Digital telephone transmitter/receiver

Details Digital telephone transmitter/receiver Digital telephone transmitter/receiver

1999-12-06

2002-08-27

Pham, Chi (Department: 2631)

Pulse or digital communications

Transceivers

C381S345000

Reexamination Certificate

active

06442194

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to input and/or output part of general information communication equipments, electro acoustic equipments, measuring instruments, and systems handling an analog acoustic signal. In particular, the present invention relates to a digital transmitter/receiver implemented in digital speech communication systems.
2. Description of the Prior Art
Conventionally, speech communication using a digital communication system employed an analog to digital converter to convert from analog speech signal to digital transmission at transmitting side and this is recovered to analog signal by a digital to analog converter to drive loudspeaker or earphone at receiving side.
FIG. 4
is a block diagram depicting a schematic configuration of a conventional digital communication system handing analog signals. On a transmitting side, reference numeral
11
denotes an analog microphone; reference numeral
12
denotes an A/D converter; and reference numeral
13
denotes a digital communication channel. On the receiving side, reference numeral
14
denotes a D/A converter, and reference numeral
15
denotes a loudspeaker or earphone.
In such a conventional communication system, there has been a problem that the system requires plural components such as A/D converter, D/A converter, and multiple power supplies annexed thereto, and disturbances such as noise, crosstalk, interference or wiretap in analog signal occurs.
SUMMARY OF THE INVENTION
An object of the present invention is to provide digital transmitter/receiver capable of eliminating problems said above associated with the foregoing analog signal and directly connecting analog speech and digital communication systems with each other.
To achieve the foregoing object, a digital transmitter/receiver generates acoustic pulses in magnitude corresponding to digit positions of the pulses of a digital signal by means of electro acoustic transducer elements corresponding to respective bits that forms a digital signal employed in a communication channel, and synthesizes the pulses in an acoustic field (cavity). In this manner, an electro acoustic D/A converter is composed. As in a general electronic A/D converter, the foregoing electro acoustic D/A converter is to be as a component of an A/D converter. This electro acoustic A/D converter is composed of a subtractor, a comparator, an integrator, a sampling circuit, a serial/parallel converter, and a device annexed thereto. In this manner, a transmitter/receiver having a function for converting an analog acoustic signal to a digital electric signal is composed.


REFERENCES:
patent: 5680467 (1997-10-01), Hansen
patent: 5721783 (1998-02-01), Anderson
patent: 5917921 (1999-06-01), Sasaki et al.
patent: 5953431 (1999-09-01), Yashima et al.

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