Freeview distribution set up

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Hi all, I am in the process of setting up a freeview system for my house, The aerial is fitted in the attic, its a "xb10a", its quite a big aerial, I bought it from A.T.V as it was the correct type for the transmitter I use. One of the things that is puzzling me is how far the main splitter needs to be from the aerial? there is a lot of contradictory info out there, some say it needs to be far away but how far is far? 2 meters? 10 meters? and others say it needs to be as close to the aerial as possible,I don't know which to believe? and I will be annoyed if it turns out to be wrong. so to avoid headache of moving cables back and forth in the attic and possible reruns I thought I would come here and ask. The cable I am using is called "Gt100" which I bought from toolstation,its pure copper and not the aluminium rubbish, and the main splitter I bought is "Vision" 6 way. I am led to believe you should avoid amplifiers boosters. I also have a signal meter "fringe" I have measured the strength from the aerial with this meter and I get 69db which I imagine is pretty strong?,the maximum the meter goes up to is 75db, I can't get the strength any higher than 69db, the aerial is positioned in the attic at the back of the house as this is where I got the highest reading which is 69db. Any help would be great, I am just trying to work out the correct way to distribute the system from the attic?, I only want to do it once and not mess around,there is plenty slack left in the cables in attic. I also know the aerial will be better outside but I don't have the correct ladders and it will look unsightly.
thanks, hope this makes sense
 
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I just live in your average 3 bedroom house, so nothing too fancy, the cables from attic go to each room, the bedrooms,lounge and garage conversion, so 5 cables in total, the longest cable run is approximately 15m which goes to the lounge, so the cabling for the system is not particularly long. If you need more clarification from me feel free to ask. I know questions like these are a bit like "how long is a piece of string"
thanks
 
ok my set up about 25-30 years old
booster 10ft from the loft ariel in the upstairs bedroom distributing to the whole house
living room feeds back to the whole house via another booster so a video playing in a video player can be seen in any tv in the house or shed in the garden with a further booster at the back off the house
still works with freeview
what you need is to boost a good signal not a week signal so iff you have a good clean signal boosting it at point off distribution is the more practical option as you choose a booster with the correct number off connections for your needs
please not you cannot backfeed so the upstairs feed is a seperated from the downstairs feed so you choose the upstairs feed or the downstairs feed via unpluging or plugging in the areiel or video lead
 
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Hi Jim, welcome to this bit of the forum.

Well done on your choice of ATV for the aerial gear. They're good guys. I like too that you've bought decent cable. If I understand correctly, your splitter is passive (no mains power) and maybe looks something like this, would that be correct? If so, the advice with all passive splitters is to locate them as close to a mid point between all the TVs as possible. IOW, long lead from the aerial to the passive splitter, then shortest possible lead lengths from the passive splitter to the TVs. This will give you the strongest signal travelling down the long line, so better able to cope with the reduction in strength. You'll then have the weaker signals (reduced by 12dB from the splitter) travelling along shorter length of cable which means they won't lose quite as much due to the cable losses.

In very rough terms, decent coax loses about 1.5dB per 10m of cable. That's the equivalent of 0.15dB per metre. Knowing this, you can then work out the total losses for the aerial system. For example, 20m from the aerial to the splitter would equal a 3dB loss. Then say 10m from the splitter to the furthest TV would be an additional 1.5dB. Add the splitter loss at 12dB and you can see that the signal level drop is 16.5dB. That means that the 69dB from the aerial drops to 52.5dB at the furthest TV in this example.

Now, if that was your system then I'd consider the signal at the TV to be too low for reliable reception.

55-65dB at the aerial socket is about what I aim for when installing. TVs will generally work with 50dB and sometimes a bit less, but it doesn't leave much contingency should something change.

The other factor to consider is that your aerial meter takes an average reading of all the muxes (channel groups). Averages being what they are, there'll be some higher-powered muxes and some lower-powered ones. That will have an impact on what signal level the TV sees as channels are changed and different muxes are used.

The advantage with passive splitting is that the margin between the signal level and the background noise stays the same. This is the signal-to-noise ratio. Even though the absolute level of the signal drops as a result of splitting, the signal and the noise level drop by the same amount, so the margin between the two is maintained.

With active (powered) splitting it adds noise to the signal which then reduces the signal to noise ratio. However, it's possible with modest amplification to overcome the losses from cable and from passive splitting elsewhere. In the example given above then, a 0-10dB variable masthead amp set to +5dB would provide a signal lift 57.5dB at the furthest TV for a small penalty in increased noise. Your splitter appears to have power pass through, so this could be something you could explore if you find that there's some picture break-up on occasions.

