Transcript
BROADCAST RECEPTION & TELECOMS GUIDE ANALOGUE - DIGITAL - TELEVISION - RADIO SATELLITE - CABLE - SIGNAL AMPLIFICATION & DISTRIBUTION - AUDIO/VIDEO
INDEX The first section of this Broadcast, Reception and Telecom Guide has been written to help you understand the basics of Terrestrial Television, Radio, Satellite and Cable Broadcasting considering both analogue and digital formats. The second section considers reception issues in more detail looking at the different products available in the market and guidelines to successful installation of DIY projects. The third section looks at Telecoms including telephone, fax and modem. This is a very fast moving industry and information will quickly become out of date and be superseded. If you would like any further information please do not hesitate to contact Maxview on the following: Customer Helpline (01553) 811000 website www.maxview.ltd.uk e-mail
[email protected]
TERRESTRIAL TELEVISION BROADCASTING Analogue Terrestrial Broadcasting Digital Terrestrial Broadcasting
3-5 5-6
SATELLITE & CABLE TELEVISION BROADCASTING Analogue Satellite Broadcasting Digital Satellite Broadcasting Digital Cable Broadcasting
7-8 8 8
RADIO BROADCASTING AM Radio Broadcasting FM Radio Broadcasting Digital Audio Broadcasting Satellite Radio Broadcasting Internet Radio Broadcasting
9 9-10 10 10 10
TERRESTRIAL TV AERIALS Types of UHF TV Aerial External/Loft Aerials Indoor Aerials Built-in Loop Aerials
11 11-13 14 14
TERRESTRIAL TV AERIAL INSTALLATION TV Aerial Position TV Aerial Orientation TV Aerial Alignment TV Aerial Downlead TV Aerial Connections
15 16 16 16 16
SATELLITE ANTENNA Types of Satellite Antenna System Domestic Satellite Antenna Touring Satellite Antenna
17 17 17
SATELLITE INSTALLATION 17 Coverage 17-18 Dish Size, Surface Area and Reception Angle Dish Alignment and Adjustment 18 18 LNB and Satellite Receiver RADIO AERIALS Types of FM Aerial External Aerials Indoor Aerials Built-in Aerials DAB Aerials
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19 19 20 20 20
SIGNAL BOOSTERS & MASTHEAD AMPLIFIERS Signal Amplification Signal Distribution Types of Signal Booster Fixed Gain Signal Boosters Variable Gain Signal Boosters
21-22 22 22 22 22
ACCESSORIES TV, Radio and Satellite 23 Accessories Coaxial Cable and 23 RF Connectors Fitting a Coaxial Connector 24 Combining and Splitting 24-25 TV and FM Signals Fitting a F Connector 25 Types of Outlet Socket 26 Flush Mounted Outlet Plates 26 Surface Mounted Outlet Plates 26 Audio/Video Accessories Audio/Video Connections Scart Connector Phono Connector Scart to Phono Connector Universal Remote Controls Cleaning Kits Headphones
27 27 27 27 27 28 28 28
RECEPTION PROBLEMS Analogue Terrestrial TV Snowy Picture Herringbone Pattern Ghosting Co-channel Interference Electrical Interference Digital Terrestrial TV Analogue Satellite TV Sparklies Co-channel Interference Digital Satellite TV Intermittent Connections
29 29 29 29 29 29 29 29 29 29 29 29
TELECOMS & ACCESSORIES Telephone Fax Machines Internet, Modem and Interactive Services Telecom Accessories USEFUL ADDRESSES
30 30 30 30-31 32
TERRESTRIAL TELEVISION BROADCASTING
Analogue Terrestrial Broadcasting Terrestrial television signals were first broadcast in the UK in an analogue format from Crystal Palace in 1955. Analogue terrestrial UHF television stations are broadcast from a network of approximately 1,000 different transmitters around the country. Around 50 of the total transmitter network are high power main transmitters. These are situated on the highest point possible in a region, the largest of which has a power output of approximately 1,000,000 watts.
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The remainder of the transmitter network is made up of relay transmitters, smaller lower power transmitters which receive signals from main transmitters and relay them to homes in areas that are unable to receive signals from the main transmitter. Due to the careful planning of the transmitter network approximately 99.3% of the UK population are able to receive terrestrial analogue channels (85% for channel 5).
In order to avoid interference, neighbouring main transmitters broadcast their signals on a different part of the UHF frequency spectrum. Analogue terrestrial signals are broadcast as an electrical wave and frequencies are allocated to individual broadcasters with a single channel needed for each television programme. The complete terrestrial UHF TV transmitting spectrum covers the frequency range 470-860MHz. This spectrum is split into groups of 8MHz which, are characterised by a set of channel numbers. The following chart shows the relationship between frequencies, groups, channels and aerial colour codes.
UHF TV Frequencies, Groups, Channels and Aerial Colour Codes Frequency 470-606MHz
Aerial Colour Code
Aerial Group
UHF Channel
A
21-37
Red
582-734MHz
B
35-53
Yellow
686-860MHz
C/D
48-68
Green
582-860MHz
E
35-68
Brown
470-694MHz
K
21-48
Grey
470-860MHz
W
21-68
Black
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Television signals are broadcast on different polarities. Main high power transmitters broadcast their signals horizontally and aerials, which receive the signals from these transmitters, are mounted with their elements parallel to the ground. Relay transmitters generally broadcast their signals vertically and aerials, which receive these signals, are mounted with their elements parallel to the mast/vertical to the ground. Additional services broadcast from the transmitter along with the normal analogue TV signal include Digital Nicam stereo sound and analogue Teletext. The Nicam signal arrives at the television in a digital format, which is then reproduced as compact disc quality sound. To receive this improved quality sound you need a television that has a Nicam facility. Analogue Teletext can be called up from the remote control and is much like a newspaper with up-to-date news, the latest sports results as well as extra information
Horizontal mounting
about specific programmes. The service is available on all TV stations. Fastext allows you to instantly call up the page information required by using a series of coloured buttons on the remote control. Digital Terrestrial Broadcasting Digital broadcasting is a more efficient way of transmitting television services, allowing much more information than before to be transmitted. Digital terrestrial television offers:
More programmes a mixture of
new free programmes such as BBC News24, BBC Choice, ITV2 and pay TV programmes from the licensee, ONdigital. Existing analogue programmes BBC, ITV, Channel 4, Channel 5 and S4C. Sharper and clearer pictures with cinema quality, widescreen programmes. Improved CD quality sound. Digital Teletext a greatly enhanced version of the analogue service. It is faster and has refined graphics, with clearer text, more colour and photographs. On screen electronic programme guides to help the viewer select and personalise their viewing choice. Interactive services.
