Tetra Tech, Inc.

Other

Honeywell G.m.b.h.

Henri Hodara

Steve W Braun

Steven W Braun

Willard H Wells

A distributed geophone data acquisition system is disclosed that includes a receiver for the geophone data and a plurality of data cables connected together and to the receiver at one end. The cables have a plurality of twisted pairs of electrical conductor channels and two fiber optic light guides. Multiple geophone takeouts are connected to separate channels of the cables. Remote data units are connected between adjacent ends of each data cable that convert the geophone signals on each channel to light signals for transmitting through the fiber optic light guide of the next cable to the next remote data unit and ultimately to the receiver.

Fiber optic seismic system

A pair of connectors that convert electrical signals into optical signals for transmission along an optic fiber, and that also convert optical signals received from an optic fiber into electrical signals, is combined with a two-optic-fiber cable to provide an interconnecting cable assembly that receives electrical signals from a sending apparatus at either end of the cable, and presents electrical signals to a receiving apparatus at the other end of the cable, although the intervening transmission is optical. One optic fiber optically links the electrical-to-optical converter (light emitter) in one connector to the optical-to-electrical converter (light detector) in the second connector, while the other optic fiber optically links the emitter in the second connector to the detector in the first connector; thus the cable assembly is bidirectional and may be laid down and connected in either orientation with equivalent performance. Preamplification and buffering is provided within each connector, for the optical-to-electrical conversion. Simple, easy to use, but very accurate alignment devices for juxtaposing the optical fibers to the sources and detectors permit rapid but reliable replacement of the cable. Such cable assemblies are advantageous in collecting data for seismic geomapping for petroleum, particularly when electrical wires too are in the cable assembly.

Bidirectional optical electronic converting connector with integral

This security system monitors a remote intrusion-sensing unit by probing it with a probe signal that is randomly modulated. The intrusion-sensing unit replies with a composite signal in which 'secure' or 'alarm' status information is superimposed on the random modulation of the probe signal. (The system may if desired be elaborated to accept and utilize other status information, such as 'access' or 'reverse correlation.') A master unit checks the correlation of the reply-signal modulation with the probe-signal modulation, and generates a special 'deception' alarm if the correlation is not in accordance with an established pattern--such as positive correlation, reverse correlation, or correlation varying in some way that is systematic or otherwise determinable by the master unit. For example, the correlation requirement may be controlled by a code that is generated (even randomly) at the intrusion sensor; or the correlation check may be made insensitive to yet further superimposed variations in signal level, frequency, or delay. Such further variations may, for instance, convey specific information about conditions at the remote secured facility--such as motion, sound or vibration there. Preferably the signals in both directions are optical signals transmitted by optic fibers. To make deception as difficult as possible (at least in the context of field operations) even for an intruder who knows exactly how the system works, the probe signal is of very low amplitude and the reply signal of very high amplitude.

Security system with randomly modulated probe signal

A transparent continuous optical fiber is embedded in a transparent panel made of glass or plastic, with the two ends of the fiber accessible from outside the panel for coupling to a visible or invisible light source and detector respectively. By nearly matching the refractive indices of the panel and the fiber, and using good-quality material for the fiber so that it does not scatter significant amounts of the light passing through it, the fiber can be made virtually invisible although it establishes a complete light circuit. Cutting or breaking through the panel at a point intersecting the fiber interrupts the light circuit and triggers an alarm.

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Altadena, CA, United States of America

Henri Hodara