A Digital Signal 3 (DS3) is a digital signal level 3
T-carrier
The T-carrier is a member of the series of carrier systems developed by AT&T Bell Laboratories for digital transmission of multiplexed telephone calls.
The first version, the Transmission System 1 (T1), was introduced in 1962 in the Bell Syste ...
. It may also be referred to as a T3 line.
*The data rate for this type of signal is 44.736 Mbit/s (45 Mb).
*DS3 uses 75ohm coaxial cable and BNC connectors.
*This level of carrier can transport 28
DS1 level signals within its payload.
*This level of carrier can transport 672
DS0 level channels within its payload.
*Such circuits are the usual kind between
telephony carriers, both wired and
wireless
Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most ...
, and typically by
OC1 optical connections.
Cabling
DS3 interconnect cables must be made with true 75-ohm
coaxial cable and connectors. Cables or connectors which are 50 ohms or which significantly deviate from 75 ohms will result in
signal reflection
In telecommunications, signal reflection occurs when a signal is transmitted along a transmission medium, such as a copper cable or an optical fiber. Some of the signal power may be reflected back to its origin rather than being carried all the ...
s which will lower the performance of the connection, possibly to the point of not working.
GR-139-CORE ''Generic Requirements for Central Office Coaxial Cable'', defines type 734 and 735 cables for this application. Due to losses, there are differing distance limitations for each type of cable. Type 734 has a larger center conductor and insulator for lower losses for a given distance. The
BNC connector
The BNC connector (initialism of "Bayonet Neill–Concelman") is a miniature quick connect/disconnect radio frequency connector used for coaxial cable. It is designed to maintain the same characteristic impedance of the cable, with 50 ohm and 7 ...
s are also very important as are the crimping and cable stripping tools used to install them. Trompeter, Cannon, Amphenol, Kings, and Canare make some of the most reliable 75 ohm connectors known.
RG-6
RG-6/U is a common type of coaxial cable used in a wide variety of residential and commercial applications. An RG-6/U coaxial cable has a characteristic impedance of 75 ohms. The term, ''RG-6'', is generic and is applied to a wide variety of ...
or even inexpensive
RG-59
RG-59/U is a specific type of coaxial cable, often used for low-power video and RF signal connections. The cable has a characteristic impedance of 75 ohms, and a capacitance of around 20pF/ft (60pF/m). The 75 ohm impedance matches a dipol ...
cable may work temporarily when properly terminated, though it does not meet telephony technical standards. Type 735 26 AWG is used for interconnects up to 225 feet, and Type 734 20 AWG is used for interconnects up to 450 feet.
DS3 pricing
DS3 service is provided to businesses in the United States through
incumbent local exchange carrier and
competitive local exchange carrier communication providers. The price, much like a T1 (or DS1) line, has two primary components: the
loop (which is distance-sensitive) and the port (or the price the carrier charges to access the internet through their proprietary network).
See also
*
Central Office Multiplexing
*
Digital Signal 0
Digital Signal 0 (DS0) is a basic digital signaling rate of 64 kilobits per second (kbit/s), corresponding to the capacity of one analog voice-frequency-equivalent communication channel. The DS0 rate, and its equivalents E0 in the E-carrier system ...
*
Digital Signal 1
*
DS4/NA
*
Transmux
References
External links
Detailed/Technical DS3-T3 DefinitionThe Fundamentals of DS3, Technical Note, Acterna, TB-FUNDS3-B-2/01
Telecommunications standards
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