Digital terrestrial television broadcasting uses the same UHF frequency spectrum (470-860MHz) and transmitter network as analogue broadcasting and gives coverage to most of the UK. It is planned to transmit digital signals from 51 main transmitter sites and 30 lower power relay stations. Further relay 5
Vertical mounting
transmitters may be added later. The power output of a digital signal is typically one hundredth the strength of an analogue signal. Digital broadcasting can transmit much more information than the analogue system by converting sound and pictures into binary digits (zeros & ones) or bits. These bits are then compressed so that only the data needed to pass on the difference between each picture frame is sent, cutting out repetitive information and improving quality. As digital technology makes better use of the available airwaves, it allows several programmes all with high quality sound and vision to be squeezed in the same TV channel, occupied by one analogue programme. Digital terrestrial television programmes are currently delivered via six frequency channels or multiplexes, each carrying 4-7 TV programmes. In order to fit the new channels alongside the existing analogue channels without causing interference, each multiplex may have a different power. Service areas for digital transmitters may differ with existing analogue coverage and between different digital multiplexes. For some transmitters multiplexes 5 and 6 may be radiated at lower power than the others and hence are expected to have a poorer coverage than multiplexes 1 to 4. The multiplexes are operated by the public service broadcasters (e.g. BBC, ITV, Channel 4 and Channel 5) and ONdigital who together offer a mixture of free and subscription channels.
With digital reception, the picture will either be perfect or non-existent. The digital cliff refers to the rapid change from the picture and sound being perfect to disappearing altogether. There will be no weak, snowy pictures. Where possible, channels close to those used for the analogue services have been used. This allows the same receiving aerial to be used for the digital signal. A reasonable picture on the existing aerial is a fair guide to successful reception of digital. In some areas of the country the digital signals are transmitted out of group to the current analogue signals. In these cases, a new wideband UHF TV aerial may be necessary for reception of the digital services. In fringe and overlap areas you may need to change your aerial direction and point it at a different transmitter to receive a
satisfactory digital service. Contact a professional aerial installer for further information.
If you wish to receive ONdigitals subscription programmes you will need a smart card and to subscribe ONdigital.
To receive a digital terrestrial signal, you will need either a digital terrestrial set-top box receiver or an integrated digital television with a built-in terrestrial decoder. A digital terrestrial set-top box receiver is used with your existing analogue TV. The most basic form of decoder will receive free to air programmes from the existing broadcasters. The basic decoder will also have an electronic on-screen programme guide to guide the viewer through the multitude of options available and enhanced digital Text pages with high resolution graphics. The settop box will be easy to set up and will link to the TV, VCR and aerial socket and be operated by a remote control.
It is the long-term goal of the government to switch off analogue transmissions sometime in the future and transfer all television channels to digital frequencies, however, this is not likely to happen until 2006-2010. In the meantime the BBC, ITV, Channel 4 and Channel 5 must simulcast i.e. transmit 80% of their programmes both as analogue and digital.
Centre cut out Centre cut-out where the sides of the widescreen picture are cropped.
Letter box Letterbox format, with black bands at the top and bottom of the screen.
Zoomed Zoomed or stretched where the picture is expanded to fill the full screen.
Pillar box Pillar box format with black bands on either side of the screen.
For digital transmissions, all the main broadcasters have given their commitment to making and transmitting widescreen programmes. The screen proportion is 16 units wide and 9 units deep, rather than conventional proportions of 4 units wide and 3 deep.
Viewing a 16: 9 image on a 4:3 screen
Original 16:9 image A widescreen television will give you the best digital rendition of the new medium. However, if you dont have a widescreen TV, you will still be able to see digital widescreen broadcasts as either a centre cut-out or letter box format.
Viewing a 4:3 image on a 16:9 screen
Original 4:3 image To watch older 4:3 pictures on a widescreen TV, you will be able to view either a zoomed or stretched format
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SATELLITE & CABLE TELEVISION BROADCASTING
Analogue Satellite Broadcasting Satellites, which relay TV signals, are positioned in different orbital positions at a distance of 35,615km above the earths equator. A satellite positioned at this distance takes 24 hours to orbit the earth and is said to be in geostationary orbit, as it is always in the same position above the earth. In Europe, Astra and Eutelsat are two of the main TV broadcasting satellites. The Astra analogue satellites are co-located at the orbital position 19.2° East above the equator and the main Eutelsat TV Satellites are located at 13° and 16° East.
W
E
60°
60°
40°
40°
20°
20° 0°
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Satellite operators transmit their signals at a very low power from large parabolic aerials on the ground to the satellites. The satellite then amplifies these signals, converts them to a different frequency and transmits them back to earth towards your satellite dish. Each satellite has many transmitting antennae, which transmit different channels or programmes to different European regions. The transmitting ray of a single antenna is called a beam. This beam that reaches the earth is called the footprint. Signals are stronger in the centre of the footprint, getting weaker towards the edge. To receive a satellite signal you will need a dish which is a suitable size and shape, LNB and analogue satellite receiver. Reception of satellite signals is covered in greater detail in the Satellite Installation section. Digital Satellite Broadcasting In the UK digital satellite television from BSkyB launched during 1998 with near nationwide coverage. BSkyBs digital satellite television service offers hundreds of channels, a mixture of new basic and premium services, including a large number of subscription and pay per view services, near-on-demand movies (the same title starting every 10 or 15 minutes) and enhanced football coverage. BSkyB also offers new interactive services initially via a telephone modem in conjuction with British Interactive Broadcasting.
BSkyBs digital satellite television service is beamed down from the Astra satellites located at the orbital position of 28.2° East. If you already have a satellite system and wish to receive BSkyBs digital satellite signals. You will need a new BSkyB digital satellite set-top box receiver or a new integrated digital television with built in digital satellite television decoder. You will also probably have to change your dish to a smaller digital dish and you will need a new LNB. For digital satellite reception the dish must be positioned for the new orbital position, so if you still wish to receive the existing analogue (non-BSkyB digital services) and new digital signals then
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you will need two satellite dishes. See Satellite Installation section for further information on reception of digital satellite signals. Digital Cable Broadcasting Digital cable television was launched nationally during 1999 and offers hundreds of new channels. Digital cable television is transmitted via the existing cable TV lines and is operated by the major cable organisations. You will need a new digital cable set-top box receiver linked to your current television or new digital television with built in digital cable receiver/ decoder. For further information, contact your local cable operator.
RADIO BROADCASTING
Radio In the UK there are currently five BBC national networks, Radios 1,2,3,4 and 5 Live and three regional networks, Radio Scotland, Radio Wales and Radio Ulster. In addition to this there are approximately 40 BBC local stations in England. There are also independent national networks, such as Classic FM, Virgin and Talk Radio, which are controlled by the Radio Authority. In addition there are over 200 local independent stations ranging from regional stations, to local stations covering a single city or area. These radio stations are spread across the AM, FM, DAB and Satellite Radio spectrum.
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AM Radio Broadcasting AM (amplitude modulation) is used to describe the long wave (LW) and medium wave (MW) bands. AM radio signals are broadcast from national and regional transmitters covering the frequency spectrum 153-1602KHz. The signals are transmitted in an analogue format where radio waves directly represent the original sound. AM radio signals offer convenient sound, however can be easily affected by the weather. For higher quality sound choose FM or DAB. FM Radio Broadcasting FM (frequency modulated) radio signals are broadcast from regional transmitters covering the Band 2 frequency spectrum from 88-108MHz.
