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:
Nov. 20, 1990
Filed:
Apr. 12, 1989
Jurgen Lau, Weil am Rhein, DE;
Abstract
The filling level meter for measuring the filling level in a container includes a transmitting and a receiving arrangement which directs sonic or ultrasonic pulses onto the filling material surface and receives the backscattered pulses reflected by the filling material surface and converts them to electrical reception signals. Connected to the transmitting and receiving arrangement is an evaluating circuit which in a signal processing path generates an envelope signal corresponding to the envelope of the reception signals, digitizes sampled values of the envelope signal, stores in a memory the digitized sampled values for creating a distance-dependent or travel-time-dependent amplitude profile of the measurement distance and evaluates the amplitude profile for determining the travel time of the most probable useful echo signal. Parallel to the signal processing path for generating the envelope signal, in the evaluating circuit a frequency detection of the echo signals is carried out by which echo signals having the transmission frequency of the sonic or ultrasonic pulses are determined. In dependence upon the result of the frequency detection the signal processing path is opened only for the echo signals having a frequency corresponding to the transmission frequency. As a result all the reception signals having a frequency not corresponding to the transmission frequency are excluded from the digitizing and further processing. Due to the Doppler frequency shift these include all the reception signals which are caused by reflections at moving obstacles. On the other hand, all reception signals having a frequency identical to the transmission frequency are passed on unchanged for the digitizing and further signal processing.