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PVR and digital television glossary

We know digital television and the world of PVRs can be a little confusing to newcomers, so we’ve created a glossary of some of the terms that you’ll find used throughout the site and in the forums. Wherever you see a word highlighted in yellow on this site, you can click on it to see the definition in a pop-up window, or you can simply scroll through the list below to find the information you’re looking for.

If there are any words and phrases that you think are missing, please drop us a line via admin @ toppy.org.uk and we’ll do our best to add them.


(also iLink)

Another name for the Firewire connector found on some computers and pieces of digital video equipment.


A commercial company that transmits a fourteen day Electronic Programme Guide in the UK. The 4TV guide can only be accessed on certain digital terrestrial receivers, and you will not be able to receive it unless you can pick up a digital signal for Channel 5. The guide is transmitted each night, so programme changes made during the day will not show up until the next evening.


Active Format Descriptor. A digital video signal may contain an Active Format Descriptor which includes extra information about the aspect ratio of the program. It allows the broadcaster to specify how the program is best displayed, especially in the case of a widescreen program on 4:3 TVs. See also WSS


Altair is the Windows program supplied by Topfield and used to connect to the Toppy via USB. It provides a Laplink-type interface for transferring files between Toppy and Windows PCs.


Conditional Access. A system by which some broadcasts are restricted, using encryption, so that only people with an appropriate means of decoding them can view them. Most conditional access systems allow both ongoing subscriptions and pay-per-view events.


Conditional Access Module. A CAM is a small piece of electronics, a little larger than a credit card, which contains a card reader and associated electronics. CAMs are used to provide decoding functions to digital TV receivers, and fit into a CI slot, so that instead of building a decoder that only understands one Conditional Access method, users can simply buy an appropriate CAM for the broadcasts that they want to view, and insert their subscription card.

Chase play

The ability of a PVR to let you start watching the beginning of a programme while the rest of it is still being recorded.


Common Interface. A Common Interface slot is found on many pieces of Digital Television equipment - in fact, all digital TVs in Europe are required to have a CI slot. CI slots are mostly used to provide access to encrypted programmes, via a CAM and subscription card, but can also be used for other functions. For example, some integrated digital TVs can have their software upgraded via a module plugged into their CI slots.

Component video

(also YUV)

Component Video is a standard for connecting devices like set top boxes to TVs. It's found on some equipment, but is not that widespread, especially in the UK. It's better quality than Composite video, and slightly better than RGB video, in theory, in practice RGB can sometimes have the edge so if possible try both.

Composite video

Composite video uses a single cable (often with yellow plugs) to carry a video signal, and is sometimes used to link set top boxes and televisions. It's probably more often used to connect a camcorder to the socket on the front of your TV set. If possible, you should use a Component or RGB connection.


Content Reference ID. The CRID is part of the information broadcast for the Freeview Playback system, and consists of a set of IDs. Each programme has a unique CRID, and each series has a CRID too. By recording all the items with a matching series CRID, you record a whole series, and by using the programme CRIDs, you can find a repeat showing of a programme, even if the description in the guide is different.


(also DVB-S)

Digital Satellite. Television signals that are received through a satellite dish. In the UK most people associate DSAT with Sky, though there are many channels (admittedly often in other languages) that can be picked up using a non-Sky DSAT receiver. Digital satellite is also known as DVB-S.


(also DVB-T)

Digital Terrestrial Television. This is the system used to broadcast digital TV that can be picked up using an ordinary TV aerial, though depending on your location, your existing aerial may not be suitable. Also known as DVB-T, many countries around Europe, and Australia, are rolling out DTT systems, though the UK's is one of the oldest. In the UK, many people use the name Freeview to mean DTT, though it's strictly speaking not 100% accurate.

Dual Record

A function provided by many PVRs; the ability to record two programmes simultaneously.


Digital Video Broadcasting. The technology used to broadcast digital TV programmes, via cable (DVB-C), satellite (DVB-S) or terrestrial (DVB-T) systems.


