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:
Jul. 09, 1996
Filed:
May. 27, 1994
Shrirang Jangi, Germantown, MD (US);
Jie Chen, North Potomac, MD (US);
Hughes Electronics, Los Angeles, CA (US);
Abstract
A DTMF digit detecting method and apparatus includes signal state identifier (32) for identifying whether the received signal is in a DTMF-digit-detect state, a no-detect high-energy state, or a no-detect low-energy state, digit candidate identification processor (34) for identifying a digit candidate when the presence of a state other than the no-detect low-energy state is detected following a detection of the presence of the no-detect low-energy state for a first predetermined period of time, digit identifier (32) for identifying a DTMF digit corresponding to a sample group in a DTMF-digit-detect state, and valid digit identifier (34) for identifying a valid DTMF digit when at least a first predetermined number of sample groups are all in the DTMF-digit-detect state or in an allowable combination of states. An allowable combination of states exists provided the following conditions are met: (1) at least half of the first predetermined number of sample groups are in the DTMF-digit-detect state and correspond to the same DTMF digit; (2) no two sequential sample groups are in a state other than the DTMF-digit-detect state; and (3) no two sequential sample groups in the DTMF-digit-detect state correspond to one or more DTMF digits other than the DTMF digit corresponding to at least half of the first predetermined number of sample groups.