Abstract: A sensor monitoring system comprises a passive sensor, a monitored transmitter, a repeater, and a central receiver. The system provides easy installation, convenient calibration, and very low maintenance. The sensor and the monitored transmitter are battery powered and, in order the conserve battery power, the sensor and the monitored transmitter receive power only on command from their respective microprocessor.

Abstract: A tank level monitoring and alarm system comprises a passive level switch, a transmitter, a repeater, and a receiver. It provides easy installation, convenient calibration, and very low maintenance. A mechanical level switch for the specific vessel is installed. The contacts of the level switch are connected to the transmitter. When the switch is activated, the transmitter immediately broadcasts an alarm signal to the receiver. A relay output at the receiver is either opened or closed thus activating the alarm or other device attached to it. The relay output may also connect to a control apparatus, such as a signal transmitter to provide for remote operation of such devices as valves.

Abstract: The present invention relates to a fluid detection system which can be adapted for use in applications including liquid-level detection, pipeflow monitoring, and interstitial leakage in double-walled containers. The system operates on principles of optics and provides the capability of remotely differentiating between fluids having different refractive indices including liquids and vapors. The present detector uses a unique light pulsation technique which increases permissible operating ranges over existing optical detection systems.