Digital Video Interface. A digital connector found on some flat panel TVs and computer monitors, and on a very few set top boxes. Using DVI can give a slightly better picture than an analogue connection.


Event Information Table. This is the part of the Service Information (SI) carried on the digital television broadcast that carries data for the electronic programme guide. On the Topfield PVRs, it's possible to load data into the unit's EIT memory from an external source, as well as using the broadcast information.


Electronic Programme Guide. Information transmitted that provides information about what programmes are on now and next. In some areas, including the UK, a complete 7 day guide is transmitted, and can be accessed by any receiver that is equipped with suitable software. An alternative EPG is transmitted by a company called 4TV, but this is not used by the Topfield PVRs. With a PVR, an EPG usually makes it possible to view forthcoming programs and select easily the ones that you would like to record, instead of having to manually enter recording times.


A high speed connection used to link pieces of digital video equipment to each other, for example digital camcorders and PCs.


Firmware is the term used to describe the software that's embedded in a piece of equipment, for example the software on your mobile phone, or in a PVR like the Toppy. If firmware is upgradeable, then - as long as the manufacturer makes updates available - you will be able to update your product, adding new features, or fixing bugs.


Freeview is the name used to market free to air terrestrial digital TV in the UK. It's also often used to mean any digital TV received through an aerial in the UK, which causes confusion when people refer to the pay channels made available via TopUpTV. If you want to be really pedantic, some of the UK's free channels are broadcast by companies that aren't members of the consortium that owns the Freeview brand. But it's simpler to call the free channels Freeview than spend hours arguing.

Freeview Playback

Freeview Playback is a branding mark for PVRs, which indicates that they have certain features, which are provided by additional information carried in the digital television broadcasts. Those features include the ability to automatically reschedule recordings when a programme is running late, and to automatically record all the episodes of a series.


Free To Air. A channel that is Free To Air is one that has no encryption or restriction imposed upon it; in other words, as long as you have a compatible receiver, you can watch the channel. Most channels broadcast on the UK digital terrestrial system fall into this category.


Free To View. A Free To View channel doesn't cost anything to view, but it is still encrypted, so you need a viewing card, which may be free, or may attract a small fee for the card itself. FTV broadcasts are used, for example, to ensure that people outside a particular country can't watch programmes that aren't intended for them, since allowing a programme to be seen elsewhere can cause contractual problems. You need a Free To View card to watch some free UK television channels via digital satellite.

G code

Another name for VideoPlus.


(also High Definition)

HD television means TV that uses more lines to make up the picture that SDTV. In the UK at the moment, HD transmissions are available from Sky and Virgin Media; it is not yet clear if there will ever be terrestrial HD. There are two main standards, called 720p and 1080i. Both are widescreen, and the former has 720 lines and 1280 pixels across the screen, while the latter has a resolution of 1920x1080 lines, with half the lines drawn in alternate frames. To display HD pictures, you need an HD Ready display, and to receive them you need an HDTV receiver.

HD Ready

HD Ready is a standard defined by a European group of manufacturers, to indicate whether or not a display is capable of showing high definition content. To qualify, it must have a wide screen, at least 720 lines, and a digital input with HDCP - a form of copy protection. Since it?s a standard for screens, it isn?t something that could be applied to a PVR like the Toppy. See also HDTV


High bandwidth Digital Copy Protection. HDCP is a system that will be used with High Definition video equipment to ensure that people can't make unauthorised copies of material.


High Definition Multimedia Interface. Basically DVI plus sound, hence multimedia. HMDI to DVI can be done with a cable. HDMI is a means of linking digital video equipment together, but is not yet found on much equipment.


The HDTV logo is a mark that will appear on equipment that meets a standard laid down by european equipment makers. It indicates that a product can receive and process high definition signals; you will find it on high definition satellite boxes, for example. When it appears on a TV set, it indicates that the set also meets the HD Ready criteria.


