Title:
TONE DISABLER DEVICE
Document Type and Number:
Japanese Patent JP3215788
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To reduce the required operation volume and the required memory capacity to make the device small-sized, low-cost, and low-power consumption in the case that the 2100Hz phase inverted answer tone of a wired modem of V25 series or the like is detected to generate the disable signal of an echo canceller or an echo suppressor.
SOLUTION: The answer tone is subjected to frequency conversion and orthogonal detection divisionally twice with 2kHz and 100Hz where processing is easy with a small memory capacity by 8kHz sampling, and thinning processing is performed by digital integration with reset requiring a small memory, thereby executing the main processing at a low sampling rate. The inverted phase is detected by detection of an unnecessary base band delay in synchronizing processing and filter processing to reduce the operation volume. A 225ms delay line used in this case is realized with a small memory by the thinning processing.
Inventors:
Inori Kazunori
Application Number:
JP30021795A
Publication Date:
October 09, 2001
Filing Date:
November 17, 1995
Export Citation:
Assignee:
Matsushita Electric Industrial Co., Ltd
International Classes:
H03H21/00; H04B3/23; (IPC1-7): H04B3/23; H03H21/00
Domestic Patent References:
| JP7193527A | ||||
| JP750857A | ||||
| JP6311073A |
Attorney, Agent or Firm:
Masahiro Kurai