TV-Link type remote control extenders connect to the UHF co-ax cable feeding a secondary TV in, say, the bedroom from a Sky Digibox in the living room to send remote control signals back to the Digibox so you can change channels, pause a recording & so on. They can sometimes suffer from interference from the TV or ‘ground loops’ that prevent the remote control commands getting through.

The simplest way around this problem is to move the whole TV-link unit away from the TV. Simply make up a lead of the right length (up to 3m for some TV‘s) using decent co-ax & male & female UHF connectors. It is a good idea to use all TV-Links with a short fly lead even if there is no interference problem, as this reduces the strain on the TV‘s aerial socket.

If you find that the remote control commands don‘t get through to the Digibox when the TV-Link unit is connected to the TV but do when the connection is broken, you may be able to get both Digibox output on the secondary TV & remote control of the Digibox by using a ‘decoupled’ lead between the TV-Link & the secondary TV set.

To do this you will need a length of co-ax cable then make two cuts about 0.5cm apart through the outer sheath all around the cable (not too near the cable ends). The easiest way to do this is hold a sharp knife against the sheath at 90 degrees to the cable & twist the cable around. Cut all the way through the outer sheath but not too much farther. Now remove the sheath between the cuts to reveal the copper braid beneath & carefully remove the exposed braid & the copper foil beneath that, so now you have the inner insulation (which contains the central conducting wire) showing all the way around the cable.

Wrap some clear sticky tape around the cable extending about 2cm to each side of the exposed section. Make sure that the tape is stuck well to the outer sheath on each side & to the central insulation in the middle. Now wrap a strip of aluminium cooking foil around the cable so it covers the sticky tape. Secure the aluminium foil in place & protect it by wrapping some insulating tape around the cable, again extending the cover to each side of the foil. For a better, more permanent job use self-amalgamating tape (as used to waterproof LNB cable joints outside) instead.

The decoupled cable now has a connection between the plugs at each end on the central conductor but the connection on the shield is broken. This prevents any DC connection but doesn‘t stop the UHF signals getting through. Don‘t decouple the cable from the Digibox to the TV-Link (or the TV-Link will not get power & so will not work); only use a decoupled lead between the TV-Link & the secondary TV - & it could restore your control of the TV in the bedroom.

Just about every digital satellite or terrestrial receiver available can display onscreen the received signal strength & signal quality to help set up the antenna or diagnose a fault. The display is usually in the form of a bar graph, often with a percentage value given. There‘s much confusion as to what these readings mean & even if they matter.

Signal strength is the easiest to understand. Signal strength is simply an indication of how much signal there is. It‘s rarely presented onscreen in any meaningful fashion so you don‘t know the actual value of the signal level. What‘s more, presentation as a percentage is plainly meaningless - while it‘s clear that 0 per cent signal strength is not good, what is 100 per cent of an open-ended quality?

Signal strength tells you if your receiver is connected to an aerial or satellite dish that is pointed at a transmitter or satellite. It doesn‘t tell you that you are receiving the right signal but it has the overwhelming advantage of being very quick to respond, so when you‘re hunting for a satellite or TV transmitter, the signal strength display gives instant feedback.

Signal quality is a different idea. This is not concerned with the signal itself but the digital content it is carrying. The digital data stream arriving at your antenna is made up of packets of digital bits & the whole stream modulated on an analogue radio signal. Any hiccup in the signal path or the reception system or interference picked up along the way can corrupt one or more bits which, as it‘s digital TV, could throw the whole picture. So along with the useful data bits in each packet of data, extra data bits that are used to check & correct the whole packets are also transmitted. When regenerating the original data the receiver calculates the proportion that were corrupted, or in error. This value is called the bits error rate (BER) & in a normal signal it is a tiny fraction - one bit in every thousand, or less.

Subtracting this bit error ratio from one gives a measure of the proportion of ‘good’ bits in the data stream & this is essentially what the signal quality is showing. Signal quality gives a true indication of the ability of the received signal to make a watchable picture but it‘s not an instantaneous measure so it‘s less useful for the initial alignment of an antenna (but great for the fine tuning).

Also, the displayed signal quality is not usually a direct translation from the BER, as that would put the whole range (from picture to perfect picture) up at the top of the bar graph, so the area of interest is expanded to be easily seen & assessed. How the expansion is handled varies between different receivers, so even this more scientific value can‘t be relied on as an absolute measure of the antenna‘s performance.

If you are upgrading to Sky HD with a system including an older high-definition TV you may have problems connecting the receiver to the TV. The first HD television sets did not have HDMI inputs (the new digital connection standard was not commonly included on domestic screens).

Any television bought in 2005 or earlier could prove problematic & for a couple of years after that a few models were sold without the HDMI socket essential to be truly HD-ready.

TVs with a digital DVI input (as used on computer monitors) can be simply connected with an adapter or converter cable. The DVI input does not accommodate audio & so that has to be separately routed from the digibox‘s digital audio output (or even the analogue stereo outputs).

Some older HD TVs have no digital inputs at all - they are equipped only with YPbPr component video inputs to feed a high-definition signal.

