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:
Feb. 18, 1986
Filed:
Oct. 06, 1983
Richard Brie, Paris, FR;
Loic B Guidoux, Garancieres, FR;
Radioelectriques et 501 Telecommunications, Paris, FR;
Abstract
An echo canceller used in a data transmission modem for cancelling in the baseband signal of the receive path an echo signal .epsilon.(t) produced by the data signal from the transmit path. The echo canceller comprises a difference circuit for forming the difference between the signal from the receive path s(t)+.epsilon.(t) and a synthetic echo copy signal .epsilon.(t). The echo copy signal is formed by at least one transversal filter which operates at a sampling frequency equal to the frequency of the data and whose coefficients are adjusted to minimize the mean-square value of an error signal. This error signal e(n) at an actual sampling instant n of the filter is determined by forming the difference between the value of the output signal of the difference circuit at the instant n and the value of this signal at the preceding sampling instant (n-1), which has been multiplied by the ratio between the value of the data recovered at the instant n and the value of the data recovered at the instant (n-1). Also provided is a circuit for providing an error signal for controlling the filter coefficients as a function of the sign of the difference circuit out signals for the actual and previous sampling instants.