The signals are transmitted in an analogue format and offer high quality stereo sound. On the FM waveband, local and national stations are interleaved along the frequency band and different frequencies are required to broadcast a single programme over a large area. For example the table shows that BBC Radio 1 broadcasts on several frequencies between 97-99MHz. Retuning is necessary throughout the country. Digital Audio Broadcasting Digital technology has also revolutionised radio broadcasting with the first pilot Digital Audio Broadcasts appearing in September 1995. Near universal coverage of the UK is the longer term objective, as with analogue television, the long-term goal of the government is to use the analogue spectrum for other applications. Digital Audio Broadcasting or Digital Radio as it is more usually referred to converts digital speech, music and data signals into binary digits to resist interference and to transmit information more efficiently allowing more programmes to be broadcast. Digital Radio has the following benefits over FM and AM radio:
Reliable, interference free reception on all receivers e.g. Hi-fi systems, car radio and portable radio. CD quality sound. No retuning-same frequency is used for programme nationwide (Single frequency network). More programme choice. New services-text, graphics and still pictures.
In the UK Digital Radio broadcasts in the Band 3 spectrum between 217.5 MHz and 230MHz, split into seven 1.55MHz blocks called multiplexes. The multiplexes provide 8 national BBC radio stations, 8 national commercial radio stations and 16 different local stations.
Frequency (MHz)
108 Local radio stations* 102 Classic FM 99.8 BBC Radio 1 97.6 Local radio stations* 94.6 BBC Radio 4 92.4 BBC Radio 3 90.2 BBC Radio 2 88 Table shows frequency range for national FM radio stations. *For specific local FM radio stations see your area programme listings guide.
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To receive digital radio, you will need a digital radio receiver and a digital radio aerial. You may not need a directional antenna in the loft or on the roof to achieve the best results, as with FM. With digital radio, you either get an error-free sound and data signals or if you are outside the reception area, nothing at all. Satellite Radio Broadcasting In Europe, two of the main satellite television broadcasters, Astra and Eutelsat, also broadcast UK national and regional radio stations both from the BBC and independent broadcasters, alongside satellite TV stations. As with analogue satellite television, Astra broadcasts analogue radio from the orbital position of 19.2° East and Eutelsat broadcasts from the Hotbird satellite 13° East. Digital radio is currently broadcast from Astra at the orbital position of 28.2° East. Radio services via digital satellite provides:
quality sound. Digital Near nationwide digital radio coverage. Increased choice of radio services. Regional programmes available near nationwide. Selection of exclusive digital radio services. To receive satellite radio, you need to have an appropriate satellite receiver, either analogue or digital depending on the service to be received, connected to a satellite dish. The majority of satellite radio stations are free to air and require no subscription. Satellite radio stations can either be played through the televisions speakers or connected to a Hi-fi for improved quality sound. Internet Radio Broadcasting Many radio stations now have internet web sites and make their radio or audio services available via the web. To receive Internet Radio you need an internet connection supplied by an Internet Service Provider, a computer with a modem and sound card, world wide web browser software and streaming audio software. A good quality sound card and speakers will be required to appreciate the Hi-fi sound reproduction available via the internet. Music can be customised and downloaded onto MP3 style players for listening at a later date.
TERRESTRIAL TV AERIALS
Types of UHF TV Aerial There are three basic categories of UHF TV aerial: 1. External/Loft Aerials For DIY installations, wideband (group W) television aerials are readily available and may be used for reception of all UHF TV channels. Their usage will increase significantly with the advent of Digital Terrestrial Television.
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Grouped aerials (group A,B,C/D,E,K) see chart page 4 are generally available from more specialised outlets and are usually fitted by professional aerial installers who have knowledge of the local transmitters. They receive specific channels and due to a narrower bandwidth are of a higher gain than wideband aerials.
Reflector
14 element UHF TV aerial Insulator cap
Clamp
Elements
Dipole
Boom
18 element UHF TV aerial
Mast
Coaxial cable 10 element UHF TV aerial
For the best reception, it is recommended to mount your aerial externally in as high as a position as possible. Aerials can be mounted in the loft space or on an outside wall, but in weak signal areas or where trees or large buildings cause obstructions picture quality may be reduced and an external aerial should provide an improved signal. See Terrestrial TV Aerial Installation section for further information. In addition, the aerial should also be of good quality with sufficient elements (crossed strips) to deliver enough signal to your television. When looking for an aerial there is usually a
and will receive more of the incoming signal to provide the best possible television picture in a weaker signal area. For reception of digital terrestrial signals a larger element aerial may be required. Aerials are also available in kit formats for DIY assembly which come complete with mast, cable and fixing accessories.
are supplied with internal or external signal boosters. They do not need alignment or adjustment when travelling from location to location. For digital reception directional aerials are recommended as they pick up more signal and offer greater rejection to unwanted signals than omnidirectional aerials.
For touring applications, directional and omnidirectional aerials are available. Directional aerials such as the Mobile Gold, must be pointed towards the transmitter and need to be realigned at every new location to receive a signal. Adding a signal booster can improve TV reception. Omnidirectional aerials, such as the Omnimax and Gazelle, receive all available signals throughout UHF TV aerial Omnimax mobile aerial
choice between 10 element, 14 element and 18 element UHF TV aerials. Generally the larger number of elements, the more is received by the aerial. A high gain UHF TV aerial has more elements than a standard aerial 12
43 element high gain UHF TV aerial
23 element high gain UHF TV aerial
UHF TV aerial kit
Mobile Gold mobile aerial
High gain UHF TV aerial
!
2. Indoor Aerials In strong reception areas a set top or indoor aerial can be used to receive terrestrial television signals, however, the best quality reception will always be obtained using an external aerial, mounted either on the chimney or wall. Set top aerials will however improve signal reception to televisions which cannot receive a signal from an external or loft mounted aerial, or compared to built in loop aerials. They are often used with portable televisions in bedrooms etc. Set top aerials are wideband aerials and are capable of receiving all available UHF terrestrial television signals from the local transmitter. As TV signals available inside a room are variable ensure the aerial has a length of coaxial cable long enough to move the aerial to the best possible reception position. There are two types of indoor aerial. The first is a directional, which you point towards the transmitter and move around the room to find the best signal. The Truvision, Horizon and Contour are all examples of good quality directional indoor aerials. If the signal is weak, you should choose an indoor aerial with good low noise amplification such as the Contour Plus which has an integral battery operated signal booster or the Horizon Plus or T-Vision which both have separate
mains powered Signal Boosters. The gains of these Maxview signal boosters have been optimised for reception of digital terrestrial UHF TV signals. The second type is an omni-directional, which receives all the available signals throughout 360 degrees, but still needs placing in the best possible position in the room. The Omnivision receives all available UHF TV and FM signals throughout 360 degrees and comes complete with a separate fixed gain signal booster with variable gain on the antenna section.
by external interference and usually gives unsatisfactory results. An indoor aerial for example Truvision, or Horizon will give improved reception compared to a built-in loop aerial.