The first production run of Sky HD receivers had component video outputs, especially to cater for viewers who had older HD TVs without HDMI.

While connecting the digibox & TV screen via component video is not as convenient as HDMI (again, there is no provision for audio within the component video connections so that must be linked separately), the picture quality possible is close to the HDMI connection even though the signal is converted from digital reception to analogue YPbPr & then back to digital for display on screen.

Sky+ HD boxes do not have the component video outputs - primarily because these do not provide the content protection (HDCP) available on HDMI.

There are units available to convert the signal from HDMI to component video but these typically cost more than 200€.

You may well find that your TV is not really up to providing the best picture from Sky HD anyway. Such older sets tend not to have a standard HD native resolution (as the display panels were usually designed for computer use). & so the 720p or 1080i signal from the digibox has to be asymmetrically scaled to fit the screen.

Moreover, such a TV is six or more years old & probably due for replacement soon anyway. The quality of HD TVs have improved considerably in this time & the prices have plummeted.

So before you invest in signal conversion equipment, take a look at the HD LDC screens of the same size (or bigger) available now - you may be pleasantly surprised by the price & certainly will be by the picture.

If you are upgrading to high definition & really must keep your old pre-HDMI TV, then try out Sky HD using a Thompson HD box (with component video outputs) bought second-hand- but be sure that you get one with a replaced/repaired power supply if you want it to last.

Most TV satellites occupy a geostationary orbit at a height of about 35,700km above the Earth‘s surface (or 42,200km from the centre of the Earth).

The higher the orbit, the faster the satellite is travelling but the longer it takes to make one complete orbit of the Earth. In an orbit at 35,700km, a satellite takes 24 hours to go once around the earth & so, if it‘s orbiting directly above the earth‘s Equator & in the right direction (west to east), the satellite keeps step with the Earth rotating beneath it & to an observer on the ground it appears to stay in one place in the heavens while the stars rotate behind it.

The satellite only appears perfectly stationary if it orbits exactly over the equator but, in reality, the earth is not a uniform sphere & there are other bodies (in particular, the Moon & Sun) that influence the satellite‘s orbit with their gravitational pull & its orbit will slowly become eccentric (more elliptical) so it moves orbital position & inclined (tilted away from the equatorial plane) so it travels slightly north of the equator for half of the orbit & south for the other half.

To counteract this effect requires constant adjustment using on-board motors to nudge the satellite back on track (called station keeping).

If a satellite‘s orbit is not adjusted in this way, the incline of its orbit will gradually increase & from the ground, the satellite appears to move up & down in a figure-of-eight pattern through the day.

This movement prevents its use with fixed dishes & so the incline of a TV satellite is kept small enough so the satellite remains within an imaginary box about 150km wide & it appears stationary.

However, as a satellite approaches the end of its life, when the supply of on-board fuel for the station keeping motors is getting low it can be allowed to develop a sizable incline to its orbit, by operating the station keeping motors less often.

Although this makes the satellite unsuitable for direct-to-home broadcasts (as it cannot be used with fixed dishes) it can still function for occasional use such as outside broadcast links when the dish is especially aligned on the satellite anyway.

Less station keeping means less fuel is used & so being in inclined orbit can extend the satellite‘s life by many years. Home dishes can be fitted with a motor to vary the elevation of the dish to track the daily movement of an inclined orbit satellite.

The 80-odd TV channels that a Freesat box produces are only a fraction of what‘s available by satellite without paying a subscription. You don‘t have to add anything to your system to access more free-to-air channels broadcasting from Astra & Eurobird 1 at 28E; you simply switch your receiver to non-Freesat mode & tune in the other channels using the frequency, polarity & symbol rate information listed in channel Check & accessing these channels must be done through the non-Freesat mode channel list too.

However, if your TV interests range father field you will want to access channels broadcasting from other satellite positions, such as Astra 19.2E & Hotbird at 13E. Here, you will not only find foreign language channels but even some FTA channels only available encrypted from 28E, of course, for this you will need to replace or update your dish setup & also switch your receiver between the new satellite position(s) & the basic Freesat offerings from 28E.

With a receiver such as Humax‘s Foxsat HDR or Technisat‘s HDFS you have an enthusiast‘s receiver & a Freesat receiver in one & you can connect a DiSEqC 1.2 or USALS motorised dish or a multi-feed dish & DiSEqC switch to transparently select between satellite positions in non-Freesat mode. (With a twin-tuner Freesat+ machine, it‘s a good idea to use a duel LNB on 28E with the receiver‘s LNB2 input permanently connected to one output & LNB1 connected to the second output & the other LNBs via the DiSEqC switch).

However, run-of-the-mill Freesat receivers have no hardware or software to cope with switching between satellite positions. Although there are some stand-alone DiSEqC drivers available that could be used to operate a DiSEqC switch or motor independently of the receiver, these are mostly incorporated into signal meters & designed as installation aids.

You can resort to disconnecting & connecting the LNB cables to switch to another satellite but this can damage the receiver‘s connector in time. So, if you must go this route you should use a short lead from the receiver with a female F-connector on the end to make & break the connections. Better still, use a manually operated LNB switch, or A/B switch - although these usually have only two inputs so you are restricted to Astra 28E & just one other satellite position. Although an A/B switch suitable for satellite signals need not cost much (they‘re available for under 10€), don‘t be tempted to use a very cheap one made for aerial connections only, as this will introduce losses & noise to a satellite LNB feed.

