S-Video Output - A dedicated S-video mini-DIN output connects to your TV or VCR for superior picture.

Safe Area - A reduced area of the picture which should contain important action and graphics may be placed without fear of cutoff. With mixed 4x3 and 16x9 viewing, what is safe is a debatable point!

SCART - Syndicat Francais des Constructeurs d'Appareils Radio et Television. A connector with 21 pins found on the back of most televisions, STBs, DVDs and video cassette recorders (VCRs).

SCPC - Single Channel Per Carrier. Some channels have their own carrier frequency and thus are independent from all other signals.

Scrambling - The process of making a signal unintelligible such that it can only be received if an authorised descrambling system is available in the receiver.

SDMI - Secure Digital Music Initiative. A consortium of companies working on copy management aimed at stopping the illegal copying of MP3 files over the internet. Chief Executive is Leonardo Chiariglione, the redoubtable Head of TV Technologies at CSELT, Telecom Italia's research centre. SDMI recently ran a "hack SDMI" challenge to see if four alternative approaches being studied were secure. A team from Princeton University claims to have hacked all four in a couple of man-weeks of effort, thus proving that you will never stop the determined burglar. However, breaking encrypted files this way is clearly illegal and, together with watermarking to identify the source, makes prosecution easier. Meanwhile two code-breakers received cheques for $10,000 for their efforts in pinpointing weaknesses in the schemes.

SDN - S4C Digital Networks, the multiplex operator for mux A which carries Five, S4C and some shopping channels.

SDT - Service Description Table. One of the four mandatory SI tables which lists the names and parameters of each service referred to

Service ID - A unique identifier of a service within a transport stream and part of the SDT.

SFN - Single Frequancy Network. A way of broadcasting from a grid of transmitters using only one frequency. Restrictions on transmitter spacing make it inappropriate for the UK.

Shoot and Protect - The buzz-word which describes framing pictures for display at more than one aspect ratio. Hollywood has been doing it for years, producing 4x3 tv versions from CinemaScope masters; protecting 4x3 viewers from 16x9 originals has to be a darn sight easier!

SI - Service Information

Signing - There are 70,000 deaf people in the UK who use sign language. The Broadcasting Act 1996 requires the signing of 1% of all programmes (15 mins per day) within 1 year of launch. This must increase to 5% within 10 years. Signing is defined in British Sign Language (BSL) but there are variations which can cause confusion.

Simulcrypt - The DVB has given its backing to two approaches to CA, simulcrypt and multicrypt. Simulcrypt is intended to permit different CA operators in different geographic areas. The service carries entitlement messages for each CA provider within an agreed common framework, but the viewer does not have a choice of SMS. In technical simulcrypt, the system is designed to allow two competing CA systems within an agreed framework. Multicrypt is an open system which makes use of the common interface to allow competing CA systems, subject only that the service provider must transmit entitlement messages for each CA provider.

Skew - Fine-tuning of the polarity, which accounts for the different angles of signals from various satellites.

Smart Card - A card used to descramble encrypted broadcasts when placed in a decoder or receiver with a built-in decoder.

SMATV - Satellite Master Antenna Television) Satellite TV distribution system for blocks of flats with single antenna.

SMC - SMS - Subscriber Management Centre - SMS Subscriber Management System. The business centre which issues the smart cards, sends out the bills and receives payment from subscribers. An important resource of the SMS is the database of information about subscribers, the serial numbers of their receivers and information about their preferences and servics to which they have subscribed.

Stat MUX - A more advanced type of multiplexing where if the first channel is fast moving and the other 3 are slow moving, the first channel is allocated more timeslots than the other 3 channels.

STB - Set-top box.

Subsidised Digibox - Eligible ASAs/ASHAs can buy this at a discounted price.