Telescopic TV aerial
3. Built-in Loop Aerials A built-in loop or telescopic aerial, normally supplied with the TV, is the least effective of all the aerials as it has low gain and is fixed in position in the room (on the back of the television set). It is capable of receiving all of the available signals but is easily affected Built-in loop TV aerial
Horizon directional TV aerial
Truvision directional TV aerial
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Contour Plus directional TV aerial with signal booster
TERRESTRIAL TV AERIAL INSTALLATION TV Aerial Installation The best reception is always obtained when the correct type of aerial is installed in an outside position, high enough to clear local obstructions and pointing in the direction of the transmitter. Aerial height may need some final adjustments to give the best reception on all terrestrial channels. The following guidelines will ensure you can achieve the best possible reception. Loft fixing
600mm
TV Aerial Position Before installing a new aerial check that your existing mast is in good condition. If you are adding an additional TV aerial ensure that the mast is long enough to allow a minimum vertical
separation of 600-650mm (2ft approx) between the two UHF TV aerials. To receive the best interference free reception it is essential to fit the aerial as high as possible, free from obstructions. It is recommended that the aerial is mounted externally on a mast, on the eaves or on an outside wall or balcony. If you do not have external access the aerial can be mounted in the loft but the picture quality may be
Wall fixing Chimney fixing
dramatically reduced compared to external mounting. For analogue reception, correct positioning of aerials is particularly important for reception of digitally-coded analogue signals such as Teletext and Nicam. Ghosting caused by reflected signals, which may not be noticeable on normal television pictures, can cause errors or missing letters in text on screen. For digital terrestrial reception the aerial position is very important to ensure that there is no signal drop out. The digital cliff refers to the very rapid change from perfect pictures and sound to non-existent pictures or sound.
Eaves fixing
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Chimney, Wall and Loft Fixing Kits are all available to provide the best fixing for chosen mounting location. TV Aerial Orientation Ensure the aerial is mounted either vertically or horizontally to match the polarity being broadcast from the chosen transmitter. Incorrect polarity can easily result in only picking up a quarter of the signal as well as being susceptible to some forms of interference. Refer to a transmitter guide to check polarity or look at your neighbours aerials. Wall fixing kit Horizontal mounting
Vertical mounting
Chimney fixing kit
TV Aerial Alignment To get the best signal the aerial must be accurately aligned. There is a simple three step alignment procedure for the best analogue reception: 1.Turn your aerial to the LEFT until the picture is lost. 2.Remember this position and turn the aerial to the RIGHT until the picture is lost. 3.Now point the aerial in the centre of these points to receive the best reception.
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This alignment will not work for digital signals as with digital the picture and sound are either there or not there. There is no gradual degradation of signal. To tune in digital signals, first tune in the analogue channels and then refer to the manufacturers instructions of your digital terrestrial equipment for further guidance. You may need to call in a professional aerial installer or ONdigital for advice.
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1
TV Aerial Downlead To minimise any signal losses between the aerial and the TV, it is essential to use the shortest possible practical lengths of good quality screened coaxial cable. There should be no sharp bends in the cable and to avoid crushing of the cable any cable clips should not be hammered home too far. TV Aerial Connections These must be correctly terminated with tight connections on the outer and inner at both the aerial terminals and TV plug end of the downlead. 16
Types of Satellite Antenna System There are two basic categories of satellite antenna system:
SATELLITE
ANTENNA
1. Domestic Satellite Antenna Domestic satellite antenna are normally installed either on a mast, the chimney or wall or alternatively strategically placed in the garden to camouflage the dish. 2. Touring Satellite Antenna Touring satellite antenna are used for touring vehicles such as caravans and motorhomes. They are available to either fix permanently on a through the roof fixing or to be used together with a mast or tripod fixing. The main advantages of a permanently fixed through the roof mounted satellite system is that all alignment and adjustment can be made from inside the touring vehicle when you want to watch satellite. The more advanced permanently fixed satellite systems have an electric motor which enables the dish to raise automatically and self seek the satellite. SATELLITE INSTALLATION To receive a satellite signal you must be within the coverage area or footprint of the satellite. Other criteria which must be considered are the shape and size of the dish, the surface area, the reception angle, rejection of signals from unwanted satellites and ease of alignment. Coverage The predicted coverage of a satellite signal is shown by a footprint. Satellite footprints show under optimum weather conditions i.e. clear skies, no rain, cloud etc. the signal strength (dBW) required to receive a picture in a certain location. Satellite signals are stronger in the centre of the footprint getting weaker towards the edge. Clouds, rain or snow decrease the signal strengths and with analogue signals picture distortion in the form of black and white sparklies can appear. In severe weather conditions this can result in a complete loss of picture. With digital signals the picture and sound block or disappear. It is also important to bear in mind that not every channel received
from the chosen satellite will be received with the same signal strength. Dish Size, Surface Area and Reception Angle The choice of dish size is dependent on your location in the UK and hence the signal strength in the area in which you wish to receive the signal. The weaker the signal the larger the dish size required to receive a picture.
Larger dish sizes will be needed in Scotland, the north of England and areas which receive a high rainfall. The size of the dish also effects the surface area and reception angle of the dish. Larger dishes have greater surface areas and therefore can receive more signal. For example, a 48cm dish has 53 per cent more surface area than a 38cm dish and therefore receives 53 per cent more signal.
45dBW 48dBW 50dBW 52dBW
Dish Size
Signal Strength
38cm
52dBW
48cm
50dBW
60cm
48dBW
80cm
45dBW
80cm 60cm
48cm 38cm
38cm
+53%
+150%
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60cm
48cm
+63%
60cm
+100%
In adverse weather conditions, degradation in picture quality is not as obvious with a larger dish, providing both dishes are accurately aligned. Smaller dishes have larger reception angles than larger dishes. For example, a 38cm offset dish has a reception angle of 5° whereas a 60cm dish is only 3°. With larger reception angles, it is easier to locate the satellite and dish will only need fine adjustment. However, a smaller reception angle will give greater immunity to interference from adjacent satellites and receive more signal.
22 24 26 28 30 32 34 36 38 40 42 44
Dish Alignment and Adjustment To receive a clear satellite picture the dish must have the correct Vertical (or Azimuth) and Horizontal Alignment. Vertical alignment is the dish angle of elevation and refers to the angle at which the satellite signals hit the earths axis. In the northern hemisphere they are flat - about 15° and the further south you go i.e. nearer to the equator, the steeper they become. On Sicily they have an elevation angle of 45° . Horizontal alignment is the position of a satellite relative to where you wish to receive the signal and requires the dish to be turned until the satellite signal is received. For analogue satellite reception, first make sure that your television is tuned to the output channels of the satellite receiver and that the receiver is tuned to a known Astra or Eutelsat satellite 18
channel. Correct dish alignment can be helped with the use of a basic compass. Once the dish is aligned left to right with the compass bearing (e.g. Astra 1 satellites are located at 19.2° East of South and Astra 2 digital satellites at 28° East of South), the dish can then be adjusted to the correct vertical elevation. Using the TV picture as a guide, slowly elevate the dish until a clear picture is found. Alignment is fairly critical and the dish must be within a few degrees before any picture or sound will be observed. If after elevating the dish the picture is still full of sparklies you may then need to fine tune the bearing of the dish by slowly moving the dish from left to right and/or vertically until a clear picture is found. When tightening the dish mounting bolts take care not to move the dish position. For digital satellite reception, the dish alignment is basically the same as with an analogue system. Instead of using the picture as a guide most digital satellite receivers have a signal strength meter built into them. Also move the dish in slow discrete steps in order to allow time for the digital meter in the satellite receiver to respond correctly. Consult the manufacturers instruction manual for more details. LNB and Satellite Receiver The signals are then focussed by the dish to strike the focal points within the Low Noise Block (LNB). The High and Low Band are selected by a 22KHz tone and vertical and horizontal signals from the satellite are selected by changing the voltage supplied to the LNB from the receiver. These signals are then converted to a lower frequency between 950-2150MHz which can be sent down the coaxial cable to the receiver. If you already have a satellite system it is possible to upgrade your LNB to provide improved picture reception, or receive more channels. This can be done by installing an enhanced or universal LNB. A twin LNB has two outlets that enable two satellite receivers to be fed from one dish. The satellite receiver is the final part of the chain before the TV and is where all the signals that are collected by the dish are converted into a format that the television can display. This is also the unit into which a decoding (Sky TV) card is inserted to allow you to watch your subscription channels.
