Help with signal strength & quality

[eskimo]

Hi guys, I am just working towards my NVQ and for one of my assessments I am doing a job for my auntie.
She has had an aerial up at her static caravan for the last 5 years which she is sure worked fine up until around 9 months ago. When I went around the terrestrial channels 1,2,3,4&5 were all there but very bad quality (Channel 4 was the best although still a biz hazy) But on freeview she was only getting 6 BBC channels, from what I understand it would seem she is only receiving one of the 6 multiplexes from the transmitter.

I checked around the wiring and also found a Triax amplified splitter under the caravan with 1 in and 2 out (1 to the lounge & 1 to bedroom) however this was badly installed and full of water. Also the cabling used throughout was copper plated with an air core.

I started off replacing the cable for Webro WF100 and removed the amp/splitter for the time being. I attached my Horizon test meter and began moving the aerial to see if I could get any better signal strength or quality. After a bit of playing around the best I could get was:

MA - DVB-T
30 dBUV
26 dB

BBC1 - PAL-I
46 dBUV
34 dB

MB - DVB-T
34 dBUV
28 dB

ITV - PAL-I
44 dBUV
33 dB

MD - DVB-T
30 dBUV
28 dB

MC - DVB-T
27 dBUV
22 dB

BBC2 - PAL-I
44 dBUV
37 dB

M1 - DVB-T
37 dBUV
31 dB

C5 - PAL-I
40 dBUV
36 dB

M2 - DVB-T
37 dBUV
28 dB

C4 - PAL-I
48 dBUV
41 dB

The aerial is mounted on a pole around 3 meters tall and is roughly 21 miles away from the Emley Moor Transmitter.

Firstly can anyone recommend whether an amplifier would be the best option? A new aerial & Amplifier or whether I need to look at getting the aerial on a taller pole???

Sorry for such a newby question but I am having to teach myself from books as my NVQ is a bit of a joke with no real classroom work (I have just paid to attend a 2 day private course in March but thought I would get this done now for my portfolio)

Also how do I know how high to put an aerial if it is not on a roof and I cannot see the transmitter or is it just a case of the higher the better?

Secondly is there any rule of thumb for choosing an aerial or is it worth keeping a few different sizes in stock to enable me to try a bigger on if the first doesn't work?

Finally (Sorry) what would be the minimum dBUV and dB levels to get a good digital reception?

Sorry for such a long thread and thanks in advance.

 

[Lazarus]

First question: Is Emley Moor the most suitable source?

 

[eskimo]

Thanks for the reply. I would believe so as all others in our area seem to be relay transmitters. Wharfedale is closest as it is about 2 miles over the valley, however my house points at this as I am in the base of the valley and I only get 1,2,3&4.

Here is a list of transmitters and the green dot is approximately where my aunties static is.

 

[Analoguesat]

Dunno about the nvq requirements but how about a satellite solution instead?

I know Wharfedale pretty well - I worked at Malham Tarn for a couple of years a long time ago - and theres some big hills around there that block signals.

 

[Robbo]

Go to the digital UK website and check what you should be receiving from your postcode from the transmitters around you. Also check that the aerial used is of the correct group. Looking at your figures, some of the signal levels are lower than required. You may need a higher gain aerial.

 

[eskimo]

Thanks for the replies guys, the area is a nightmare to try and get a decent signal as the whole area is inside a bowl shaped valley. Her neighbor it pointing at Emley Moor so I figured it would be the best to aim for. I have just checked the Digital UK site and this gives it as an option. It also states aerial group as BH? What does this mean?

Thanks for all the help guys and sorry to be so clueless at the minute, I am struggling to find any decent way of learning.

 

[eskimo]

PS here is the transmitter location:

 

[Analoguesat]

BH = group B aerial set with the elements Horizontal - horizontal will be correct for for the Emily Moor station - the piddly power relays will be vertical polarity.

The big problem you will find when Yorkshire udergoes DSO is that the relays only carry 3 of the 6 multiplexes ("Freeview Lite") so the residents who cant get Emily only get half a service!

 

[Lazarus]

And does her neighbour have more success at getting all the DTT Muxes?

 

[eskimo]

BH = group B aerial set with the elements Horizontal - horizontal will be correct for for the Emily Moor station - the piddly power relays will be vertical polarity.

The big problem you will find when Yorkshire udergoes DSO is that the relays only carry 3 of the 6 multiplexes ("Freeview Lite") so the residents who cant get Emily only get half a service!

Many thanks mate. I have tried to find a course either block or day release where I can learn about aerial/satellite installation but couldn't really find anything. A company near where I live offer a 2 day aerial course and a 2 day satellite course for £220 each plus VAT so I have booked the aerial one. I don't think I need the satellite course as I only intend to offer Freesat and after buying a few dish/receiver kits for family and friends seem to have experienced any problems installing them. So it seems Freesat will be the only way to get all the channels around here, do you know what will be missing from Freeviewlite?

I know this is probably a stupid question but how do you know how high to put an aerial?? Is it just a case of keep going higher until the signal gets stronger?

Is there a minimum dVUB and dB level I should be looking for? eg.
60 dBUV
80 dB

Am I correct in thinking the dBUV is the strength of signal and the dB is the quality? If so would the higher gain aerial increase the dVUB which in turn should increase the dB??

What would a mast amplifier do?

Thanks again to everybody and I am sorry for taking up your time.

 

[Analoguesat]

Cant help you with the tech aerial questions - Im not an installer, but basically Freeview Lite gives you the PSB channels muxes on DTT

Here in the Borders we have one main transmitter (Selkirk) and around a dozen relays.

Selkirk is the only transmitter to be carrying all six muxes - all the relays only get 3. Now Selkirk only serves 48% of the population, (and virtually none of the reasonable sized towns - it doesnt even cover Selkirk properly!) so i'd say we got shafted..

 

[eskimo]

It would seem this is the same where we live. I guess I might be better offering Freesat as my main product.

Thanks for the help mate.

 

[Analoguesat]

To be honest with you eskimo, I recon satellite is going to be a better option Anywhere in the Dales valleys around there that doesnt have los onto Emily Moor.

Anyway a zone 1 dish is going to be much easier to hide than a massive great multi element tv aerial! (Especially if you offer bespoke spray painting to blend it into the background in any sensitive installs (Car primer paint)

You can offer FreesatfromSky or Freesat as options as well!

 

[Robbo]

The minimum recommended signal level for DTT is 45dBuV.

 

[eskimo]

Thanks very much Robbo, do you think a High Gain aerial would do this or is there a chance that an amplifier would be better?

 

[Lazarus]

< Emily Moor...................>

Old girlfriend?

 

[sonnetpete]

Old girlfriend?

Didn't she live in a caravan and was one of the Pontop Pikey's?

 

[Llew]

No, she got hitched to Sandy Heath, the tinker.

 

[sonnetpete]

No, she got hitched to Sandy Heath, the tinker.

....then divorced him and ended up parked on Oliver's Mount. (and on that note I'll collect my coat and be leaving)