Title:
SIGNAL DETECTION CIRCUIT
Document Type and Number:
Japanese Patent JPH04270594
Kind Code:
A
Abstract:
PURPOSE: To reduce the cost and to attain accurate discrimination by discriminating a tone pause time of an input signal digitally.
CONSTITUTION: Every time an EST signal 11 being a detection signal of an input signal is changed, a binary counter 1 is reset by an output of a D flip-flop 3 and implements count. When the signal input is consecutive till the result of count of the binary counter 1 overflows, an inverse of Q output of the D flip-flop 5 goes to a low level and the excess of the input signal over a discrimination time is informed externally by an inverse of IRQ signal 13.
More Like This:
Inventors:
MATSUSHIMA FUMIHIRO
Application Number:
JP5412091A
Publication Date:
September 25, 1992
Filing Date:
February 25, 1991
Export Citation:
Assignee:
NEC CORP
International Classes:
H04M11/00; H04Q1/30; H04Q1/45; (IPC1-7): H04M11/00; H04Q1/30; H04Q1/45
Attorney, Agent or Firm:
Masanori Fujimaki