Digital Signal 0
Encyclopedia
Digital Signal 0 is a basic digital
signaling rate of 64 kbit/s, corresponding to the capacity of one voice-frequency-equivalent channel
. The DS0 rate, and its equivalents E0
and J0, form the basis for the digital multiplex transmission
hierarchy in telecommunications systems used in North America, Europe, Japan, and the rest of the world, for both the early plesiochronous
systems such as T-carrier
and for modern synchronous systems such as SDH/SONET
.
The DS0 rate was introduced to carry a single digitized voice call. For a typical phone call, the audio sound is digitized at an 8 kHz sample rate using 8-bit pulse-code modulation
for each of the 8000 samples per second. This resulted in a data rate of 64 kbit/s.
Because of its fundamental role in carrying a single phone call, the DS0 rate forms the basis for the digital multiplex transmission
hierarchy in telecommunications systems used in North America. To limit the number of wires required between two involved in exchanging voice calls, a system was built in which multiple DS0s are multiplexed together on higher capacity circuits. In this system, twenty-four (24) DS0s are multiplexed into a DS1
signal. Twenty-eight (28) DS1s are multiplexed into a DS3
. When carried over copper wire, this is the well-known T-carrier
system, with T1
and T3
corresponding to DS1 and DS3, respectively.
Besides its use for voice communications, the DS0 rate may support twenty 2.4 kbit/s channels, ten 4.8 kbit/s channels, five 9.67 kbit/s channels, one 56 kbit/s channel, or one 64 kbit/s clear channel.
E0
(standardized as ITU G.703
) is the European equivalent of the North American DS0 for carrying . However, there are some subtle differences in implementation. Voice signals are encoded for carriage over E0 according to ITU G.711
. Note that when a T-carrier
system is used as in North America, robbed bit signaling
can mean that a DS0 channel carried over that system is not an error-free bit-stream. The out-of-band signaling used in the European E-carrier
system avoids this.
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
signaling rate of 64 kbit/s, corresponding to the capacity of one voice-frequency-equivalent channel
Channel (communications)
In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...
. The DS0 rate, and its equivalents E0
E-carrier
In digital telecommunications, where a single physical wire pair can be used to carry many simultaneous voice conversations by time-division multiplexing, worldwide standards have been created and deployed...
and J0, form the basis for the digital multiplex transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
hierarchy in telecommunications systems used in North America, Europe, Japan, and the rest of the world, for both the early plesiochronous
Plesiochronous
The term Plesiochronous is derived from the Greek plesio, meaning near, and chronos, time, and refers to the fact that plesiochronous systems run in a state where different parts of the system are almost, but not quite perfectly, synchronised....
systems such as T-carrier
T-carrier
In telecommunications, T-carrier, sometimes abbreviated as T-CXR, is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America, Japan, and South Korea....
and for modern synchronous systems such as SDH/SONET
Sonet
Sonet may refer to:* Sonet Records, European record label* Synchronous optical networking * Saab Sonett...
.
The DS0 rate was introduced to carry a single digitized voice call. For a typical phone call, the audio sound is digitized at an 8 kHz sample rate using 8-bit pulse-code modulation
Pulse-code modulation
Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the standard form for digital audio in computers and various Blu-ray, Compact Disc and DVD formats, as well as other uses such as digital telephone systems...
for each of the 8000 samples per second. This resulted in a data rate of 64 kbit/s.
Because of its fundamental role in carrying a single phone call, the DS0 rate forms the basis for the digital multiplex transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
hierarchy in telecommunications systems used in North America. To limit the number of wires required between two involved in exchanging voice calls, a system was built in which multiple DS0s are multiplexed together on higher capacity circuits. In this system, twenty-four (24) DS0s are multiplexed into a DS1
Digital Signal 1
Digital signal 1 is a T-carrier signaling scheme devised by Bell Labs. DS1 is a widely used standard in telecommunications in North America and Japan to transmit voice and data between devices. E1 is used in place of T1 outside North America, Japan, and South Korea...
signal. Twenty-eight (28) DS1s are multiplexed into a DS3
Digital Signal 3
A Digital Signal 3 is a digital signal level 3 T-carrier. It may also be referred to as a T3 line.*The data rate for this type of signal is 44.736 Mbit/s.*This level of carrier can transport 28 DS1 level signals within its payload....
. When carried over copper wire, this is the well-known T-carrier
T-carrier
In telecommunications, T-carrier, sometimes abbreviated as T-CXR, is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America, Japan, and South Korea....
system, with T1
Digital Signal 1
Digital signal 1 is a T-carrier signaling scheme devised by Bell Labs. DS1 is a widely used standard in telecommunications in North America and Japan to transmit voice and data between devices. E1 is used in place of T1 outside North America, Japan, and South Korea...
and T3
Digital Signal 3
A Digital Signal 3 is a digital signal level 3 T-carrier. It may also be referred to as a T3 line.*The data rate for this type of signal is 44.736 Mbit/s.*This level of carrier can transport 28 DS1 level signals within its payload....
corresponding to DS1 and DS3, respectively.
Besides its use for voice communications, the DS0 rate may support twenty 2.4 kbit/s channels, ten 4.8 kbit/s channels, five 9.67 kbit/s channels, one 56 kbit/s channel, or one 64 kbit/s clear channel.
E0
E-carrier
In digital telecommunications, where a single physical wire pair can be used to carry many simultaneous voice conversations by time-division multiplexing, worldwide standards have been created and deployed...
(standardized as ITU G.703
G.703
G.703 is an ITU-T standard for transmitting voice or data over digital carriers such as T1 and E1. G.703 provides specifications for pulse code modulation .G.703 also specifies E0...
) is the European equivalent of the North American DS0 for carrying . However, there are some subtle differences in implementation. Voice signals are encoded for carriage over E0 according to ITU G.711
G.711
G.711 is an ITU-T standard for audio companding. It is primarily used in telephony. The standard was released for usage in 1972. Its formal name is Pulse code modulation of voice frequencies. It is required standard in many technologies, for example in H.320 and H.323 specifications. It can also...
. Note that when a T-carrier
T-carrier
In telecommunications, T-carrier, sometimes abbreviated as T-CXR, is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America, Japan, and South Korea....
system is used as in North America, robbed bit signaling
Robbed bit signaling
In communication systems robbed-bit signaling is a scheme to provide maintenance and line signaling services on many T1 digital carrier circuits using Channel Associated Signaling ....
can mean that a DS0 channel carried over that system is not an error-free bit-stream. The out-of-band signaling used in the European E-carrier
E-carrier
In digital telecommunications, where a single physical wire pair can be used to carry many simultaneous voice conversations by time-division multiplexing, worldwide standards have been created and deployed...
system avoids this.