If this or any other reply was helpful to you, then do the decent thing and click the THANKS button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. This is the proper way to show your thanks for the time and help someone gave you.
 
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Thanks for your kind words and awesome explanation, Yes that is the very splitter I have bought, I will give this splitter a go first and put it as close in the attic as possible before the cables all go their different directions, I will then monitor each tv in turn, If I get problems with the picture or miss a lot of channels, I will try the masthead amp as suggested, I will keep you posted, thanks:), I was trying to find a more accurate signal meter. like the analyser types as I'm sure you guys use, but they are all very expensive, in the high hundreds up to a grand in price!, not a good investment for a job I am most likely only going to do once I think:LOL:.
 
Hi @jim63 ,
You're correct; the professional meters are expensive and can run in to the thousands. Fortunately they're not all mega money, but still too much really for a one-off home install job. I got a good deal on my Horizon meter when I bought it otherwise it would have cost the thick end of £400.

Did you know you've got signal metering built in to most Freeview- and Freeview HD- TVs?

It's obviously not as easy to use as a pro meter, nor as accurate, but they often have separate readings for Quality and Strength. The Quality reading is something you don't have with the Fringe meter. It's the most useful measure when installing, and it's why those of us who install professionally spends hundreds or thousands on meters which can report on- and diagnose quality issues.

TVs do tend to meter a bit on the optimistic side, and with some of the more budget-oriented brands they lack a 0-100 scale (or even a 1-10 scale), so you end up with the blunt tool of 'Poor / Good / Excellent', but with a little lateral thinking and ingenuity then they can still prove useful.


I'd also like to compliment you on providing useful information in your posts, and on your clear writing style. That has made things much easier, and it has been a pleasure to help you.

If this or any other reply was helpful to you, then do the decent thing and click the THANKS button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. This is the proper way to show your thanks for the time and help someone gave you.
 
Hi all,just an update, I got the system up and running 3 days ago, all wired and connected, I get 57db at all tv points according to my meter, I get all the channels from the transmitter I use (craigkelly) as I live in edinburgh, No problems with sound or pixelation at any of the tvs, clear picture,clear sound:). The signal strength from frequency 21-37 are all above 90% in the range of 91 to 97% and the signal quality stays at a solid 100%. However one thing that is puzzling me is frequency 55 and 56 have a very low signal strength, (according to the tv) they are only at 35% strength each, however the quality for both is still a solid 100% like the other frequencies I use 21-37, and I still get all channels from 55 and 56 without any trouble with picture or sound. What is going on here then? what is even more confusing is on another tv in the house, it says 55 and 56 signal strength is strong?, but again I get all the channels and the quality is very good.

Is this a job well done? or would you recommend I get a wideband aerial or amplifier to give the last frequencies a kick? Or should I just leave it as it is? I believe the xb10a is a group A aerial, which may explain why 55 and 56 are low, however the site I bought this aerial from seemed to recommend it for loft installs and transmitter I use which is "craigkelly".
I don't know a great deal about setting up tv or aerial systems, so expert advice and opinions is more than welcome.
cheers
Jim
 
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I did wonder if you were on Craigkelly.

Given the channel spread and loft installation, personally I'd have favoured a Log36 with the option of a 0-10dB variable masthead amp with 4 outputs. The shorter length compared to crossbeams (XB) makes loft installation a bit easier, whilst the relatively flat gain curve means that all the muxes have roughly the same gain from the aerial. IMO, the small penalty of noise from the amp is offset by the flexibility to alter the gain and from the aerial's smaller size.

The Group A XB10 will come in to its own more as the 700MHz clearance gathers pace. In a couple of years time there'll be no transmissions above ch49.


If this or any other reply was helpful to you, then do the decent thing and click the THANKS button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. This is the proper way to show your thanks for the time and help someone gave you.
 
I did wonder if you were on Craigkelly.

Given the channel spread and loft installation, personally I'd have favoured a Log36 with the option of a 0-10dB variable masthead amp with 4 outputs. The shorter length compared to crossbeams (XB) makes loft installation a bit easier, whilst the relatively flat gain curve means that all the muxes have roughly the same gain from the aerial. IMO, the small penalty of noise from the amp is offset by the flexibility to alter the gain and from the aerial's smaller size.

The Group A XB10 will come in to its own more as the 700MHz clearance gathers pace. In a couple of years time there'll be no transmissions above ch49.


