T-1 Essay, Research Paper

T-1’s

T-1s are the backbone of digital service today. A T-1 is a standards-based transmission format. It processes voice or data digital signals over telephone facilities. Many businesses may use a T-1 to connect their PBX system to the public switched network to bridging, or routing between LAN networks, or as transmission devices between microwave stations. T-1s are popular for several reasons. One being that a T-1’s circuit size. It can make 24 communication channels on one circuit. A second reason being that smaller trunk groups can be configured on a single T-1.

Basic T-1 technology is converting analog waves to digital and back to analog. A voice that is being spoken creates an analog sound wave and the telephone creates an electrical representation of the analog waves. When the pitch or frequency would change, the electrical current would change accordingly. A conversion or coding is necessary to convert the analog sound waves to digital. In order to convert analog waves to digital, samples are extracted from the analog waves. The samples of analog waves are taken about 8,000 times every second, which is coded into a 8-bit word (also known as a byte). This procedure is executed by pulse code modulator (PCM) and codec which is a circuit chip. The PCM and codec do the actual conversion from analog to digital and back to analog again.

T-1 lines are improving as time passes on. A T-1 system can be produced from analog voice circuits. 24 analog voice circuits would need to be converted into a digital signal. The digital signal would then need to be multiplexed onto a single four-wire T-1 or span. The addition of paired wires to support the transmission is called pair gain and the reduction of paired wires is called pair reduction. One pair is used for receiving voice or data, on the other hand the other pair is used for the transmission of voice or data. In some cases where a distance is greater than a mile, a repeater is placed every mile to maintain the signal that is being received or transmitted. A new type of T-1, pair-gain repeaterless, utilizes a new kind of repeater which can send the T-1 signal up to 5 miles.

T-1s need clarity due to the high-speed data transmissions. Lost information is very crucial and cannot be tolerated in a T-1. Bridge taps (parallel connecting nodes between end points of a copper wire circuit) hinder the changing of analog installations to support digital T-1. Echo is once again another factor to watch/listen for. A way to help suppress echo is to install an echo suppressor, but there will always be some kind of loss of quality in a telephone call. Another problem for a T-1 can be caused by the use of load coils. Load coils are to boost voltage and quality of analog signals. It is okay for load coils to be used over copper wire and analog signaling but once a T-1 is carried over the copper lines, great data errors will occur if the load coils are not removed. Other factors to watch out for may include water seepage, signal crossover, and normal noises from copper lines. The majority of the factors may be eliminated if the T-1 is originally installed but that does not guarantee that they may arise in the future.

T-1 networking lets customers use many features such as: compressed voice transfer, teleconferencing, enhanced data services, compressed video, automatic selected priority links, best-case routing in case of link failure, end-to-end diagnostics, circuit redundancy with automatic link restoration and increased mean time between failures, aggregate trunk rates, passthrough, DS1 framing, distributed communications systems (DCS), and dynamic bandwidth allocation. There are other features that are not listed due to the fact that features are being developed on a regular basis. Direct Access and Cross-Connect Systems (DACS) deployed digital cross connects because users wanted faster, easier operations, eliminate costs manual special services, and more control over their networks.

There is a wide variety of equipment that is compatible with a T-1 that will provide many functions or services. Popular pieces of equipment that connected to T-1 facilities are: multiplexors, PBXs, central office switching system, toll and tandem switching systems, channel backs, transcoders, echo cancelers, channel service unit, DACS, host computers, bridges, routers, gateways, repeaters, and signal transfer points.

T-1s are vital to world of telephony. They eliminate the middle ground for many different telephone applications. T-1s are very versatile, they may carry analog signals, utilized for voice or data, can be configured for ISDN service, and can also carry video signals. A T-1 is excellent for providing wide band telephony which may make it obsolete in the future.