Abstract: A power saving system and method for the analog-to-digital converter stage in a time of flight ranging system. A receiving echo signal having an envelope is converted into a digital form suitable for further processing by sampling the received echo signal envelope at precise intervals to obtain amplitude measurement points. An interpolation function is applied between each pair of adjacent amplitude measurement points. The application of the interpolation function provides a closer approximation of the shape of the received echo signal envelope without the need to use higher sampling rates which means slower analog-to-digital converters may be utilized resulting in power and cost savings.

Abstract: An antenna assembly suitable for use with a microwave-based level measurement system mounted on a vessel. The antenna assembly includes an installation thread, a shielded extension, and a rod antenna. The antenna assembly is screwed into a threaded portion in the opening of the vessel. The antenna assembly may be formed as a single integral unit molded from a polymer material. The antenna assembly may also be constructed with the installation thread, the shielded extension and the rod antenna comprising individual polymeric components which are welded together to form a unitary assembly. The polymer material is selected based on chemical resistant properties according to the application.

Abstract: A pulse-echo ranging system is described employing a microwave transducer head (100) providing an echo profile output signal which is largely compatible with receivers (204) and echo processing systems (206) designed for acoustic transducers. The transducer head employs novel microwave pulse generators (20a, 20b) each utilizing a microwave cavity (20a, 20b) excited by an avalanche discharge through a small signal diode (D2a, D2b) initiated by avalanche of a driver transistor (TR1a, TR1b) by a trigger pulse. Repeated pulse from one generator (2a) are transmitted by an antenna (12) towards a target, and return are mixed with pulses from the second generator (26) which are subject to a progressively swept delay relative to the transmitter pulses. The mixer output is applied to a tuned amplified (110) to extract components at an alias frequency related to the sweep rate of the delay relative to the transmitter frequency. The aliased signal is passed to a receiver (204) and echo processing system (206).

Abstract: An envelope detector for detecting the envelope of an input signal. The envelope detector includes an inverter for inverting the input signal and two offsetting circuits for offsetting the input signal and the inverted input signal so as to align the peaks of the signals with zero volts. The two offset signals are then summed, which results in a signal proportional to the inverted envelope of the input signal.

Abstract: A method of measuring the position of a target feature in a pulse-echo ranging system including transmitting at least one pulse of high frequency energy from a transducer towards the target feature, receiving energy reflected back from the direction of the target feature to the transducer to provide at least one return signal, repeatedly sampling the amplitude of the return signal(s) at intervals to form a digital database relating signal amplitude to elapsed time, and searching the database for at least one target zone in which a greater than background rate of fall of the return signal amplitude is sustained.