If this or any other reply was helpful to you, then do the decent thing and click the THANKS button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. This is the proper way to show your thanks for the time and help someone gave you.
To be be fair, the xb10A was a bit of a pig to install given its size, as you are probably well aware its very big. What is the absolute ideal db signal strength? Ideally i would have wanted to hit 60db just to keep it nice and round, is 57db which I have too low for your liking? Do you think given that I have very high quality strength (100%) for all frequencies, I would get away with a masthead amp just to give the db strength a small increase?
About signal quality, how low can that drop before things go pair shaped,what are the limits? Having done a bit of research I hear that the quality is far more important than the strength itself.
I have no issue buying a log36 or masthead amp if you think it would be better?
thanks
 
As I said in post #4, 55-65dBuV for signal strength is what I'm aiming for when installing. Bear in mind though, I have the gear to read the strength from each mux individually whereas your meter does an average of the whole lot. I might see a spread of 3-5dB across at all the major muxes, from lowest level to highest level. That means I try to keep the lowest-powered mux at 55dB or above, or the highest powered mux at 65dB or lower. That's my personal choice as an acceptable window. However, most TVs will be quite happy with 50dBuV and will also work on less. Again, that's what I wrote in post #4.

The strength is only part of the puzzle though. Signal quality is far more important; I've said it and you've found it out for yourself too.

If your system works then I wouldn't spend money changing it now unless the higher channel muxes show symptoms of drop-out when the weather gets bad.

ATV recommends a Group A aerial for Craigkelly based on the main 6 muxes (PSB 1~3, COM 4~6). They don't factor on COM 7 & 8 because these are temporary muxes that will be switched off for all transmitters by 2022 I think. When they go, Craigkelly will be a Group A transmitter.

If this or any other reply was helpful to you, then do the decent thing and click the THANKS button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. This is the proper way to show your thanks for the time and help someone gave you.
 
Thank you, In that case, I will leave it as it is, like I say, I get all channels, even from 55 and 56 even though the strength on them is only 35%, but as you have confirmed Quality is far more important which is why its all working, its 100% for all muxes, I will keep an eye out when the weather changes,if I lose a few channels I would be that bothered, I obviously will not be watching them all, However it all turns out, its certainly much better than being ripped off by virgin media.
 
Hi all, one last thing, Forgive me if its a daft question, but I noticed on the 6 way splitter it has two screw terminals on each side,what exactly are these for?, Earth bonding maybe? I have a cold storage tank in the loft with copper pipes that are all bonded, so I could bond the splitter to this (if that's what the terminals are for?), what exactly will this achieve, is there any point?
Other than that the system is working fine, I'm pretty happy with it all.
thanks.
 
Where a splitter is used in a block of flats or some other multi-dweller building then earth bonding is a legal requirement. It helps to protect the residents/users from any potential stupid act by one of the other users.

In a domestic setting the benefits have to be weighed against the risks.

Your home's electrical supply is protected by a fuse box. Maybe it has RCDs. Chances are then if 240V mains did find its way up an aerial cable then that whole circuit would trip out. That would protect each room in the house from the others. I don't know if Earth Bonding would offer any extra protection in that situation.

The con is the increased risk of a lightning strike. A bit of metal sticking up at potentially the highest point on a house is a risk on it's own. Most electrical items are now double earthed, so theres no direct path to earth via a mains plug. Adding a juicy fat route to earth via Earth Bonding a domestic aerial system might be just what an electrical storm is looking for as a discharge point. If there's no other structure higher that is also earthed then there's a risk you could be looking at fried electricals, building damage, or worse.

Personally, I wouldn't earth bond a domestic aerial system without a very good reason to do so.

If this or any other reply was helpful to you, then do the decent thing and click the THANKS button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. This is the proper way to show your thanks for the time and help someone gave you.
 
Thank you, In that case, I will leave it as it is, like I say, I get all channels, even from 55 and 56 even though the strength on them is only 35%, but as you have confirmed Quality is far more important which is why its all working, its 100% for all muxes, I will keep an eye out when the weather changes,if I lose a few channels I would be that bothered, I obviously will not be watching them all, However it all turns out, its certainly much better than being ripped off by virgin media.

I keep weighing up our Virgin Media subscription, problem is their broadband is excellent and heavily used by the children.

What did you do internet wise?.
 
Personally, I wouldn't earth bond a domestic aerial system without a very good reason to do so.

I disagree. With a multiway splitter feeding several sets there is quite likely quite a bit of leakage which can cause a nasty tingle.

I don't think it would encourage lightning either, lightning is such a high voltage that the insulation provided by an unearthed aerial is neither then or there. But to be safe fit a lightning arrester, earth the aerial via a heavy lead to an earth rod.

In many countries it is mandatory to earth aerial systems.
 

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