Integrated Digital TV. A television set with a built in digital TV receiver/decoder. With an IDTV, you don't need a separate digibox to watch digital channels.


Integrated Receiver Decoder. A term used in the TF5800 menus, to refer to the digital TV decoding system; it's a hang over from when not all the parts of a system were integrated in one box.


Logical Channel Number. The LCN is the digital channel number that is used to select a channel on your box, for example 1 for BBC1 or 40 for BBC News 24. LCNs are constant, just as you might find almost every analogue TV has BBC1 on the first button, BBC on the second and so on. Don't confuse the LCN with the UHF channel; all the channels on a multiplex will have the same UHF channel, but individual LCNs.


MyStuff Extended Information. MEI files are a popular format for UK Toppy users, and were originally created to use with a PC application generating extended programme information, from internet sources, for the MyStuff TAP. Information can include detailed descriptions of programmes, film ratings, genres and more. The MEI format is used by a range of other TAPs, including some which create MEI files from Freeview broadcast data.


MHEG is a system for creating applications used on the UK digital terrestrial TV system. The text services found on the BBC channels are MHEG applications, as are the Teletext pages, and similar interactive systems. Few other countries use MHEG, preferring MHP instead. The use of MHEG in the UK is largely a legacy of the old OnDigital system.


Multimedia Home Platform. This is the system used in many countries (except the UK, where MHEG is used) to provide interactive facilities on digital TV broadcasts.


Motion Picture Experts Group. A group that sets standards for digital video. MPEG2 is used by most current digital broadcasting systems. MPEG4 is a more efficient standard, that can provide better quality pictures in less space, but is not yet widely used. It will be used for some pay services in France, and for some high definition broadcasts. In almost all cases, it won't be possible to upgrade an existing digital TV receiver based on MPEG2 to cope with MPEG4.


(also H.264)

MPEG4 is the term often used to refer to MPEG4/AVC, or H.264 video coding, which is the standard that will be used in Europe for HD broadcasts; it may also be used for some SD transmissions, since it?s more efficient. Note, however, there are other variants of MPEG4, such as DiVX, and often when media players say they support MPEG4, they mean that, rather than support for MPEG4/AVC.


(also mux)

A multiplex is a group of channels that has been bundled into a stream of digital data and is transmitted on a single UHF channel, which is the space that would be taken up by a single analogue channel. Note that LCNs are not the same as UHF channel numbers.


Network Information Table. A part of the data broadcast that tells digital TV receivers about the channels available, the numbers that they should be allocated to, and the frequencies used by transmitters. In some parts of the UK, the NIT is now split into several parts, which causes problems scanning channels on boxes that do not correctly interpret the information.


The technical standard used for analogue colour TV broadcasts in the USA and some other countries.


One of the first digital terrestrial TV services in the world, OnDigital provided a range of pay channels to customers in the UK, subsequently changing its name to ITV Digital and then going bust. However, as a result, there are still many of the old OnDigital boxes in use in the UK; the boxes are slow and often don't compare well against modern models, but they do feature a card slot for use with the SECA encryption system, so can be used to receive TopUpTV transmissions as well as Freeview.


Over The Air. The term used to describe data that's sent to a device without it needing to be plugged into another computer. OTA updates are used on digital television to send software updates to set top boxes, so that a manufacturer can update all the units that have been sold, as long as they're switched on and connected to an aerial.


The technical standard used for analogue colour TV broadcasts in the UK, most of Europe and other countries.


(also RCA)

A phono conection is a small round socket with a hole for a central pin. Phono connectors are often used for audio, with the usual colour coding of white or black for left channel and red for right channel. Yellow phono connectors are often used for Composite video.


Personal Video Recorder. A unit that records TV programmes onto a hard disk, and usually offers a range of other features, such as the ability to schedule recordings from a on-screen guide, or to automatically record all the episodes of a particular series.


Red Green Blue. An RGB connection sends information from your digital TV decoder or VCR to your television. Usually either an RGB or Component connection via a good quality cable will give you the best picture available from an analogue TV.


