Computer-based conversion of digital signals

Details Computer-based conversion of digital signals Computer-based conversion of digital signals

2000-04-20

2004-08-10

Coulter, Kenneth R. (Department: 2154)

Multiplex communications

Communication techniques for information carried in plural...

Adaptive

C375S222000

Reexamination Certificate

active

06775297

ABSTRACT:

TECHNICAL FIELD
This invention relates generally to telecommunication systems, and more specifically to systems that convert communication signals for transmission between interconnected computers.
BACKGROUND ART
Traditionally, data transmission between two interconnected computers was accomplished through the use of analog telecommunication lines. Data communication over analog telecommunication lines could be accomplished by converting digital data into analog signals prior to transmission and converting the analog signals back into digital data upon receipt of the transmission.
The digital/analog conversion function is typically accomplished through a modulator/demodulator (MODEM). Thus, installing a first MODEM between the sending computer and the analog telecommunication line and a second MODEM between the analog telecommunication line and the receiving computer allows digital data to be transmitted using analog signals.
Recent advances in telecommunication technology have made it possible for telecommunication service providers to offer transmission lines which can facilitate the transmission of digital data. Digital data transmissions can be faster, more reliable and error-free than analog transmissions.
There are a number of types of digital telecommunication lines presently offered by telecommunication service providers. One type of telecommunication line that supports the transmission of digital data is commonly referred to in the industry as an integrated services digital network (ISDN) line.
In order to take advantage of an available digital telecommunication line, a computer must be adapted to provide a connection between the computer and the digital telecommunication line. Typically, this connectivity is achieved through the use of a personal computer terminal adapter (PCTA) which allows digital data to be input to and output from the computer.
In order to integrate the digital telecommunication lines into the existing system of analog transmission lines, telecommunication service providers implemented switching stations. These switching stations route transmissions to the appropriate lines and perform a translating function for transmission between analog and digital lines.
The translating function is performed using a Coder/Decoder (CODEC). To translate analog signals into digital data, for example, a CODEC receives analog signals transmitted along an analog telecommunication line, creates a coded digital representation of the analog signals, and transmits the coded digital representation of the analog signals along a digital telecommunication line.
There are several standard encoding schemes presently utilized to translate analog signals representing digital data into encoded digital data describing the analog signals representing digital data. The Mu law, ADPCM and the A law are examples of conversions methods well known in the art which are capable of performing such a translation.
Conversely, when data is being transmitted along a digital telecommunication line to be received using an analog telecommunication line, the switching station via the CODEC performs the reverse translation, namely converting coded digital data into analog signals.
Although switching stations facilitate the transmission of data between analog and digital telecommunication lines, the format of the coded digital data created by a CODEC is not compatible with standard computers. Consequently, a computer directly connected to a digital telecommunication line could not utilize the coded digital data without additional hardware.
Presently, a computer receiving coded digital data from a digital telecommunication line requires a second CODEC to decode the coded digital data to create an analog signal for transmission to a MODEM.
FIG. 1
illustrates the equipment currently necessary for data transmission between a standard personal computer and a public switched network using an analog telecommunication line. The digital data transmitted by the personal computer
100
via the data port
108
will hereinafter be referred to as application data.
In
FIG. 1
, a personal computer
100
, having a keyboard
102
, a monitor
104
, a data port
108
and a program
106
capable of communicating with the data port
108
is attached to a MODEM
110
. The MODEM
110
is connected to an analog telecommunication line
112
which is connected to a public switched network
114
. The public switched network
114
has an attached CODEC
116
which can connect the analog telecommunication line
112
to a digital telecommunication line
118
.
Application data to be transmitted from the personal computer
100
through the public switched network
114
is first passed from the program
106
through the data port
108
to the MODEM
110
. The MODEM converts the digital data into analog signals capable of being transmitted along the analog telecommunication line
112
.
The analog signals are routed by the public switched network
114
to the CODEC
116
which creates coded digital data representing the analog signals. The CODEC
116
transmits the coded digital data representing the analog signals out of the public switched network
114
along the digital telecommunication line
118
.
Although the data transmission described above originates at the personal computer
100
and terminates after the coded digital data passes through the digital telecommunication line
118
, data transmissions in the reverse direction are similarly accommodated. Regardless of the direction of the data transmission, the digital telecommunication line
118
carries coded digital data representing analog signals and the analog telecommunication line
112
carries analog signals.
FIG. 2
illustrates the equipment currently necessary for data transmission between a personal computer having an attached MODEM and CODEC and a public switched network using a digital telecommunication line.
In
FIG. 2
, a personal computer
200
, having a keyboard
202
, a monitor
204
, a data port
208
and a program
206
capable of communicating with the data port
208
is attached to a MODEM
210
. The MODEM
210
is connected to a terminal adapter (TA)
212
. The TA
212
has an attached CODEC
214
. The TA
212
is connected to a digital telecommunication line
216
which is connected to a public switched network
218
.
Application data to be transmitted from the personal computer
200
through the public switched network
218
is first passed from the program
206
through the data port
208
to the MODEM
210
. The MODEM converts the digital application data into analog signals capable of being transmitted along an analog telecommunication line.
The analog signals are transmitted from the MODEM
210
to the CODEC
214
attached to the TA
212
. The CODEC converts the analog signals into coded digital data representing the analog signals. The coded digital data is transmitted from the TA
212
along the digital telecommunication line
216
to the public switched network
218
.
After the public switched network
218
receives the coded digital data representing analog signals, the data can be transmitted out of the public switched network
218
using either a second digital telecommunication line or an analog telecommunication line with an attached CODEC as illustrated in FIG.
1
.
Although the data transmission described above originates at the personal computer
200
and terminates after the coded digital data passes through the public switched network
218
, data transmissions in the reverse direction are similarly accommodated. Regardless of the direction of the data transmission, the digital telecommunication line
216
carries coded digital data representing analog signals.
FIG. 3
illustrates the equipment currently necessary for data transmission between a personal computer having a TA with a rate adapter (RA) and a public switched network using a digital telecommunication line.
In
FIG. 3
, a personal computer
300
, having a keyboard
302
, a monitor
304
, a TA
306
with an attached RA
308
and a program
310
capable of communicating with

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