Switching of seismic surveillance recorder - utilises seismic event while signal passes via shift register delay to recorder

摘要

During the continuous surveillance of seismic events of the ground adjacent to openings for liquid storage, the length of recording medium becomes excessive. This is reduced by switching the recorder from geophone signals and recording them after a delay so that no information is lost. A number of highly sensitive geophones (14) are connected by cable or radio to a control room where the signals are amplified, (21) and passed to a circuit (22) which switches on the recorder (24). This is effected by relay (28) when the signals exceed a certain threshold. The signals for recording enter a shift register (25) which provides sufficient delay for the recorder to switch on and advance the recording paper (26) at normal speed. A clock (27) provides time and date indications along the record.