A small round connector used to carry video signals. Reasonable quality - better than composite, but not as good as Component or RGB.


Sony/Philips Digital Interface. A digital connection found on some audio and audio-visual equipment that allows you to feed the sound in digital format from one piece of equipment to another. If you have a good quality amplifier, you may find the output from a DVD player or set top box is better when you use its digital audio facilities, instead of a phono connection for the audio. Digital audio connections can also carry multi-channel surround sound.


A SCART connector is a large multipin connector, like a rectangle with a wedge missing from one corner. SCART cables are used in Europe and Australia to link up equipment such as DVD players, TVs, video recorders, and digital TV decorders. Cheap SCART cables may only carry some signals - for example, just composite video - but a full SCART connection can provide RGB video, and also other information, for example to wake up a TV from standby, or for a digital TV decoder to tell a VCR to start recording.


(also SD)

Standard Definition. In Europe and Australia, standard definition analogue TV has 625 lines, of which some are used for things such as teletext. Digital SD has a resolution of 720 pixels across and 576 vertically - equivalent to 576 lines. By comparison, many VHS video recorders have an effective resolution of less than 300 lines, so you'll notice the difference when you switch to a PVR instead of a video recorder.

Season Pass

(also Series Link)

A function on a PVR that allows you to program it to record all the episodes of a particular program. At its simplest, it may be just a regular weekly recording, but a true series link should catch all the episode of a series, no matter what time they're broadcast.


SECA is the form of encryption used by the pay TV service on the UK's digital terrestrial service. You need an appropriate viewing card and either a decoder with a card slot, or a CAM. See TopUpTV.


The colour system used to transmit analogue TV pictures in France.


Setanta is a broadcaster of sports programmes. They operate a channel on terrestrial TV that provides some football, golf and other sports, for a monthly fee.


The name used in some other countries forVideoPlus.


Topfield Application. TAPs are small programs that can be transferred to certain Topfield PVRs, including the TF5800 and TF5810, and provide a range of enhancements. The most common TAPs provide functions such as an enhanced EPG, better management of timers and recordings, or even automatic recording of programmes.

Time Slip

(also TimeShift)

Most often used to refer to the ability of a PVR to record continuously while you're watching, so you can pause to answer the phone, and then catch up by skipping past the adverts.


One of the first PVRs on the market, the Tivo provides a sophisticated EPG, and can even record programmes based on themes, as well as just series.


TopUpTV is a pay service operating on the UK digital terrestrial system; their present service is based around a special PVR which downloads and organises programmes overnight. You can no longer subscribe to their original service, and though the Toppy can record from the new one with a suitable card and CAM, you can?t sign up without paying for their PVR. You can find a link to their site in the General links section of this site.

UHF channel

A UHF channel is a number indicating a part of the radio spectrum used for broadcasting TV. Each analogue channel uses one UHF channel, as does each digital TV multiplex. The same multiplex will use different UHF channels in different parts of the country, to make sure there's no interference. On digital TV, you only need to use the UHF channel number when you manually tune in your receiver to add extra channels. UHF channels used in the UK are presently numbered from 21 to 69.

UHF modulator

A UHF modulator is a device found in some digital TV decoders which will turn the channel that the decoder is tuned into back into an analogue signal, so that it can be fed into a television set that doesn't have a SCART socket.


Universal Serial Bus. A simple connector found on most PCs and on some PVRs, which can be used to connect different devices. Some USB devices are hosts - like PCs - while others, such as hard disks and the Topfield PVRs, are designed to be plugged into a host.


VideoPlus is the system of numeric codes printed in newspapers next to TV listings, which can be entered in to video recorders to make programming easier. Most newspapers don't print codes for multi-channel TV, so the system is of limited use to PVR users.


Wide Screen Signalling. Line 23 of a PAL video signal may contain extra Wide Screen Signalling information which includes the aspect ratio of the program. 16:9 TVs may use this information to display the program in the correct aspect ratio. See also AFD