Analogue
Picture or audio signals are converted into electromagnetic oscillations and then broadcast using frequencies (or via cables).
API
Application Programming Interface: application program interface which permits communication between a broadcasting application program and the set-top box operating system.
Artefact
Picture or audio interference caused by digital signal broadcasting. Artefacts occur especially if there are rapid movements at the edges when the picture is stored or transmitted with high data compression.
Audio stream
Audio streams are continuous digital radio data streams with MPEG 1 Layer 2 framing format for representing acoustic information. They enable normal radio programmes to be transmitted and heard on a receiver. MUSICAM is the format used in digital radio, with two MPEG-compliant PADs for additional data: F-PAD and X-PAD - also known as PAD data services. These are generally used for transmitting program associated data, i.e. data which is directly associated with the acoustic information. However, in digital radio data can also be transmitted outside the audio stream, in separate NPAD subchannels which can also be transmitted in packet mode.
Bandwidth
With bandwidth, a distinction must be made between capacity and frequency band. The width of an occupied frequency band is given in Hz (Hertz) and describes a range of the electromagnetic frequency spectrum. For example, a range of 228.304 MHz to 229.840 MHz has a bandwidth of 1.536 MHz. The capacity, however, is given in bit/s. For example, 1.7 Mbit/s data rate (or bandwidth) for a DAB ensemble. However, the two uses of the term are closely interrelated because more space in the frequency band also permits greater transmission capacities.
Bit
Smallest unit in digital signals; each bit represents a decision element (0 or 1).
Bouquet
Describes a programme package which can be received in DVB-T consisting of 4 to 10 television programmes and additional services. A bouquet can be released for each available frequency block (see also Ensemble).
COFDM
Acronym for Coded Orthogonal Frequency Division Multiplex. Method of transmitting DAB data; the information is divided into a large number of subchannels in a wide frequency block. This ensures high interference protection.
Conditional Access (CA)
Digital access and billing system used for marketing radio and television programmes. CA comprises individual services related to technologies (encoding, smart cards, decoding) and customers (billing, customer management). CA systems can be offered individually or as a package by broadcasters, cable network operators and even by independent companies.
