Title:
DIGITAL POTABLE TELEPHONE SET
Document Type and Number:
Japanese Patent JP2576690
Kind Code:
B2
Abstract:
PURPOSE: To reduce the sense of incompatibility caused by difference between surrounding noise generated by a decoder and the surrounding noise of a source voice by providing a noise control circuit at the portable telephone set and generating a hysteresis characteristic at a threshold level for deciding this signal input/output characteristic corresponding to the increase/decrease of signals.
CONSTITUTION: An analog signal, namely, an up voice signal from a microphone 1 is converted to a digital signal by an A/D converter 2 and this signal is inputted to a noise suppressing circuit 3. The output signal of the circuit 3 is coded by a coder 4, and the coded signal and the control signal of a telephone set control circuit 5 are outputted from a time division multiple access (TDMA) control circuit 6 to a modulator 7 while performing time division multiplex access. At the modulator 7, modulation in a π/4 shift QPSK system is loaded to the time division multiplex accessed signal and the signal is outputted to a power amplifier 8. On the other hand, a radio wave from a reference station is received through an antenna 10 to a receiver 11, the signal from here is demodulated by a demodulator 12 in a delay detecting system, this signal is time-divided and applied to the circuit 5 and a decoder 13, and the decoded voice signal is outputted through a D/A converter 14 to a speaker 15.
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Inventors:
SANO HIDEO
Application Number:
JP5032293A
Publication Date:
January 29, 1997
Filing Date:
March 11, 1993
Export Citation:
Assignee:
NIPPON ELECTRIC CO
International Classes:
G10L19/012; G10L19/038; G10L19/08; H03G3/32; H04B1/10; H04B1/40; H04B7/26; H04B14/04; H04R9/08; H04S1/00; H04W88/02; (IPC1-7): H04B14/04; G10L9/14; G10L9/18; H04B1/10; H04B7/26
Domestic Patent References:
| JP63314943A | ||||
| JP4297143A | ||||
| JP485835U |
Attorney, Agent or Firm:
Yosuke Goto (2 outside)