RADIO AERIALS
Omnidirectional dipole FM aerial
Types of FM Aerial There are three basic categories of FM aerial: 1. External Aerials An externally mounted FM aerial will supply your Hi-fi system with the best possible FM radio signals. There are two main types of FM aerial for external use directional and omnidirectional aerials.
Omnidirectional FM aerials
Directional aerials must be pointed directly towards a single transmitter to receive the signal such as a dipole mounted horizontally. Directional high gain FM aerials are also available from professional aerial installers. Omnidirectional aerials, which can be either a straight dipole mounted vertically or a C-shape mounted horizontally, receive signals throughout 360 degrees. The quality of reception is slightly less than that from a directional aerial, but the advantage is gained when wanting to receive more than one FM transmitter signal. 19
Directional FM aerials
2. Indoor Aerials If you are unable to fit an external or loft FM aerial, an indoor aerial combined with a signal booster is the next best option. The Profile Plus is a good quality indoor FM aerial designed to provide a good quality signal and to co-ordinate with modern Hi-fi systems. 3. Built-in Aerials There are two other types of FM aerial, which are usually supplied by the equipment manufacturer. One is a T shaped piece of plastic coated wire, which when laid in position has the same characteristics as the dipole shown on the previous page (both omnidirectional and directional). The second is a telescopic type aerial, which is fitted directly to the rear or top of a portable FM receiver. Both types of aerial are affected by interference caused by people moving close to it and are the least effective of FM aerials.
DAB Aerials To receive digital radio, you will need a digital radio receiver and a digital radio aerial, but you may not need a directional aerial in the loft or on the roof to achieve the best results. With digital radio, you either get an error-free signal or if you are outside the reception area, nothing at all. If you need an aerial for Digital Radio a VHF aerial which covers the Band 3 between 217.5-230MHz is recommended. 20
Signal Boosters and Masthead Amplifier products are designed to amplify UHF TV and FM radio signals and distribute TV, Radio, Video and Satellite signals. A Signal Booster is the term used for a DIY unit used to boost or distribute a signal. It is either placed in the loft, in a convenient position in the house, or behind the main TV set.
SIGNAL BOOSTERS & MASTHEAD AMPLIFIERS
In the very weakest reception areas a high gain aerial and masthead amplifier will be required. A masthead amplifier is more likely to be used by a professional aerial installer and is installed on an external TV aerial mast. The amplifier receives d.c. power from a masthead power supply unit located indoors. This unit is mains powered and connects between the amplifier and TV, providing the best possible signals for TV and FM radio. Signal Amplification In many areas, the incoming TV signal may be quite weak and although a larger element aerial may be used, the TV signal may still need some improvement.
This sort of problem can often be overcome for both television and radio with the use of a signal booster which amplifies the incoming signal and can be split at the outgoing
socket to TV and/or FM radio. A booster may also give an improvement where long lengths of coaxial cable reduce signal power.
Signal booster TV TV TV TV TV Video
Signal booster
Signal booster installed in loft (video to 1 TV)
Signal booster installed in room (video to 3 TVs)
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Video
TV receiving digital signal
TV receiving digital signal
TV receiving digital signal
TV receiving digital signal
TV aerial Video recorder FM aerial
Signal booster TV/FM diplexer
TV/FM diplexer
TV/FM diplexer
TV/FM diplexer
Digital terrestrial set top receiver
Hi-fi
TV/FM diplexer
Hi-fi
Hi-fi
Hi-fi
TV, FM, Video and Digital to all TVs
For amplification of digital terrestrial television signals, it is important to use a low noise signal booster with low gain and good signal handling. In the distribution chain, the digital terrestrial television set top box should be placed before the video, digital satellite receiver or analogue TV to minimise degradation of the digital terrestrial signals. Signal Distribution Signal boosters can also be used to distribute analogue and digital UHF TV, FM Radio, DAB, Video and analogue and digital Satellite outputs to many outlets around the home without loss of quality. To ensure the best quality signal distribution, ensure the booster is located as close to the TV and/or FM aerial as possible. When distributing a digital terrestrial signal and existing analogue signals around the home, like with satellite, you will only be able to distribute the programme, which is selected on the set top box receiver.
In strong signal areas, a splitter may suffice to split a signal for distribution. See Combining and Splitting Signal section for more information. Types of Signal Booster There are two basic categories of indoor signal booster: 1. Fixed Gain Signal Boosters The fixed gain signal boosters come in a range of 1,2,3,4,6 and 8 outlet models. The 1,2,3 and 4 set models are designed to be plugged directly into a convenient 13amp mains socket, making them ideal for installing close to the TV or audio equipment.
These models are ideal for smaller domestic installations. The 6 and 8 set models are fitted with a mains lead and plug, enabling them to be located away from the mains socket. These models are generally used in larger installations or for flats and offices. 2. Variable Gain Signal Boosters The variable gain signal booster range is available in 1,2,3 and 4 outlet models. The units are fitted with a mains lead and plug, enabling them to be located away from the mains socket. Each model has a variable gain control allowing fine adjustments of the signal strength to achieve the best possible picture and sound quality. For further information regarding installations requiring more than 8 outlets or for integrated digital televisions contact the Maxview Customer Helpline.
Signal booster with variable gain control
Plug in signal booster
Fixed gain signal booster in loft
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ACCESSORIES
TV, Radio and Satellite Accessories Coaxial Cable and RF Connectors When one end of a coaxial lead has been connected to an aerial (TV, Satellite or Radio) you will usually need to connect a RF connector to the other end for it to plug into your television, satellite receiver or Hi-fi. There are two main types of RF connector. The one used in the majority of cases is a screw together
and push in type, called a coaxial connector. The second is a screw on and screw in type, called an F connector, mainly used for satellite, cable, professional use or for mobile vehicles where a secure fixing is needed that will not disconnect over a long period of time.
There are many different types of coaxial cable. As a signal travels along the cable, it begins to lose some of its strength. Therefore the best types of cable are low loss double screened or tape and braid which lose the least amount of signal. Usually, the thicker the cable, the lower the loss and the better the screening.
