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:
May. 17, 1977
Filed:
Oct. 31, 1975
Krishnamoorthy Virupaksha, Brookeville, MD (US);
Communications Satellite Corporation (Comsat), Washington, DC (US);
Abstract
An echo canceller having a digital transversal filter with an adaptive control loop for achieving minimum echo is disclosed. Minimum echo is attained by subtracting a synthesized echo from the real echo, the synthesized echo being formed in a digital transversal filter by multiplying a stored replica of the impulse response times the incoming signal. The stored replica is updated using the steepest descent technique by adjusting each of the stages of the replica memory a given amount. The incoming signal is differential pulse code modulation encoded to reduce the process complexity and the size of the memories which store the replica and the incoming signals or, alternatively, increase the performance of the canceller.