To tune in a channel on the 2nd satellite, select the non-Freesat mode, select the transponder or satellite scan, switch to the non-Freesat satellite & start the scan. To view a non-Freesat channel try to switch to the non-Freesat satellite as quickly as possible after selecting the channel from the non-Freesat mode & also be quick about the switch back to the Freesat LNB. But, sadly, whether you swap the cables or use an A/B switch you will still have to get up from your armchair to change satellites.

It could be a problem with the LNB or the fault could be with the cables or connectors. Your investigation would seem to rule out the Sky+ receiver. Assuming that you hadn‘t disturbed the connections at the back of the receiver before the fault first appeared, it‘s unlikely that it‘s a problem with the connections inside the home. But these are easy to get at so it‘s worth checking that the F-connectors on the end of the faulty LNB feed (the one last connected to input 1) are still firmly in place & that the central wire inside the mouth of the connector has not been bent over.

Next, take a look at the connectors on the other end of the cable, at the dish. Check for external signs of disconnection - is the waterproofing (tape or boot cover) intact - & that there‘s no sign of damage to the cable. If it is the LNB at fault then, as it is a quad LNB you can try using one of the ‘spare’ outputs instead of the failed one. Don‘t disconnect or connect any cables at the dish while the receiver is plugged in & switched on.

If you can work out which connection at the dish corresponds to the faulty feed cable inside your home, disconnect this from the LNB output & move it to one of the spare outputs (can‘t tell which is which? Just pick one & see if it removes the signal from the correctly operating feed; if it does you have the wrong one!) Check to see if you now get a suitable signal strength & quality reading from both inputs of the Sky receiver.

When you have both LNB feeds working correctly, make sure that all four LNB outputs (the connected ones & the spares) are properly waterproofed.

If neither of the spare outputs produce a signal on the problem feed cable, then your LNB may be ¾ faulty, or it‘s the cable. Try each of the two cables in turn connected to the one LNB output that you know works & see if the corresponding other end produces a signal reading on the Sky+. If one cable fails to transmit the signal, then it is faulty & you should replace that cable - or even both of them for good measure. If both cables are working well but you can‘t get two feeds from the LNB, you will need to replace the LNB.

The first tip for anyone considering bowing to the other half’s insistence that a stack of AV gear - all piano-black & florescent displays - is somehow not attractive or suitable for the living room & should be in a nearby cupboard or (far worse) a TV cabinet is don’t.

Basically, your AV gear is meant to inhabit the same fresh air as you & your TV do & there are innate problems with shutting it all away. It’s mainly down to ventilation. Every satellite or terrestrial receiver, PVR, DVD recorder or AV amplifier needs a supply of fresh air to keep its electronics cool. All such equipment has slots in the case to allow cool air in & warm air out & some have fans built in to increase the air flow. If the ventilation slots are blocked or the air supply is restricted, you stand the risk of the equipment overheating & at best, failing or even, at worst, catching fire.

The solution is to make sure that the equipment has room all around it for air to circulate & is not stacked up too high (so each item ‘cooks’ the one above). The cupboard or cabinet should have plenty of ventilation itself. Fit ventilation grills (around the back if possible) & if necessary, you should fit a fan to the cupboard to increase the air circulation to all the equipment. Small, cheap & almost silent fans are easily available (for computer cooling) & can be run from a small (old) gv or 12V mains adapter, ideally, fit a couple to the cabinet to force air through the cabinet bottom to top.

Another problem with equipment in cabinets & cupboards is that when hidden from sight, the equipment is also hidden from the infrared reach of remote controls. Again, the answer is quite simple - install a remote control extender such as the Global TV-Link (for use with a Sky dig box) or a TV-Link Plus (which can also be used for other equipment too).

The ‘magic eye’ IR receiver can be placed discreetly outside the cabinet, close to the TV screen & then the IR emitter (for a TV-Link plus type system) placed inside the cabinet in front of the Av gear. The system can be powered by the ‘RF2’ on your Sky receiver, if you have one, or by a small mains adapter if you don’t.

If you are already using the second RF output from the Sky box to feed a secondary TV elsewhere, then a simple two-way (TV-Link-compatible) distribution amplifier (or even a DC-passing splitter if the cable run to the other television is very short) will allow the in-cabinet extender to be connected.

Just one IR emitter will often operate all the equipment in the cabinet (because it’s close together & the enclosure reflects the IR signals all around the various AV boxes).

Fortuitously, because the equipment is shut away from outside interference from sunlight, fluorescent lights & even the television screen, remote control of equipment inside the cabinet can end up (as long as it’s ventilated) being more reliable than when it is outside in the living room.

These days all AV equipment that requires manual operation in daily use, such as TV sets, satellite & DTT receivers, DVD players & audio systems, uses a remote control. Indeed, most such devises can only be fully managed from the handset. The proliferation & dependence on remote controls has changed the way we watch TV, lessening our attention span, demanding more tailored programming & is at least indirectly responsible for the introduction of onscreen logos & trailers run over programme end credits.

