Jie Chen

US Patent:

55352715, Jul 9, 1996

Filed:

May 27, 1994

Appl. No.:

8/250783

Inventors:

Shrirang Jangi - Germantown MD
Jie Chen - North Potomac MD

Assignee:

Hughes Electronics - Los Angeles CA

International Classification:

H04M 100

US Classification:

379351

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.

US Patent:

20170154181, Jun 1, 2017

Filed:

May 26, 2015

Appl. No.:

15/313785

Inventors:

- Washington DC, US
Jie CHEN - Arlington VA, US

International Classification:

G06F 21/55
G06F 21/85

Abstract:

A system detects a covert timing channel on a combinational structure or a memory structure. The system identifies the events behind conflicts, and constructs an event train based on those events. For combinational structures, the system detects recurrent burst patterns in the event train. The system determines that a covert timing channel exists on the combinational structure if a recurrent burst pattern is detected. For memory structures, the system detects oscillatory patterns in the event train. The system determines that a covert timing channel exists on the memory structure if an oscillatory pattern is detected.