System for monitoring the walls of a borehole using a video camera

摘要

A borehole camera monitoring system comprises a camera head assembly adapted to be lowered into a borehole by means of a cable and control unit located above ground for generating a control signal for the operation of the camera. The camera head assembly comprises a fixed portion and a rotary portion containing the camera and associated equipment for examining the wall of the borehole. The fixed portion of the camera head assembly comprises a micro-controller for controlling the operation of the camera, a position encoder for detecting the angular rotation of the camera with respect to the fixed portion of the camera head assembly and a communication interface including means for multiplexing the video signal generated by the camera with an information signal generated by the micro-controller for transmission over the cable and means for extracting the control signal generated by the computer and transmitted over the cable. The control unit comprises, in addition to the above mentioned computer, a video monitor and a communication interface including means for extracting from the signal transmitted over the cable the video signal for the video monitor and the information signal for the computer and means for multiplexing the control signal of the computer for transmission over the cable. A depth counter is connected to the computer for detecting the depth of the camera head assembly from the upper edge of the borehole.