Basically, remote control is simple, digital data is sent from the handset to the equipment. The carrier medium must be cheap & easy to produce & detect but not naturally detectable by people, or the control operation will interfere with enjoyment of the TV or audio. Most AV remote controls use infrared light to carry the information. Some other applications (garage doors & cars, for example) use radio & a few devices (including early TV remote controls) use ultrasonic sound. Infrared light is of a lower frequency than ‘normal’ light & not visible to humans (although it is detectable by some animals & most digital cameras).

A remote control handset contains infrared LEDs to produce the infrared light beam & the AV equipment has a photodiode sensitive to infrared to pick up the commands. Because there is a lot of infrared light naturally around us, the beam from the handset is ‘modulated’ (switched on & off at a high frequency) so it can be distinguished from infrared ‘noise’ from other sources, the equipment ignores all infrared light that is not blinking at this frequency (although some energy-saving bulbs flicker at a similar frequency, confusing AV devices). The modulation frequency used varies between devices & manufacturers but is usually 30kHz-55kHz.

The information to be sent is encoded in the modulated signal by pulsing that signal on & off. Different manufacturers use different protocols for this encoding & different interpretation of the data sent. With most control protocols (but by no means all) the distance between the pulses determines whether it is a data 1 or 0 bit, so a chain of pulses sends a stream of data bits. Each time you press the handset button a short ‘header’ sequence of pulses is sent, followed by a stream of data (usually an address followed by the command) & then extra data or a repeat of the data, or an inverted repeat of the data (for error correction). The whole command takes only a fraction of a second & is repeated until you release the button.

It’s a complex process but integration of most of the functions onto single chips for both the handset & the equipment means that implementing remote control on any equipment is simple & cheap & so it’s now universal.

When your channels vanish, the LNB soon comes under suspicion but it’s hard to tell if it’s actually gone wrong. Although LNB’s don’t normally fail for no reason, the constant heating during the day & cooling at night can crack internal connections & any water inside can corrode components or the circuit board. Static electricity strikes can also burn out the LNB, which doesn’t always affect all of the ports.

The only sure way to test an LNB is to fit it to a dish, cable & receiver, all known to be working & then to check that every channel is received as expected (and even this continues through a few days’ cycles of hot & cold) That’s not often practical, so the professional usually carry a range of replacement LNB’s to simply substitute for a suspect unit. However, when you’re trying to diagnose a problem with your home system you probably won’t have a test antenna & substitution means the expense, time & bother of buying another LNB. So can you test the existing LNB with simple equipment? You should check if the LNB is drawing any current & you can do this without even going outside. Connect a multimeter - set to read current - into the LNB circuit. Disconnect the LNB cable from the receiver, connect the sleeve of the F-socket (the screw thread) to the collar of the F-plug with a short lead with crocodile clips or similar & with one probe from the meter inserted into the central hole in the F-socket, carefully touch the other to the central wire in the F-plug (be careful not to short the wire to the collar). It’s fiddly but it will give you a reading of the current taken by the LNB. Ideally, this should be compared with the manufacturer’s specification but if that’s unknown you can reckon on a minimum of about 6omA (although twin/quad output models will draw much more)

If the LNB is drawing less than 5omA (especially if it’s drawing none) it’s probably not functioning at all but you should check the connections at the other end & check the cable’s not broken by reconnecting the receiver & measure the voltage between the central wire & the collar of the LNB connector - it should be at least 12V.

You will need to install a lot of coaxial cable if you are planning a new distribution system for sending AV signals around the home.

Using the right cable is, of course, vital, it’s best to use double-shielded satellite co-ax throughout your system, whether the cable is to carry a UHF or aerial signal, or the IF signals from an LNB or smart switch.

The double shielding means that around the central core & dielectric there is both a metal foil & a metal braid, providing superior interference shielding to the cable than the single braid found in cheaper UHF cable. You should also use the very best double-shielded cable you can afford to keep cable losses to a minimum.

If the cable’s going outside, then it should be made for the job, with an outer sheath made to cope with the UV light from the sun that it will be exposed to. Otherwise, it will soon degrade & crack, allowing water into the cable corroding the metal shield & core.

Pick the route carefully so the cables are not prone to knocks & snags from passers-by & are hidden from sight as much as possible.

Inside, cables require less defence from the elements but still need protection from bumps & knocks so the route is still crucial. Wherever possible, cables should be hidden behind plaster or under floorboards, but at the same time you should try to keep signal cables away from mains wiring, to avoid interference. Removing floor coverings, lifting floorboards & chasing channels into walls is a major & sometimes destructive job so it’s not always practical. However, cables should never be simply laid under a carpet or rug, or across a doorway. If they must go above the floor, run them around the edges of the room, along the top of the skirting board & around architraves to keep them out of the way of feet, furniture & vacuum cleaners.

