[asathorny]

All done and dusted OK.

After a hiccup with the lounge TV - found to be a less than perfect fitting of the connector on the end of the cable - both sets are working fine on Freeview with no loss of signal, no pixellation and good audio. We are 13 miles as the crow flies from the transmission mast mainly over rural landscape with no hills or high buildings on the direct line and appear to enjoy a strong signal.

The programmes are still crap though...............

Well done Alan, us awd un's can still get the job done 

Good effort Alan.. Glad you got a successful result 

Wish ours was that simple.. We have a substantial hill with lots of trees between us and the closest transmitter which is ironically probably only 2kms at the most away  With our set up we pull a similar strength of signal from the Launceston Transmitter which is also behind the hill and probably 100kms away..

Our setup is:

91 element High Gain UHF antenna AND a quality Phased array antenna connected "backwards" via a Diplexer with the combined signal fed through a good quality Masthead amplifier all mounted on a 10 foot tethered pole.

The good quality coax follows a steel cable into the roof cavity (about 10 metre run?) to a 4 way splitter/booster..

Unfortunately because our house is large the runs from that booster to the various sets vary between say 15 and 30 metres.. (fortunately the 30 metre run is to my office and combined with the weak USB tuner I use in there I only get  a couple of the more popular channels on the computer) our two main TVS are pretty stable on all channels now (mostly)

No doubt Dazz you have set this up with some professional advice. The things to remember when dealing with fringe/low signal levels is that the signal to noise ratio will never be better than that found directly at the antenna terminals and this is why a mast-head amplifier is connected as near as possible directly to the antenna (a diplexer does not help) to avoid any cable losses. A mast-head amplifier is less concerned with amplifying than maintaining the all important signal to noise ratio and is designed accordingly.

What you do with the signal after the mast-head amplifier can never improve the signal quality only is strength. The signal from here on in is simply amplified if and as needed to overcome losses in cables and splitters etc used in the distribution network.

The best way to improve a weak signal is to raise the antenna.  Any extra signal comes free of additional noise that any amplifier must introduce. Of course it also helps to have a high gain antenna system that could be made up of stacked antennas. Anything you can do to get a better signal from the antenna itself is best. Again, it's the signal to noise that's most important and it will have been determined by the time you take your signal from the output of the mast-head amplifier which will have already made it worse anyway.
 

[Dazzler]

Thanks Pip ..

I actually set most of it up myself but had a short which was stuffing things up when we first moved in so did get a bit of help from a guy with a meter and more experience than me.

I didn't realise until You (i think) and our tech at work said it, that the longer aerial with more elements is fussier about direction  So, if I cant borrow a meter or a bloke with a meter I will study google earth to see if I need to swing the aerial a bit to improve the quality(rather than trial or error)   

No it wasn't me that mentioned about critical direction but a reasonable analogy (and I know you are a photographer) is to liken a longer antenna (a generalization as not all high gain antennas are longer - most configurations are though) to a "longer" lens. A longer lens narrows the field of view and as you know if you don't point it carefully, what you are looking for is out of the field of view and (the signal) will not be captured!

It's a little more difficult to see changes in the digital signal strength by looking at the picture, unlike analog, so turning the antenna while an observer watches the screen is not as obvious.  What I'd try though would be to find the extremes of angle where the picture drops out or pixilates etc. and then set to the centre of that angle. Remember how we used to tune the wireless in the old days? Left, right, centre. Or what I suggested to Alan, most digital devices have a signal strength/quality indicator. While usually crude, all you need to see is a reliable variation as the antenna is swung around.

Once you've done all you can and you are sure the amplification is sufficient to overcome the losses then as I said stick it up higher. I'm guessing you put it up the hill to get a height advantage without having to use a longer pole and that would be good but 10 feet is not high really. Another 10 feet might make the world of difference.

I use to work in country areas with, I'm guessing, about 50' towers in the early days of TV. 
 

[baroudeur]

All done and dusted OK.

After a hiccup with the lounge TV - found to be a less than perfect fitting of the connector on the end of the cable - both sets are working fine on Freeview with no loss of signal, no pixellation and good audio. We are 13 miles as the crow flies from the transmission mast mainly over rural landscape with no hills or high buildings on the direct line and appear to enjoy a strong signal.

useful - because Stechford is only 15 minutes from my home.

Well done.

Did you use Hardy?  I guessed from your Solihull address that they would close enough to use.

[AlanHo]

Did you use Hardy?  I guessed from your Solihull address that they would close enough to use.

I'm afraid I cheated - I looked at their website and identified the bits and pieces I needed - then bought them from Screwfix depot which is just 3 minutes from home. If I had required a booster - then Hardy's would have been the the place to go.

Thanks for your advice anyway - it was most useful.

[Dazzler]

Once you've done all you can and you are sure the amplification is sufficient to overcome the losses then as I said stick it up higher. I'm guessing you put it up the hill to get a height advantage without having to use a longer pole and that would be good but 10 feet is not high really. Another 10 feet might make the world of difference.

I use to work in country areas with, I'm guessing, about 50' towers in the early days of TV.

Thanks again Pip .. I have cemented the pole in so I wont be moving it. I chose the highest point of our block that was relatively close to our house (to minimise the cable run) which fortunately means that the ugly pole and aerials are mostly hidden by the house.

