The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 28, 1987
Filed:
Nov. 26, 1984
Mark R Magee, Saratoga, CA (US);
Richard E Saffran, Boston, MA (US);
GTE Government Systems Corporation, Stamford, CT (US);
Abstract
Drift of the standing wave pattern in an acoustic doppler intrusion detection system in a confined space is compensated by adjusting the relative radiating and receiving positions of the radiator and receiver transducers, respectively, either mechanically or electrically until the signal level of the carrier wave at the receiver transducer is optimized. In the mechanical adjustment mode, either the receiver transducer or the radiating transducer is supported for movement relative to the other and is moved by a motor energized under the control of a signal level sensor circuit connected to the output of the receiver transducer. In another mode, a plurality of receiver (or alternatively radiator) transducers are connected through a switch to the signal level sensor circuit which in response to a drop in received signal level below a predetermined threshold, selectively switches the active transducer to optimize the received signal level. In still another mode, one of at least two radiator (or alternatively, receiver) transducers is connected through a variable phase shifter to the signal generator (or to the receiver circuit for the receiver transducer), the phase shifter being adjustable in response to the output of the signal level sensor to optimize the signal level at the receiver transducer. The invention comprehends the apparatus for and method of optimizing signal strength at the receiver transducer.