US 20040179429A1
(19) United States
(12) Patent Application Publication (io) Pub. No.: US 2004/0179429 Al
Preston (43) Pub. Date: Sep. 16,2004
(54) METHOD FOR HIGH-PASS FILTERING FOR ECHO PROCESSING IN TIME OF FLIGHT RANGING SYSTEMS
(75) Inventor: Nigel Ashley Preston, Peterborough (CA)
Correspondence Address:
TOWNSEND AND TOWNSEND AND CREW,
LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO, CA 94111-3834 (US)
(73) Assignee: Siemens Milltronics Process Instruments Inc., Peterborough (CA)
(21) Appl. No.: 10/674,870
(22) Filed: Sep. 29, 2003
(30) Foreign Application Priority Data
Sep. 27, 2002 (CA) 2,405,658
Publication Classification
(51) Int. CI.7 G01S 15 00
(52) U.S. CI 367/99
(57) ABSTRACT
A method and system for high-pass filtering to remove DC and/or low frequency components of a receive signal from the transducer of a level measurement system. In one embodiment, the method includes generating a maximum signal profile and a minimum signal profile for the receive signal, generating a midpoint reference signal from the maximum and minimum signal profiles and subtracting the midpoint reference signal from the receive signal to produce a filtered signal.
