Title:
DTMF RECEIVER
Document Type and Number:
Japanese Patent JP2500742
Kind Code:
B2
Abstract:
PURPOSE: To provide the DTMF receiver used for an automatic answering telephone set provided with a remote control function and capable of saving power consumption and curtailing the number of operation processing steps.
CONSTITUTION: A DTMF signal received through a telephone line is separated by a group separation filter circuit 1 and a limiter circuit 2 detects a signal level from an output voltage of the group separation filter circuit 1. On the other hand, a register circuit 6 stores selection control information for a frequency to designate a DTMF signal subject to reception processing. Thus, a band pass filter circuit 3 passes through a group unit output of the limiter circuit based on selection control information of the register circuit 6. Furthermore, an output of the band pass filter circuit 3 is rectified by a rectifier circuit 4 and the output of the rectifier circuit 4 is decode-processed by a logic circuit 5 and the reception time is measured.
Inventors:
TANAKA SHIGENOBU
Application Number:
JP8582793A
Publication Date:
May 29, 1996
Filing Date:
April 13, 1993
Export Citation:
Assignee:
NIPPON ELECTRIC CO
International Classes:
H04M11/00; H04Q1/45; (IPC1-7): H04Q1/45; H04M11/00
Attorney, Agent or Firm:
Naoki Kyomoto (2 outside)