Key to keeping your installed cables at the same performance as in the shop is to make sure that all curves & bends are kept as wide as possible. If a cable is bent with a radius of less than about 10 times its diameter it will become too kinked inside & its transmission will be seriously affected. The same problems can occur if you stretch a cable when pulling it through a cleverly hidden but tortuous route, or clip it in place with the wrong size or shape clip. Treat your cable with loving care when it’s being installed & it will repay you with years of trouble-free use.

In many ways, installing & aligning an indoor or ‘set-top’ aerial for digital terrestrial TV is harder than an external unit, or even a loft aerial. Although an aerial in your living room has no access issues, the fact that they are inside a living space presents all sorts of problems in itself.

The first piece of advice for set-top aerial installation is ‘don’t do it!’ Although the obstacles of attaching an aerial to you chimney or gable wall, or the risks of wallowing in loft insulation & putting a foot through the ceiling appear high (& they are), the rewards to picture quality of a proper aerial in a proper position more often than not outweigh them. Only when you are close to the transmitter & preferably situated high above or far from the interference-generating traffic on the street, can a set-top aerial really do justice to the digital broadcasts & should only be considered for a temporary arrangement or if an external aerial is impossible (not just inconvenient). Even then, go for a big one & the sort that looks like a small external aerial (not loops of wire) usually work best. Don’t be fooled by on-board amplifiers - these rarely contribute much as it’s the raw signal gathering abilities that really counts.

Positioning & aligning a set-top aerial is often fraught with difficulty. In the living room the aerial is likely to be bombarded by signals - direct & reflected - from all directions, so a tiny movement can make all the difference between a strong signal & next to nothing. What’s more, once you have found the hotspot, something as simple as shutting the room door, closing the curtains or even other people in the room can render your reception unwatchable. The reflections off surfaces in the room & the transmission of the broadcast signals through objects can be dependent on frequency, so try to get the set-top aerial as high as possible. Of course, it doesn’t have to go on top of the TV at all - a nearby cupboard or wardrobe is often a good spot (if the cable isn’t long enough buy a decent quality extension). Watching the signal strength display, move the aerial around & point it every which way in search of a decent signal. When it comes to reception with a set-top aerial nothing is too stupid to try. If you get the best signal with the aerial pointed up the chimney, so be it.

Fine-tune the alignment carefully & check that you have got the best position & aim for all the multiplexes that you should (or can) receive. The chances are that you won’t get perfect reception for them all & you may have to learn to live either with some channels missing or with a well-rehearsed move of the aerial when you change channels.

I have a Technomate receiver that does sterling service as far as channel reception is concerned but I would like to know what’s on more in advance of the now and next information that I can see?

It is not the channels that differ, all the Sky and Freesat channels transmit the information for seven days of programme information, along with various flags and series data - but the receiver you use. Skys channels transmit the data suitable for Skys EPG, the Freesat channels transmit data for the Freesat EPG and those channels in both packages transmit both.

However, the EPG software is different and proprietary to Sky and to Freesat, so receivers that are not authorised by either service (such as your Technomate) cannot use the data and can only show the (third set of) data transmitted, the standard now-&-then information demanded for DVB compatibility (which all channels have).

There is also a DVB seven-day EPG standard and your receiver will be able to display this. However, it is not compulsory for channels to transmit the information (it’s only compulsory to transmit the now-&-then data) and no UK channels use a seven-day DVB EPG. (In fact, very few channels at all do, it’s mostly only the German channels that make use of this DVB feature).

The only solution, apart from using a PC satellite tuner and software to extract the EPG information, is to use a Sky receiver or a Freesat receiver to watch these channels and take advantage of the EPG these boxes contain.

It sounds like you have your main TV connected via HDMI (or maybe component video - hopefully not scart!) So first the simplest explanation - have you plugged the cable to the bedroom into the right socket - the secondary UHF output (labelled RF - out 2)? The primary output does not provide the 9V to power the TV link remote eye. Have you also switched on the 9V power output? Again, without this the control from the bedroom is not possible, although the TV there will receive the picture and sound.

You can tell if the 9V power is getting through if the LED provided on most types of remote eye is on. If it isn’t, press Services - 0 - 0 - 1 - Select - 4 and switch the RF Outlet Power Supply to On.

Another possibility is that the DC connection for the 9V power has broken somewhere along the co-ax from the Digibox to second TV (this won’t necessarily affect the picture and sound ‘getting through’).

Given that you have just changed Digibox, this is most likely to have happened in the co-ax connector plugged into the Sky+HD and you can try jiggling the plug in the socket and/or check the connections inside the plug (have the plug soldered onto the cable for the best long-term solution).

A few makes of remote eye do not work with all types of Sky Digibox and it may be that yours will work with a Sky+ but not a Sky+HD box. Or it may be just that your TV Link system has failed, coincidentally as your Digibox was replaced. The only way to be sure of this cause is to temporarily replace the remote eye with another one and see if that works.

