Limited-range seismic control system
AssigneeWestern Geophysical Company of America
InventorCarl H. Savit
Life of this patent
Estimating the term…
Abstract
A seismic exploration system includes a recording vehicle having a seismic cable connected thereto and one or more vibrator units. The seismic sensor cable includes at least one unterminated conductor. Operation of the vibrator units is programmed by transmitting, at very low frequency (VLF), a frequency-modulated, coded control-signal from the recording vehicle into the unterminated conductor. The conductor, acting as a VLF antenna, radiates a weak electrostatic E-field. A ferrite-core loop antenna on the vibrator unit detects the coded control signal, thereby to initiate the required vibrator operation. If desired, a reproduction of the seismic signal generated by the vibrator can be transmitted back to the recording truck over the same VLF radio link.
Claims26
A limited-range radio communications system for transmitting command and data signals between a seismic recording apparatus and at least one mobile unit having a seismic signal generator mounted thereon, said mobile unit being positioned adjacent to a desired line of survey and remotely from said recording apparatus, the system comprising;
- an unterminated, electrically floating conductor positioned on the earth's surface substantially parallel to the line of survey, for electrostatically radiating radio signals;
- first transceiver means associated with said recording apparatus and coupled to said floating conductor for transmitting coded command signals to and receiving data signals from said floating conductor;
- second transceiver means mounted on said mobile unit and having an antenna coupled thereto for receiving command radio signals from and for electromagnetically transmitting data radio signals to said floating conductor.
A limited-range radio communications system for transmitting command and data signals between a seismic recording apparatus and at least one mobile unit having a seismic signal generator mounted thereon, said mobile unit being positioned adjacent to a desired line of survey and remotely from said recording apparatus, the system comprising;
- an unterminated, electrically floating conductor positioned on the earth's surface substantially parallel to the line of survey, for electrostatically radiating radio signals;
- receiver means associated with said recording apparatus and coupled to said floating conductor for receiving data signals from said floating conductor.
- transmitter means mounted on said mobile unit and having an antenna coupled thereto for electromagnetically transmitting data radio signals to said floating conductor.
A limited-range radio communications system for transmitting command and data signals between a seismic recording apparatus and at least one mobile unit having a seismic signal generator mounted thereon, said mobile unit being positioned adjacent to a desired line of survey and remotely from said recording apparatus, the system comprising;
- an unterminated, electrically floating conductor positioned on the earth's surface substantially parallel to the line of survey, for electrostatically radiating radio signals;
- transmitter means associated with said recording apparatus and coupled to said floating conductor for transmitting command signals to said floating conductor;
- receiver means mounted on said mobile unit and having an antenna coupled thereto for receiving command radio signals from said floating conductor.
A seismic system having a short range communications system comprising:
- a seismic recording vehicle;
- a seismic cable connected to said seismic recording vehicle and adapted to extend from said vehicle for distances of at least one or two miles along a line of survey;
- means for detecting seismic signals connected to said seismic cable;
- mobile vehicle means for applying seismic signals into the earth at a plurality of successive stations adjacent said seismic cable along said line of survey;
- elongated antenna means embedded in said seismic cable and extending from said recording vehicle for most of the length of said seismic cable;
- first transceiver means in said recording vehicle for transmitting and receiving signals over said elongated antenna means;
- and
- second low power, short range transceiver means in said mobile vehicle means for receiving signals from and transmitting signals to said elongated antenna means.
Dependencies are inferred from the claim text.