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Fitting a Coaxial Connector 1
First cut cable to required length and then unscrew coaxial plug and slide screw cap over cable. 5
2
3
Strip away about half of the inner insulation around the inner copper wire. Check that none of the copper braid is touching the inner copper wire.
Strip away approximately 23mm of outer insulation. Next, gather strands of copper braid together and wind back around the outer insulation.
* If cable is tape and braid, cut tape to be flush with outer insulation
Screw cap
Outer insulation
Cut off inner copper wire flush with plug.
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Copper braid
Inner insulation
Open claw, slide over copper screening and pinch to tighten. Loosen screw in plastic connector slide over inner copper wire. Tighten screw* securely ensuring head of screw does not protrude above plastic. Do not over tighten. Reassemble coaxial plug
* If plastic connector does not have retaining screw, an effective connection will still be made by re-assembling the plug.
Brass claws
Push-in type connector
Inner copper wire
Centre stem
Copper braid Inner insulation
Outer insulation
TV aerial
Tape
TV aerial
TV 2 way splitter/combiner
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Inner copper wire
Combining and Splitting TV Signals Signals from two different regional analogue transmitters, broadcasting different regional analogue TV programmes, can usually be combined into the same downlead cable using a TV 2 Way Splitter/Combiner. A TV 2 Way Splitter/Combiner can also be used to split analogue or digital TV signals to 2 outlets, however this is only recommended in a strong signal area, as splitting reduces the strength to each outlet. Strong FM or DAB signals can also be split in the same way.
Fitting an F Connector 1
2
First cut cable to required length.
3
Strip away approximately 15mm of outer insulation. Next, gather strands of copper braid together and wind back around the outer insulation.
Strip away about half of the inner insulation around the inner copper wire. Check that none of the copper braid is touching the inner copper wire.
* If cable is tape and braid, cut tape to be flush with outer insulation
5
4
Feed the inner copper wire through connector and screw clockwise to tighten.
Outer insulation
Inner insulation
Inner copper core
Copper braid
Cut off inner copper wire to extend 3 mm beyond plug body.
TV aerial
Screw on F connector
Combining and Splitting TV and FM Signals If you have both a TV and FM aerial, it is also possible to combine both of these signals into one downlead cable, using a TV/FM diplexer. A diplexer unit contains electronic components, which combine two signals with maximum efficiency. When a diplexer is used to combine TV and FM signals it stops FM sound affecting TV pictures and vice-versa and when used to split signals, it maintains equal signal strength to both TV and FM outlets.
FM aerial
TV/FM diplexer
Strong TV, FM or DAB signals can be split to 3 outlets using a TV/FM 3 Way Indoor Splitter. 25
Types of Outlet Socket 1. Flush Mounted Outlet Plates If you are installing a complete home distribution system and have easy access to the wall, flush mounted outlets are the best way to supply TV and FM to each room. Flush mounted outlets fit on a standard 25mm deep single metal mounting box, which is recessed into the plaster. Alternatively they can also be mounted on plastic surface mounted boxes.
TV aerial
A TV/FM Diplexed Outlet Plate is the most effective outlet plate as it electronically splits the signal from a single downlead cable to one TV and one FM outlet with minimum loss of signal quality. If only a TV aerial is used at present, it still allows a FM aerial to be installed at a future date, provided a TV/FM diplexer is put in the loft.
FM aerial TV/FM diplexer
For a single TV or FM downlead Single Flush Outlet Plates are available and Twin Flush Outlet Plates for two separate TV and FM downleads. Flush outlet plates are also available for satellite with a single female F socket and a dual downlead version for satellite and TV with a female coaxial socket and female F socket. 2. Surface Mounted Outlet Boxes If you have surface mounted the coaxial cable, use surface mounted outlet boxes. For a single TV or FM downlead a Single Surface Outlet Box can be used. A TV/FM Twin Surface Outlet Box contains a resistive splitter so a single downlead can feed two separate TV and FM outlets. In situations where two different TV (or two FM) aerials, receiving separate transmitter signals come into a house, a switched type box could be used. This allows manual switching to receive each transmitter separately if difficulties arise in combining two aerials. Alternatively a diplexer could be used to combine the two signals. For information on combining aerials contact Maxview Customer Helpline.
Coaxial plug into TV
TV/FM diplexed outlet plate
Coaxial cable connection
Connecting Coaxial Cable in Outlet Socket Cut cable to required length. Strip away approximately 23mm of outer insulation. Next, gather strands of copper braid together and wind back around the outer insulation. Strip away about half of the inner insulation around the inner copper wire. Secure the inner copper wire 26
beneath the screw down terminal, and tighten the circular metal clamp down over the copper braid. Trim the inner flush with the centre screw and make sure no strands of braid are loose and able to touch the central core and short out the signals. Then fit the cover of a surface mounted outlet or screw the faceplate of a flush mounted one to its mounting box. To connect from the outlet socket to the Television, Radio, Satellite Receiver or Cable Box, fly leads (or extension cables) are available in 2m, 4m and 10m lengths with either coaxial or F type connectors.
TV or FM single flush outlet plate (1 in, 1 out)
TV or FM twin flush outlet plate (2 in, 2 out)
TV or FM single surface outlet box (1 in, 1 out)
TV/FM twin surface outlet box (1 in, 2 out)
TV/FM diplexed outlet plate (1 in, 2 out)
TV or FM switched surface outlet box (2 in, 1 out)
Audio/Video Accessories Audio/Video Connections Audio/Video accessories are used to enhance the sound and picture quality of your equipment. There are basically two types of audio/video connector scart and phono. Scart Connector This method of connection was designed as a European standard that would allow equipment to communicate directly with each other and improve picture quality. When a scart connector is plugged into a TV, Video or Satellite receiver, the signal travels
process which occurs if coaxial plugs and cable are used to connect equipment via RF leads. A standard scart to scart lead has 21 individual connections carrying different signals. Many of the pins are opposite to each other, this allows a lead to be connected either way round. You may need to select the A/V mode on the equipment to choose the scart path for the signal, if the equipment does not auto select. Phono Connector Most TV, Video, Satellite and Hi-fi systems have phono connectors for convenient interconnection of sound or vision signals between equipment. A phono connector plug carries the equivalent to 1 of 21 pins in a scart plug. Scart to Phono Connector If new and older equipment are being used together it may require a scart to phono connector lead.
Scart connector
between them via the most direct route possible. This ensures high quality picture and sound are maintained, avoiding the translation
Surround Sound There are a number of different types of Surround Sound offered by equipment manufacturers, the main ones are Dolby* Surround and Dolby* Pro-Logic. Surround offers two speakers at the front and two at the rear. Pro-Logic however offers two speakers at the front and two at the 27
rear and an additional centre speaker at the front. With both systems the two front speakers supply stereo sound and the two rear speakers create special affects. The centre speaker with Pro-Logic carries the dialogue from the actors on screen. *Dolby is a trademark of Dolby Laboratory Licensing Corporation.
Phono connectors
If your equipment doesnt have surround sound, but your television and video has either scart or phono connectors, it is possible to produce it via the Hi-fi.