When you upgrade from a single-tuner receiver to a dual-tuner PVR a second LNB feed is required for the second tuner. Of course, it is always best to simply run another cable from the dish to the new receiver (and maybe to replace the old single cable as well) but this is not always possible. The location of the dish or receiver can be a problem, there may be a proscription on cables on the outside of the building or even simply that the interior decor has just been completed. However, there are ways around the problem. Sometimes, when the original cable has been installed with forethought it can be replaced without disturbing the structure of the building around it. If the cable runs through a wall cavity or through a conduit under the plaster as it comes down the side of a building it can be possible to use the existing cable to pull through a new cable, provided that no sharp bends lie in the path and the whole passage is relatively free. While that may not appear to help matters as the holes in walls and conduit provided will probably not be large enough to accommodate two cables - it can still provide the solution. If the replacement cable used is so-called ‘shotgun’ double cable this will provide two independent connections in little more space than the single standard cable. Shotgun cable uses two thin co-ax cables joined together in a figure-of-eight arrangement and can often be attached at one end of the existing cable and both fed and pulled (gently) through the same route.

The only downside is that shotgun cable is a higher impendence than standard co-ax and so it cannot usually be used for runs of more than about 20m. It also requires special F-connectors to suit its size. Where there is no possibility of pulling a new shotgun cable through to replace the original cable you can simply send both signals down the same cable with a clever pair of devices - a stacker and destacker. The stacker at the dish combines the two LNB outputs onto one cable, moving the frequencies of one LNB above the other and the destacker at the receiver reverses the process producing two LNB signals, but only one cable connects the two units. Very cleverly, the stacker also transmits the two independent supply voltage and 22kHz command signals to the destacker for each LNB, so the receiver ‘sees’ two separate normal LNB feeds. A stacker-destacker system gives only a small loss in signal strength but as the single co-ax cable is carrying twice the bandwidth it is designed for, the system will probably not work if your cable is old, very long, not the best quality to start with, bent or kinked or has poor joints or wall plates.

Heat is a satellite receiver’s worst enemy - or, at least one of them. When you stack up the AV gear beneath the TV or, even worse, inside a cabinet, the heat generated by the electronics inside cannot get out of the receiver. As the temperature of the electronics rises, so it starts to do a strange thing - from simply not working through corrupting the picture, to changing channels by itself.

The problem can affect all receivers - especially if they have been modified with extra electronics, such as hard disc drives added inside - but can sometimes be solved by fitting a fan to the receiver. You may be able to sort out the problem without adding a fan - move the receiver from the cabinet, or the AV stack, or simply ’give it room to breath’. Never put a receiver on a carpet as this can completely block ventilation holes underneath - and you can test whether a fan is likely to solve the problem by directing a normal household fan at the receiver. If the fault does not then occur over a long period with the fan blowing (relatively) cool air over and into the receiver, then a fitted miniature fan may well sort out the problem in a more elegant fashion, for just a few pounds outlay.

The fans are about 60mm square (there’s probably at least one in your PC) and can be mounted in the casing of the receiver (although that requires cutting a hole in the box). Stuck to the outside with double-sided foam strips over existing ventilation holes, or even mounded inside to blow air over the critical overheating components.

The fan can be used to blow air into the receiver or suck it out. A fan must be installed to ‘work with’ any existing fan (that is working properly, but not cooling the electronics sufficiently) and not fight it.

Suitable fans are made for PC applications and usually run off a 12V DC supply. A suitable supply is probably available from the receiver’s power supply (the fan draws a microscopic current) but 9V or even less will usually work.

If the fan is too noisy you can fit resistors in series with the fan’s power supply to make it quieter (& also extent its life) but it’s better to avoid this as the resistor (marginally) adds to the heat generated inside the receiver and it slows the fan down, so reducing the flow of cooling air to the overheated electronics that are causing the problem in the first place.

Freeview is established in the UK as the ‘free option’ and is transmitted from local masts and received via a digital aerial but is not available in Spain. Spain have their own similar system called TDT, depending on where you are, there are as many as 34 channels available. Some of these channels are in English or have the facility to change the audio setting back to English if the programme/film was originally made in America/UK

When most people think of satellite TV they automatically think of Sky but now you have a ‘free option’ via satellite called Freesat. This service is broadcast direct from the Astra 2 group of satellites in a geostationary orbit at 28.2 SSE and to receive this service all you need is a dish and a digital receive, the size of the dish required will depend on the signal strength in your area.

Freesat was set up to ensure that everyone can access the best of digital satellite TV, for free, no mater where they live, the company is owned by two of the most popular broadcasters, the BBC and ITV with over 140 great digital TV and radio channels. Favourites such as BBC1, ITV 1/2/3 Channel 4, More 4, Film 4, basically all the usual British terrestrial programmes with no contract or monthly payments, plus up to 70 hours a week of HD from the BBC and ITV at no extra cost.

At this present time the signal for Channel 5 Freesat is on a very weak transponder and only works for a short period in the daytime but you can receive this channel plus Five Life and Five US with a Sky digital receiver and a Free to View card.

