apparatus for removing noise from a signal channel in a borehole electromagnetic telemetry system, and for receiving data transmitted by an electromagnetic transmitter in a borehole in the presence of an electromagnetic noise source

摘要

"APPARATUS FOR REMOVING NOISE FROM A SIGNAL CHANNEL IN AN ELECTROMAGNETIC TROUBLESHOOTING SYSTEM AND FOR RECEIVING DATA TRANSMITTED BY AN ELECTROMAGNETIC TRANSMITTER, AND METHODS FOR REMOVING A NOISE TELEMETRY PROVIDE AN ELECTROMAGNETIC NOISE CHANNEL FOR AN ELECTROMAGNETIC SURVEILLANCE TELEMETRY SYSTEM ". An electromagnetic borehole telemetry system that provides the best signal-to-noise ratio is shown in figure 1. Adaptive filters (28) use noise channels as references to remove noise from the signal channel. Enhanced sensors (40) provide low signal noise channels. Motion sensors (42) are shielded against electromagnetic signals to prevent telemetry signal detection.