Technical Glossary -- (Kurt Smith)

Also known as: AGCH Access Grant Channel (AGCH) is a downlink channel (base to mobile) used by a BS (Base Station) to tell the MS (Mobile Station) which DCCH (Dedicated Control Channel) to use, after the MS has previously requested access to the network by sending a message over the RACH (Random Access Channel). The AGCH is used to assign resources to the user who has requested access to the network, and the BS allocates a TCH (Traffic Channel) or SDCCH (Stand-Alone Dedicated Control Channel) to the MS, allowing it access to the network

Also known as: Algebraic Code Excited Linear Prediction Algebraic Code Excited Linear Prediction, or ACELP, is a speech compression system, used to provide a good standard of speech quality when the network is operating at low data rates (i.e. narrow bandwidth). The analogue voice signal is converted to a digital data signal, so that it can be compressed for transmission over the network, and the process is then reversed at the other end when the digital data is converted back to an analogue voice signal. The quality of the reproduced speech will appear to be much better at the receiving phone than would have been the case if an ACELP system had not been used. The technology associated with ACELP is defined by the ITU-T (International Telecommunications Union-Telecommunication Standardization Sector) and this has been used for a long time as a standard on the Internet for voice applications, being integrated into software such as Microsofts MediaPlayer?.

ActionScript is an ECMAScript-based programming language used for scripting Adobe Flash movies and applications.

Also known as: Thin Film Transistor, TFT TFT (Thin Film Transistor or Active Matrix) LCD is a mass produced display technology that offers improved refresh rates and good contrast over passive matrix displays. It achieves this by adding an individual switch at every single pixel, which means that voltage can be actively supplied to individual pixels instead of one row and one column receiving current at a time. A thin film transistor at each pixel allows much greater contrast and vastly improved refresh rates compared with older displays. This makes full motion video feasible with an active matrix. The two disadvantages to TFT displays are that they have higher power consumption as each individual pixel drains current, and they are more expensive; it is not cheap to manufacture perfect large sheets of transistors, as current processes are low-yield

Also known as: ADPCM Adaptive Differential Pulse Code Modulation (ADPCM) is a compression/decompression technique, used for converting analogue sound or data into a string of digital binary code. Frequent samples are taken of the analogue signal, and the difference between the actual value of each sample and its predicted value (derived from the previous samples) is quantized and converted to a digital signal. This technique is called 'adaptive', because the encoding predictions are adjusted in accordance with the changing characteristics of the input signal, and the coding scale is modified to accommodate any large or small differences. The ADPCM method of encoding takes up less storage space, and produces a lower bit rate, than standard PCM (Pulse Code Modulation). This greater efficiency is achieved because only the differences between samples are recorded. At the decoder the quantized difference signal is added to the predicted signal to produce the reconstructed speech signal. ADPCM can typically give a compression ratio of 4:1, and one version of ADPCM is used to encode audio and compress more data onto Sony's Mini Discs

analogue to digital converter

Also known as: Asymmetric Digital Subscriber Line Asymmetric Digital Subscriber Line (ADSL) is a technology allowing high rates of digital data to be sent over conventional twisted-pair copper telephone lines. It is referred to as asymmetric because it provides a significantly greater bandwidth in one direction than the other, with faster data transfer from the network to the subscriber than it is in the opposite direction. Consequently, ADSL suits the Internet user who downloads large amounts of data from the Net, but tends to send comparatively little data back in return. Theoretically, data speeds of up to 9 Mbps (megabits per second) are possible downstream to the customer, and up to 800 kbps (kilobits per second) upstream. This high-speed, high bandwidth digital communication makes live MPEG2 video signals possible, as well as a range of other multimedia broadband services. However, in practice capacity is lower than the theoretical maximum, because line length reduces data speed and limits the exchange to subscriber distance at about 2 miles. ADSL requires the installation of a special modem, but ADSL then provides an 'always on' connection to subscribers. Simultaneous voice and data transmission is also possible over the same line, because the data transfer uses a section of the phone line bandwidth not utilised by voice. Therefore, subscribers can leave their computers logged onto the Net without interrupting their normal phone connections. A form of ADSL, called Universal ADSL (G.lite), has been approved as a standard by the ITU-TS for services to homes and businesses. Universal ADSL can provide speeds of up to 1.5 Mbps over conventional phone lines. However, although a provider might typically offer a downstream rate of 512 kbps, this is still about 10 times faster than the fastest analogue-to-digital modems, and several times faster than an ISDN (Integrated Services Digital Network) connection. Upstream speeds can reach 128 kbps

Also known as: AMPS Advanced Mobile Phone Service (AMPS) is a first generation analogue cellular telephone system that originated in the USA in the 1980s. AMPS is still the most widely deployed cellular system in the United States, and has been used in other countries of North and South America, as well as the Asia/Pacific region, although it is not compatible with European mobile phone standards. AMPS can be found in countries such as Canada, Australia, Hong Kong, New Zealand, South Korea, Singapore, Taiwan, Thailand and Israel. AMPS operates in the 800 and 900 MHz frequency bands. Frequency Division Multiple Access (FDMA) is used to divide each band of operating frequencies into 30 kHz channels. Adjacent cells will then employ different channels for their transmitted and received signals, so that one cell does not interfere with another, and as a user moves between cells the channels change without any noticeable transition. AMPS was updated with digital cellular service, i.e. digital AMPS (DAMPS), by adding Time Division Multiple Access (TDMA) to each channel

A form of fictional simulation. These are often set in fantasy worlds and involve decision making and exploration.