I will use the signal strength and quality meter on one of our PVRs to get the direction optimised   

[Phil №❶]

I have cemented the pole in so I wont be moving it.

Yep, that a real good earth you've go there 

Once you've done all you can and you are sure the amplification is sufficient to overcome the losses then as I said stick it up higher. I'm guessing you put it up the hill to get a height advantage without having to use a longer pole and that would be good but 10 feet is not high really. Another 10 feet might make the world of difference.

I use to work in country areas with, I'm guessing, about 50' towers in the early days of TV.

Thanks again Pip .. I have cemented the pole in so I wont be moving it. I chose the highest point of our block that was relatively close to our house (to minimise the cable run) which fortunately means that the ugly pole and aerials are mostly hidden by the house.

I will use the signal strength and quality meter on one of our PVRs to get the direction optimised   

The antenna position should ideally be chosen using a signal-strength meter but unless there is a particular obstruction the highest convenient point will normally suffice. In other words, the one you already chose! 

What I was trying to say was the position could have been any (sensible) distance away from the house so long as the amplification (after the mast amp) numerically overcomes the cable/splitter losses. The signal to noise ratio is set by the antenna/amplifier and thereafter is not affected by the length of cable or whatever comes after that so long as you don't let it fall to a level that allows the next amplifier in the chain to introduce its own noise.  That next amplifier, if you don't interpose another, will of course be the TV or whatever.

Each split of a signal halves it (sounds reasonable to me) which expressed in db terms is -3db (each halving or doubling of power is -/+ 3db). There is a slight additional loss to inefficiency so a 3.5db loss is what you get from a 2-way split. A 4-way split is made by cascading a 2-way with an additional 2-way with each output leg. Each output loss after the 4-way split is then simply 3.5 + 3.5 = 7db and so on.

The loss for RG6 is about 3db/20 metres. Add it all up and the amplifier used to overcome the losses will be losses plus some safety factor of 5-10db.

A 30 metre cable plus a 4-way splitter would then have a (say) 20db amplifier to overcome the losses. The amplifier would need to be before the splitter and if you use a integrated combined amp/splitter unit then you can be assured that's how they make them.

One more point about the cable: losses will vary by frequency so that the upper UHF frequencies will be attenuated more than the lower VHF. All RG6 is not made equal so if looking for the best performance choose quad shield. The type of dielectric is also important. Anyone looking for this level of information will know how to find any further info.

And Dazz, at the risk of repeating myself,  if your current setup WRT amplification etc. is still problematic, my suggestion as before is just  add another 3 metres to the pole.

[Dazzler]

Thanks for the advice Pip but adding another 3 metres to the pole would be an enormous job (unless I hired a cherry picker) But all the info is handy I am a big sponge with stuff like that (helps to understand all the variables)

I had to go for a drive to find exactly where the transmitter was in relation to our house. I couldn't spot the Transmitter on google earth but found the house it was just behind.. The laneway behind our house is pointing straight at the transmitter. So I might have to tweak the direction slightly as the antenna is running parallel at the moment should perhaps point slihtly towards it. Might try this or wait until I can borrow a meter.

[Phil №❶]

I used garmin mapsource to work out the bearing to the towers & a mobile phone with compass to point the aerial. 

[Dazzler]

I used garmin mapsource to work out the bearing to the towers & a mobile phone with compass to point the aerial. 

I have a Garmin 1390T and a HTC wildfire can I do that? (could you PM me with advice please Phil) 

I got a Twin Tuner PCI card for our PC to replace the USB Tuner I was using (now getting most channels in my Office) 

[Doggie 1]

You got a very good reception on this thread Dazz 

[Dazzler]

You got a very good reception on this thread Dazz 

It's all Alan's fault (he started it) 

[AlanHo]

It's all Alan's fault (he started it) 

Bloody cheek - the thread was about my aerial and you hijacked it...........I hate it when people blame to dog.......... ...

[Doggie 1]

I think there was a splitter in the middle. 

P.S. I blame the dog for lots.

[baroudeur]

I used garmin mapsource to work out the bearing to the towers & a mobile phone with compass to point the aerial. 

There is a website that allows you to check if there are any  topographical height obstructions to a line of sight between your house and the transmitter and the compass bearing to it.  Will try to find and post it.

[AlanHo]

I used garmin mapsource to work out the bearing to the towers & a mobile phone with compass to point the aerial. 

I could do the same since I have Mapsource - but for those that don't - Google Earth can help in conjunction with your sat-nav.

You can add a placemark on Google Earth for your home and for the transmitter. Then use the ruler tool in Google Earth to plot a line between these points. Then use a protractor to measure the angle from a compass point.

If you don't know the coordinates - drive there and use your sat-nav to show them.

[Dazzler]

 

[Lorian]

I used garmin mapsource to work out the bearing to the towers & a mobile phone with compass to point the aerial. 

There is a website that allows you to check if there are any  topographical height obstructions to a line of sight between your house and the transmitter and the compass bearing to it.  Will try to find and post it.

http://www.wolfbane.com/articles/tvr.htm

find the transmission path predictor.

[baroudeur]

Thanks for the link but there is no topographic mapping on it unless I missed it.

Th website I recall had a map of the line between address and transmitter and a diagram of the topography in between the two  which showed any high ground that would interrupt the line of sight.  It assumed the address had an aerial 10 metres a.s.l. and used the height  a.s.l. of the transmitting aerial.