Title:
HAND-FREE TYPE PORTABLE TELEPHONE TERMINAL EQUIPMENT
Document Type and Number:
Japanese Patent JP3228218
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide a portable telephone terminal equipment capable of giving optimum echo return loss E.R.L. to an echo cancellation circuit even when a vehicle or a mount position differs.
SOLUTION: In the case of attaching this terminal equipment 20 to a vehicle, the terminal equipment is initialized. An initial setting state signal is given to an initial setting signal input 24 of a microcomputer 25. Upon the receipt of the signal, the microcomputer 25 replaces an output of a speaker amplifier 26 with an output of a reference voice generating source 22. The output is picked up by a microphone 4, a microphone input is rectified by a full wave rectifier circuit 23 and the rectified signal is applied to an A/D input of the microcomputer 25. The microcomputer 25 variably controls a gain of a microphone input adjustment section 27 in response to an output level of the full wave rectifier circuit 23 to set the optimum E.R.L. value to an echo cancellation circuit 21a.
Inventors:
Hiroshi Yanagisawa
Application Number:
JP8428798A
Publication Date:
November 12, 2001
Filing Date:
March 30, 1998
Export Citation:
Assignee:
NEC
International Classes:
H04M1/00; H04M1/725; H04M1/60; (IPC1-7): H04M1/60; H04M1/725
Domestic Patent References:
| JP613536A | ||||
| JP6424658A | ||||
| JP2224559A | ||||
| JP9116468A |
Attorney, Agent or Firm:
Nobuo Takahashi (3 outside)