In your area I would recommend a Famaval Portuguese 2.4m dish for the British TV and a Televes high gain aerial for the Spanish, this can be set-up using an integrated reception system (IRS) which requires a Quattro Invacom LNB on the satellite dish that produces all four sub bands (polarities) separately i.e. vertical low, vertical high, horizontal low and horizontal high (unlike a standard invacom quad LNB which will only allow four individual feeds). This will then feed a multi-switch which has the four satellite cable feeds from the Quattro LNB and also a cable from the UHF aerial signal, when this is added to the multi-switch the signals can then be accessed by any of the ports on the multi-switch, this is then send via a cable to a TV/SAT combiner or a diplex plate to separate them back to individual signals for your satellite receiver and built-in digital tuner of your TV or separate terrestrial digital receiver. You could also use an eight output multi-switch which would allow each property to have two feeds but we would suggest that you go for a sixteen output switch which would feed four cables to each property so that you have the capacity to use a twin tuner, (PVR) personal video recorder plus two extra feeds to other rooms.

In each room that a feed is required you will need a TV/SAT combiner or a diplex type wall plate with two sockets, one for satellite and one for terrestrial or a three socket plate if using a PVR.

It will then be necessary to have individual digital receivers in each location allowing you to watch different channels in each room, these will usually be either a standard Sky box, Sky+, Sky+HD, Freesat, Freesat HDR or other generic receivers which can be connected directly to the wall plate in each location. Free to air receivers can only pick up TV channels that are not scrambled and there are thousands of these out there. Common interface receivers can be up-graded to receive scrambled channels if you find you want a particular foreign TV service. Conditional Access receivers have extra hardware that allows you to insert an official viewing card for scrambled subscription TV channels i.e. Sky, Showtime, Sky Italia

What happens is that, before the receiver leaves the factory it is loaded with software, this software is mainly its operating system but in addition it also includes a set of frequency data that the manufacturer has prepared for you. This data is collected from the satellite provider and other reliable sources and is usually accurate at the time it is prepared. However, satellites are constantly changing, channels move, sometimes change frequencies, disappear, new channels appear etc and so the frequency data is changing all the time. To correct this problem manufacturers release new software on a regular basis, this new software may well include improvement in the operating system such as fixes for ‘bugs’ or errors in the operating system (digital receivers are exactly the same as a computer, they are driven by software and no software ever released is perfect as it is written by humans and humans make mistakes) The operating system in a receiver is constantly being fine tuned and improved, also embedded in the software will be the latest set of ‘channel data’. On some receivers upgrading the software can be done ‘over the air’ via the satellite Astra 2 for Sky and Freesat, other receivers have to be upgraded by picking up the software from the manufacturers website and using a RS323 lead. Channel data can also be scanned in by adding any new frequencies, to scan in a digital channel frequency the polarity, symbol rate and FEC must be entered into your receivers ‘install’ menu system, this is called scanning a channel (or to be exact, scanning a transponder) manually. Digital channels are compressed and when one transponder is scanned from one set of frequency data, up to 10 channels can appear from the one scan. All receivers will allow you to enter frequencies manually one at a time but they can also offer an automatic scan, that means, by simply selecting the satellite you require from the menu and going to auto scan the whole frequency range will be scanned in.

Dish size is very important to receive every channel available, small dishes can be used but as some channels are more powerful than others, the small dish will only work on a percentage of channels but not all of them (many Sky/Freesat channels can be received with a small dish). The BBC is the weakest channel and so unless the dish is big enough to receive every channel this will not be available.

In addition, it is important to note that there are 2 beams aimed at Spain, the north and south beam. The BBC and ITV are not on the south beam but many other channels are. The south beam can be received anywhere in Spain on an 80cm dish, as far as the north beam is concerned, the dish sizes required can be up to 2.4 or 3.1mts depending on the area.

HD of course stands for High Definition which delivers 4 times as much clarity as a standard definition picture making it a lot sharper and clear.

If you have a 1.9m or 2.4m dish this will be more than adequate to pick up the extra HD channels. A Sky+ HD or Freeview box will require an LNB with multiple outputs to provide the two separate feeds needed to watch one channel and record another. As you already have Sky+, you should already have the two feeds needed.

If you want to watch the Free to view HD channels which are BBC HD, Channel 4 HD, Luxe TV HD and ITV HD you will need an HD box and an HDMI compatible TV, the HD box can run on a standard definition TV but you will not be seeing HD TV. You will need to add ITV HD manually to other channels and the settings are 11427 H 27.5 2/3. For instruction on how to do this go to our website, click on Digital TV, then click on Transponders to access this information. If you have a full Sky subscription you will pick up over 35 HD channels, more than any other provider and the service supports two HD formats, 1080i and 720p, via a standard HDMI socket. You will need to up-grade your subscription with Sky as there is an extra charge for these channels, you can visit our website and click on the Sky logo to find out more about the channels and the charges.

