Glossary
Instruction Manual: evolution 5000 E57xx DSNG and DENG Voyager Encoder Page A-5
ST.TM.E10076.3
IF Intermediate Frequency: Usually refers to the 70 MHz or 140 MHz output of th e Modulator in cable, satellite and
terrestrial transmission applications.
Interframe Coding Compression coding involving consecutiv e frames. When consecutive frames are compared, temporal redundancy
is used to remove common elements (information) and arrive at difference information. MPEG-2 uses B and P
frames, but since they are individually incomplete and relate to other adjacent frames, they cann ot be edited
independently.
Intraframe Coding Compression coding involving a single frame. Re dundant information is removed on a per frame basis. All other
frames are ignored. Coding of a macroblock or picture that uses information only from that m acroblock or picture.
Exploits spatial redundancy by using DCT to produce I frames; these are independent frames and c an be edited.
IP Internet Protocol: The IP part of TCP/IP. IP implements the network layer (layer 3) of the protocol, which contains
a network address and is used to route a message to a different network or sub-network. IP accepts packets from
the layer 4 transport protocol (TCP or UDP), adds its own header to it and deliv ers a datagram to the layer 2 data
link protocol. It may also break the packet into fragments to support the Maximum Transmissi on / Transfer Unit
(MTU) of the network.
I-picture; I-frame Intracoded Picture/Frame: A picture / frame, which is c oded using purely intracoding with reference to no other
field or frame information. The I frame is used as a reference for other compressi on methods.
IPPV Impulse Pay Per View: One-time events, purchased at home (on impulse) using a prearranged SMS credi t line.
IRD Integrated Receiver Decoder: The Receiver with an internal MPEG Decoder, which is c onnected to the
subscriber’s TV. The IRD is responsible for receiving and de-multiplexing al l signals. The unit receives the
incoming signal and if CA is active, decodes the signal when provided with a control word by the viewing card.
Domestic IRDs are also known as Set-Top Units or Set-Top Boxes.
IRE Institute of Radio Engineers: No longer in existence but the name lives on as a unit of video amplitude
measurement. This unit is 1% of the range between blanking a peak white for a standard ampli tude signal.
ISDN Integrated Services Digital Network: The basic ISDN service is BRI (Basic Rate Interface), which is made up of
two 64 kbit/s B channels and one 16 kbit/s D channel (2B+D). If both channels are combined into one, cal led
bonding, the total data rate becomes 128 kbit/s and is four and a half times the bandwidth of a V.34 modem
(28.8 kbit/s).
The ISDN high-speed service is PRI (Primary Rate Interface). It provides 23 B channels and one 64 kbit/s D
channel (23B+D), which is equivalent to the 24 channels of a T1 line. When several channels ar e bonded together,
high data rates can be achieved. For example, it is common to bond six channels for quality videoconferencing at
384 kbit/s. In Europe, PRI includes 30 B channels and one D channel, equivalent to an E1 line.
ISO International Standards Organisation.
ISOG Inter-union Satellite Operations Group.
ITS Insertion Test Signal: A suite of analogue test signals placed on lines in the VBI. Also known as VITS.
ITT Invitation To Tender.
ITU-R International Telecommunications Union - Radiocommunications Study Groups (was CCIR).
ITU-T International Telecommunications Union - Telecommunications Standardisation Sector (was CCITT).
JPEG Joint Photographic Experts Group: ISO/ITU standard for compressing still images. It has a high compression
capability. Using discrete cosine transform, it provides user specified compression ratios up to around 100:1 (there
is a trade-off between image quality and file size).
kbit/s 1000 bits per second.
Kbit 1024 bits, usually refers to memory capacity or allocation.
Ku-band The portion of the electromagnetic spectrum, which spans the frequency rang e of approximately 12 GHz to
14 GHz. Used by communications satellites. Preferred for DTH applications because this range of frequency is
less susceptible to interference.
LAN Local Area Network: A network, which provides facilities for communications within a defined building or group of
buildings in close proximity.
L-band The frequency band from 950 MHz to 2150 MHz, which is the normal input-frequency-range of a dom estic IRD.
The incoming signal from the satellite is down-converted to L-band by the LNB.
LED Light Emitting Diode.
LNB Low No ise Block Down-Converter: The component of a subscriber satellite transmission receiving dish which
amplifies the incoming signal and down-converts it to a suitable frequency to input to the I RD (typically 950 MHz -
1600 MHz).
LO Local Oscillator.
LSB Least significant bit.
Luminance The television signal representing brightness, or the amount of light at any point in a picture. The Y in YCRCB.