Technical Glossary -- (Kurt Smith)

A5 is the encryption algorithm commonly used by GSM networks in Europe. It has a 64-bit key, although in practice at least ten of these bits are unused. A weaker version of A5 called A5/2 is exported to some countries, including Australia. It was originally a secret algorithm but was eventually leaked, which helped the case for using the open Kasumi algorithm as a replacement for A5. Comp128 is the more common GSM alternative to A5

advanced analogue coding

Abandoned call is one in which a connection is made with the recipient, but the caller then decides to terminate the call before any proper communication is established. Organisations usually wish to keep abandoned calls to a minimum, as they may indicate a slow response to incoming calls

AC Wall Charger is an essential accessory for use with mobile�phones and other electronic devices. The charger enables the mobile device to be powered, and for its battery to be recharged, by connecting it to a mains electricity supply socket. AC wall chargers are often the only means of recharging the battery, and are usually supplied with a phone as they are designed to work with a particular product or type of battery. Wall chargers should not be interchanged without first taking advice, or expensive damage could result. Also note that it is normal for chargers to get warm while in use

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