Universal Remote Controls There are two basic categories of Universal Remote Control: 1. Replacement for Lost or Broken Remote Control The most basic one way universal remote controls are intended as replacements for lost or damaged original manufacturers handsets. This is often a much cheaper alternative than purchasing a manufacturers own direct replacement remote control. 2. Multiway Replacement Multi-function units can be used to replace multiple handsets to allow you to control for example your analogue or digital TV, Video, Satellite receiver or cable box even Hi-fi from one handset. The universal remote controls may also have additional features which include:
Cassette cleaning kit
Video cleaning kit
Direct buttons for digital terrestrial television and digital satellite television functions.
Each universal remote control contains a micro-chip that holds a library of infra-red codes. These codes cover the vast majority of equipment sold in the UK. All you have to do is enter the makers code for each piece of equipment to be controlled, store the code and it is ready to use.
CD lens cleaning kit
Cleaning Kits Cleaning Kits are available for Cassette, Video and CD Lens to maintain the performance of your equipment. For the best results they should be used on a regular basis. Headphones To enjoy the sound from your audio equipment such as TV and Hi-fi without disturbing others, headphones are available in three basic categories of in-ear, open and closed back.
Timers and programmable AV system controls. Macro functions, which can switch
on and configure two or three devices with a single button press. Learning facility for any type of infra-red equipment for example a Hi-fi or even garage doors. The learning facility allows the Remote Control to be taught the function of another remote by placing them head to head and setting the keys. The original remote control must be available for the new unit to learn its information from and these units can only learn functions that your original remote control was programmed to accept.
Open stereo headphones
In-ear headphones
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Closed stereo headphones
Analogue Terrestrial TV Snowy Picture A generally faint or grainy television picture, often referred to as snow, is generally caused by a weak signal. Normally the TV transmitter will be a long way away. A possible improvement could be made by reducing the aerial downlead losses, installing a high gain aerial and by adding a low noise masthead amplifier or signal booster. In a small number of cases a snowy picture can also be caused by too strong a TV signal, customer services will provide assistance. Herringbone Pattern Herringboning is generally caused by a too strong TV signal or possibly by a local high power transmitter such as CB Radio, radio amateur or radio taxi. Your TV sound may be affected as well as the picture. Contact the Radio Authority for further information. Ghosting Ghosting is observed when certain reflected signals are picked up by the aerial in addition to the wanted direct line of sight TV signal from the transmitter. Ghosting will appear as multiple pictures on your screen and is usually caused by reflections from a building or other tall object. If the ghost image moves to and fro, the problem is likely to be reflected signals from nearby trees moving in the wind. Ghosting can only be improved by adjusting the height and/or position of your aerial or by adding a aerial with a larger reflector. Ghosting cannot be improved by adding a signal booster. Co-Channel Interference In some areas of the country and under certain weather conditions you may receive two programmes from different transmitters on the same channel. This may appear as strong horizontal lines on the screen. TV announcements are usually made when the effect is persistent over a wide area. Contact the BBC Engineering Information Department, ITV or the Independent Television Commission. Electrical Interference Interference can occur on both picture and sound. An uneven band of spots or
RECEPTION PROBLEMS lines indicates that the problem comes from equipment like a vacuum cleaner, fan or electrical drill. Try switching the appliance off to see if the interference stops. If it does you have located the source. All modern household appliances are required by law to suppress interference, so contact the supplier of the equipment. A burst of interference caused by the operation of a central heating system timeswitch or fridge/freezer switching on and off. This may also be heard on the sound. It may be necessary to replace the thermostat or switch as these sometimes deteriorate with age, so contact an electrical supplier. If the interference seems to be coming from a neighbours house, approach your neighbour politely. Remember that they may be completely unaware of the interference and that the problem could be that your set is not properly protected against interference. Contact the Radio Authority for more information. Digital Terrestrial TV Unlike analogue TV signals that can still be viewed under weak signal strength conditions, with digital terrestrial signals blocking/freezing and/or loss of digital picture and sound can be caused by insufficient digital signal and carrier to noise ratio. Similarly blocking and even a completely blank screen with no sound can result if the input signal to the set top box is too high. The digital cliff refers to the rapid change from the picture and sound being perfect to disappearing altogether. When interconnecting equipment and to get the best carrier to noise then place the digital terrestrial television set top box as the first item in the signal path followed by any video or satellite receiver. Digital signals are generally immune to ghosting or multipath reflections. They remain perfectly receivable under conditions where an analogue signal would suffer ghosting. For specific help with DTT reception problems contact
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ONdigital and for further general information contact the DTG Group. To improve weak digital terrestrial signals try the following: move the aerial outside, reduce the aerial downlead losses, install a high gain aerial, add a low gain, low noise masthead amplifier or signal booster close to the aerial. Analogue Satellite TV Sparklies Sparklies or horizontal black or white tails on screen, are generally caused by a weak or mis-tuned signal. Examples which may cause a weak signal include the dish moving off-beam, problems in the coaxial downlead, water penetration and deterioration of the LNB. Under severe weather such as heavy rain or snow sparklies may also be experienced. Similar problems can be caused when the receiver is not properly tuned and locked into the satellite channels. Co-channel Interference Under certain conditions co-channel interference results because two programmes that are on the same frequency but from different satellites are received simultaneously. This may appear as a mixture of sparklies and vertical horizontal bars on the screen from the unwanted satellite channel. This is usually caused by insufficient rejection of the unwanted satellite due to the satellite dish being misaligned or too small in size resulting in it having a larger than required reception angle. Digital Satellite TV With digital reception, a weak signal or incorrectly aligned dish will cause the picture and sound to block or disappear. Check both the alignment of the dish and skew angle of the LNB. Intermittent Connections Make sure all RF cable to connector joints are tight (both inner and outer) including all flyleads and outlet plate connections.
Telecoms With the trend towards working from home, there is an increase in communication equipment in the home such as telephones, fax machines, computers and modems to access the Internet. Multi function machines are now available which offer fax, copier, printer, PC-fax, scanner and e-mail from one unit. Telephone There are basically four types of telephone: 1. Analogue Corded The traditional telephone with a fixed cord from the phone base to the handset. 2. Analogue Cordless The first system of cordless technology with limited operating distances. 3. New Frequency Analogue Cordless An enhanced system which uses eight channel technology, a new frequency range of 31-39MHz and gives clearer call and larger operating distance approx. 100m away from the base station. 4. DECT-Digital Enhanced Cordless Telephony DECT phones that use digital cordless technology, operate on 1.8 GHz and allow multiple handsets to be used from a single base station, offering significantly greater range than analogue models, improved reception and clearer speech. Combined mobile/DECT cordless phones, provide mobile and DECT features in one smart handset, which can accept or make calls on both mobile and land line networks. These use DECT protocol close to the home and automatically switch to mobile use outside a certain range. Master socket
TELECOMS & ACCESSORIES Fax Machines Fax machines plug into a telephone socket and have built in software to enable the user to transmit data for instance a letter, which can be received normally by another fax machine. Early fax machines used thermal paper but more modern machines print directly onto standard A4 paper. Internet, Modem and Interactive Services A modem is a device which allows a computer or Digital Set Top Box (STB) to send and receive information over a telephone line. It can be an internal device built into the desktop, laptop, or STB, a separate external box that connects to a computers serial port, or a PC card that plugs into the PC card slot found on most laptops. Modems are available in a variety of speeds, the faster the modem, the quicker the data can be transferred and hence shorter and cheaper the phone call will be. This is provided the telephone line and other end of the line can support the modem speed and protocol.
computer to the digital line you need an ISDN adaptor rather than a modem, and the Internet Service Provider you choose must offer ISDN support. An alternative to the PC-modem-phone line or PC-ISDN approach is to connect through the mobile phone networks, either by linking a laptop to a mobile phone through a data card or an infra-red link. Cable modems and STB modems are often used as the return path for the interactive services offered by the terrestrial, satellite or cable operators. These modems may also offer internet access via the STB.
