| Annex A |
OFDM | Orthogonal Frequency Division Multiplex: A modulation technique |
| used for digital TV transmission in Europe, Japan and Australia; |
| more spectrally efficient than FDM. In OFDM, data is distributed |
| over a large number of carriers spaced apart at precise frequencies. |
| The carriers are arranged with overlapping sidebands in such a way |
| that the signals can be received without adjacent channel |
| interference. |
OPPV | Order ahead Pay Per View: An advance purchase of encrypted one- |
| time events with an expiry date. |
OSD | |
| from the SMS, and displayed on the subscriber’s TV screen by the |
| IRD, to inform the subscriber of problems or instruct the subscriber |
| to contact the SMS. |
Packet | A unit of data transmitted over a packet switching network. A packet |
| consists of a header followed by a number of contiguous bytes from |
| an elementary data stream. |
PAL | Phase Alternating Line: A colour TV broadcasting system where the |
| phase of the |
| alternate line to average out errors providing consistent colour |
| reproduction. |
PAT | Program Association Table: Part of the |
| Information (PSI) data and is mandatory for |
| The PAT points (maps) to the PMT. |
PCM | Pulse Code Modulation: A process in which a signal is sampled, |
| each sample is quantized independently of other samples, and the |
| resulting succession of quantized values is encoded into a digital |
| signal. |
PCR | Program Clock Reference: A time stamp in the transport stream |
| from which the Decoder timing is derived. |
PDC | Program Delivery Control: A Teletext service allowing simple |
| programming (i.e. VideoPlus) of VCR recording times. If the desired |
| program is rescheduled, PDC updates the programming information |
| in the VCR. |
Pel | Picture Element: Also known as a pixel. The smallest resolvable |
| rectangular area of an image either on a screen or stored in |
| memory. |
| colour. Monochrome and |
| For |
| creating a range from dark to light (a scale of |
| pixel). Colour systems use a red, green and blue dot per pixel, each |
| of which is energized to different intensities, creating a range of |
| colours perceived as the mixture of these dots. If all three dots are |
| dark, the result is black. If all three dots are bright, the result is |
| white. |
EN/LZT 790 0005 R1A |