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:
Mar. 13, 1984
Filed:
Jan. 27, 1982
David W Petr, Red Bank, NJ (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
An ADPCM coder (100) converts a linear PCM input signal representative of PCM encoded speech or voiceband data into a quantized n-bit differential PCM output signal. Samples of the PCM input signal are delivered to a difference circuit (11) along with a signal estimate of the same derived from an adaptive predictor (12). The resultant difference signal is coupled to the input of a dynamic locking quantizer (DLQ). A quantized version of the difference signal is delivered from the output of said quantizer to an algebraic adder (17) where it is algebraically added with the signal estimate. The result of this addition is coupled to the input of the adaptive predictor, which in response thereto serves to generate the next signal estimate for comparison with next PCM sample. The adaptive quantizer has two speeds of adaptation, namely, a fast speed of adaptation when the input linear PCM signal represents speech and a very slow (almost constant) speed of adaptation for PCM encoded voiceband data or tone signals. The decoder (101) operation is essentially the inverse of the coder, and similarly has two speeds of adaptation.