• I have listed here the answers to some of the more common on Screen Messages from Sky
• Call To Upgrade Your Subscription
• This message usually means that you have missed a payment. This often occurs when a credit card has expired or been cancelled or if there were insufficient funds when Sky applied for payment. You will need to contact your supplier with a valid credit card and also payment details for your future monthly subs. This message also sometimes comes up if the receiver has been unplugged or without a signal for a long time (usually 2 weeks or more). In this case the supplier will have to contact Sky to re-send signals to your receiver.
• Please Insert Card
• Ensure card is inserted fully with the gold chip facing downwards in the correct slot marked 'sky viewing card'.
• Card Not Authorised. Please Call Your Broadcaster For Assistance
• Contact the supplier of the card about this message.
• Searching For Listings
• Unplug the Digibox from the mains electrical supply, leave it for 5 minutes then connect it back up and follow the instructions on our website under frequencies.
• There Is A Problem With Your Viewing Card
• Take card out of box and wipe with a dry cloth and then place it back in the box. Unplug the Digibox from the mains electrical supply, leave for 5 minutes and then connect it back up and follow the instructions on our website. If the message still appears contact the supplier of your card.
• This is the wrong card for the set top box
• Each Sky card is 'paired' to an individual digibox. When an active card is taken from one digibox and inserted in another it has to be 'paired' to allow access to all channels. If you don't have the correct satellite box for the card then please contact the supplier of your card.
• The Sky+ system fault
• This is something that can be easily fixed. However you will lose all of your recordings! To resolve this simply do the following: -
  1. Press SERVICES on your remote
  2. Select option 4
  3. Press 0
  4. Press 1
  5. Press Select
  6. You should now see the engineer's menu - Choose option 8, "Full System Reset"
  7. The box will now take a few minutes to reset itself.
• No Satellite Signal Is Being Received
• This message is very common during bad weather and you will probably just have to wait for the bad weather to pass. If the weather is not bad then there could be a problem with your equipment, the dish might need to be realigned, it could be a fault with the LNB or the receiver or you might need a larger dish. Before calling out an engineer unplug the Skybox, leave it for 5 minutes then connect it back up and follow the instructions on our website under frequencies. If you have access to another receiver you could try it to see if it also has trouble getting a signal through the same feed.
• MY BOX KEEPS SWITCHING OFF
• If your box keeps going into standby its probably because SKY has added a new ECO setting. To switch the setting off: -
  1. Press SERVICES on your remote
  2. Select option 5
  3. Change the ON to OFF
  4. Highlight SAVE SETTINGS and press SELECT
  5. Press SKY button to go back to channels

This is often the case with larger installations because co-ax cable is at the heart of satellite TV reception all around the world. The longer the cable run, the more likely you are to experience degradation.

Crystal Clear are able to offer fibre optic cabling instead of co-ax for community installations, its not a new idea in the greater world of communications technology, but a new one for satellite TV. With fibre, the complete signal can be sent down one cable with zero interference and practically no losses over hundreds of metres.

Just as digital electrical connections use pulses of electricity down a metal cable, fibre optics relies on light pulses down a single fine fibre of glass inside a protective sheath. Electrical signals are turned into light by a laser and focused into the fibre at one end. At the other end, a detector converts the light pulses back to an electrical signal. Although light normally travels in a straight line only, the light can follow bends in the fibre because of ‘total internal reflection’ . For the light, the fibre is like a hollow pipe and it operates just like a speaking tube, or, indeed, the waveguide sections of a satellite antenna.

A fibre optic cable uses a single ‘conductor’ and is completely immune to electrical interference, you can run these alongside a mains cable for miles and there will be no interference to the signal. The fibre won’t rot or rust and inside the protective sheath its both robust and flexible. Most impressive of all is the almost complete lack of ‘losses’ . Only a tiny amount of signal is lost along the cable, in the order of 0.3db a kilometre, compared with about 0.3db a meter for normal satellite co-ax. So you can lay cable runs of hundreds of metres without even thinking about amplifications.

To be any use for the receiver by the TV, the optical signal from the LNB has to be turned back to an electrical one like those from ‘normal’ LNBs. This is done by special converter boxes that act like a virtual LNB.

Putting together an optical system is, if anything, simpler than an electrical one, having no cable losses to worry about and access to the entire received spectrum at all points. This makes it perfect for multi-home systems, especially those stretched over large buildings or many buildings. This is where it starts to pay for itself, saving on expensive copper cable, multi-switches, amplifiers, equalization stages, the higher installation costs, earthing costs and a more pricey design stage. You will find more information about fibre optics on our website.

Getting another brand of receiver may not solve the problem as this fault is not unique to Sky+. The problem lies with how the receiver recovers from a power cut. When power is restored, the receiver comes back on in standby mode and does not get the correct current time from the satellite to say that it should be recording your programme. Only when you turn the receiver back on with the remote control or the front panel button does the receiver find out the time and see if (& when) it should be recording anything. This should not be a huge problem if you do not have many power cuts in your area but certainly many areas in Spain do suffer from frequent (albeit brief) power outages.

The only way around the problem that we can think of is to fit an uninterruptible power supply (UPS) to the receiver. This has a rechargeable battery, kept constantly topped up by the mains supply, which is instantly switched in (via an inverter to provide mains voltage) if the power supply fails. A UPS won’t keep your receiver going forever - only until the batteries run flat but, as most power cuts are quite brief, this should be sufficient. UPSs are really meant for computers and while those with big batteries can cost hundreds of euros, a small one of about 300VA can be had for a lot less. This size would only keep a computer on for about 10 minutes (enough time to save everything), but your receiver consumes a fraction of the power and provided you don’t connect the TV to the UPS as well, it should keep the receiver running for several hours which will cover most power outages. A basic UPS is cheap and very worthwhile if you live in an area with unreliable power.