To connect a modem to a telephone line the socket will need to be a BT style socket. See following section on BT style sockets and installing extensions. Faster access speeds are possible using ISDN digital phone lines, or services such as BT Highway which adds a digital line alongside your existing phone line. To connect your Fax
Extension telephone
Telephone Computer
Junction box Extension cable clipped
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Telephone double adaptor
Telecom Accessories Telephone Extensions Before installing a telephone extension it is important to note the Ring Equivalent Number (REN). Telephones lines have a REN of 4- they can operate up to 4 telephone accessories (e.g. phones, fax, answerphone) each with a REN of 1. An additional telephone extension can be provided by using a multi adaptor or by adding a new telephone extension socket. In more complex systems a junction box may be needed to join up to four lengths of telephone cable end to end.
To convert a single socket to a multi socket outlet, Double and 3 Way Telephone Adaptors are available. It should be noted however, that running more than one lead from a single telephone socket might impair performance of the telephone equipment. The best option is to add in a new telephone extension socket.
are the best way to supply a telephone extension to another room. Flush mounted outlets fit on a standard 25mm deep single metal mounting box, which is recessed into the plaster. Alternatively they can also be mounted on plastic surface mounted boxes.
Extension sockets are added to the existing telephone system from the master socket, which is installed by the Telephone Company such as British Telecom (BT) or Mercury. Extension sockets must not be used as replacements for the existing master socket. There are basically two types of BT master socket:
Flush mounted socket
1. NTE5 socket This type of socket is used on all new BT installations. The lower front half is removable to allow you to connect extensions by hard wiring
2. Surface Mounted Extension Sockets If you do not have access to the walls the most common extension socket is a surface mounted outlet box which is available in either a standard format or a compact version.
2. BT old socket This older type of socket is the former socket used in BT installations. You can only connect extension sockets by plugging in.
Telephone Flush Extension Sockets are available with both single and twin sockets.
Surface mounted socket
NTE5 socket
3 BT old socket
4 If your telephone line is provided by an operator other than BT, your socket may be different to those shown above. Contact the telecommunications operator for further information. Extension Sockets Types of Extension Socket There are two basic categories of extension socket: 1. Flush Mounted Extension Sockets If you are installing a telephone extension and have easy access to the wall, flush mounted extension sockets
5
2
To connect the telephone cable into the back of outlet sockets there are two types of connection available screw terminal and IDC. Screw terminal connections Prepare the cable by stripping away 20-30mm of outer sleeve exposing inner wires. Remove approximately 5mm of inner insulation to expose bare wire. Follow the colour code. Loosen screws, insert wires under screws and lightly tighten ensuring secure connections. IDC terminal connections Prepare the cable by stripping away 20-30mm of outer sleeve exposing inner wires. Do not remove inner wire
IDC cable connecting tool
1 insulation. Following the colour code, lay each wire in the corresponding notch of the connection terminal. Use the IDC cable connecting tool to firmly push the wires into the terminals.
6
Connecting Telephone Cable in Extension Socket When connecting telephone cable in extension sockets the following colour code must be observed: 1 2 3 4 5 6
N.B. It is usual to only use 2,3,4 and 5 for domestic installations.
Green/white ring Blue/white ring Orange/white ring White/orange ring White/blue ring White/green ring 31
Connect the telephone directly into extension socket or to extend the distance from the socket to the telephone, Telephone Extension Leads are available in 2m, 4m and 10m lengths.
USEFUL ADDRESSES A Transmitter Guide containing TV, Radio Transmitters, Channels and Satellite transponders is available from the ITC. If you have any further questions or other information you would like included in a future update of this guide, please write to the Customer Services Department at the address below. Not all the products illustrated in this guide may be available from this retailer. However, they may be available to special order. Ask in store for further details.
BBC Reception Advice Television Centre Wood Lane, London W12 7RJ Tel: (0870) 0100 123 e-mail:
[email protected] website: www.bbc.co.uk/info/reception BBC Digital Radio Room 505, Henry Wood House Langham Place, London WC1A 1AA Tel: (0870) 0100 300 e-mail:
[email protected] website: www.bbc.co.uk/digitalradio NTL Engineering Information Crawley Court, Winchester Hampshire SO21 2QA Tel: (01962) 823434 ITC Engineering Information Kings Worthy Court, Winchester Hampshire SO23 7QA Tel: (01962) 848647 Fax: (01962) 886109 e-mail:
[email protected] website: www.itc.org.uk The Digital Television Group Liss Mill, Liss Hampshire GU33 7BD Tel: (01730) 893144 Fax: (01730) 895460 website: www.dtg.org.uk
Maxview Limited Common Lane, Setchey, Kings Lynn Norfolk PE33 0AT, England Customer Helpline Tel: (01553) 811000 Fax: (01553) 813301 e-mail:
[email protected] website: www.maxview.ltd.uk
Channel 5 Broadcasting Limited 22 Long Acre, London WC2E 9LY Tel: (020) 7 550 5555 Fax: (020) 7 550 5554 website: www.channel5.co.uk ONdigital 346 Queens Town Road London SE8 4DG Tel: (020) 7 819 8000 Fax: (020) 7 819 8100 website: www.ondigital.co.uk
Eutelsat Helpdesk PO Box 846, Bristol BS99 5HR Tel: (0117) 954 9191 Fax: (0117) 925 3525 website: www.eutelsat.org British Sky Broadcasting Grant Way, Isleworth Middlesex TW7 5QD Tel: (020) 7 705 3000 Fax: (020) 7 705 3030 website: www.sky.co.uk Confederation of Aerial Industries Fulton House Business Centre Fulton Road, Wembley Park Middlesex HA9 0AF Tel: (020) 8 902 8998 Fax: (020) 8 903 8719 e-mail:
[email protected] website: www.cai.org.uk The Radio Authority Holbrook House 14 Great Queen Street, Holburn London WC2B 5DG Tel: (020) 7 430 2724 Fax: (020) 7 405 7062 website: www.radioauthority.org.uk Arboricultural Advisory and Information Service Alice Holt Lodge, Wrecclesham Nr Farnham, Surrey GU10 4LH Tel: (01420) 22022 Fax: (01420) 22000 website: www.treeadviceservice.org.uk Astra Marketing Limited The Progression Centre 42 Mark Road, Hemel Hempstead Hertfordshire HP2 7DW Tel: (01442) 235540 Fax: (01442) 235517 website: www.astra.lu
LFTVGUIDE Iss4
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