locked loop (54) in the slave is locked to a master clock (35) in the master by deriving a clock and a sync point from the block-coded commands it receives from the master. The block code representing each command bit minimizes dc drift and provides a level transition in the command that can be used to maintain synchronism between master and slave.