Picture break up on Aura

[Rodders53]

PLEASE
Do make a full set of Signal/Quality measurement on both Aura and your -T2 before altering the aerial.
and Repeat them when canted over to Vp.

I'd really like to know the Field numbers from Wolfane for Rowridge Vp and Hp (though it should be -6dB on Vp as Wolfbane gives the number for the weakest 50kW muxes).
That'll allow gain loss calcs to see if the system provides the ideal 45-65 dBuV at the outlets.

The aerial amp has two +18dB outs... that's high level for sending signals down very long cables / to passive split outlets. On any multiple outlet Distribution Amplifier with a FULL (+18dB) outlet the makers supply a terminator. Read what Justin writes about this particular issue https://www.aerialsandtv.com/knowledge/splitters-amps-and-diplexers#amplifier-terminators

I must also say that you should remove that aerial combiner from circuit... or at least terminate (?short?) the other input to prevent anything stray/direct pickup from getting into the masthead amp at the higher frequencies.

 

[MikeSh]

I'd really like to know the Field numbers from Wolfane for Rowridge Vp and Hp (though it should be -6dB on Vp as Wolfbane gives the number for the weakest 50kW muxes).

This is the result, which is as useless as all the other predictors. There is too much local variability round here with aerials pointing different directions and/or polarities on adjacent houses or even the same chimney stack. (It's a mix of all the ones in that list from what I can see, though probably not Salisbury.)

 

[MartinLiddle]

This is the result, which is as useless as all the other predictors.

It is interesting though that Wolfbane thinks you don't need an amplifier for Rowridge VP or HP. If moving to VP doesn't fix the problem then I would suggest that you try at least temporarily to bypass the amplifier.

 

[Rodders53]

13 miles from Rowridge on that bearing is Fawley/Hythe area.
There's nothing topographic that obstructs the view to the top of the mast - the antennas are over 280 above sea level. Only local trees / buildings / structures (Fawley refinery?) might do that (and or cause unwanted multipath reflections = bit errors).

Lets assume Wolfbane is approximately correct with the calculation of field from the distance.
71 dBuV/m + 10 dB aerial gain (minimum) - 2dB cable/termination loss -1 dB filtered combiner loss + 18 dB masthead gain - 4 dB (2 way passive split) and - another 2 dB cable / termination losses = 90 dBuV.

Only 25 dB over the max ideal. {Or 19 dB for the -6 dB COMs in Hp}.

To be frank that's wet string territory.
FYI I'm 11 miles from Sandy Heath (180kW/170kW erp) and have a Wolfbane predicted Field of 69 dBuV/m. My aerial is in the loft (-10dB loss for bulding materials + 10dB for the aerial) and is split 2 ways before being split again behind to my -T2 and main TV (-8dB splits and -3dB cable / termination losses). So around 58 dBuV.
My bedroom TVs work with a simple dipole aerial (one home made). Not 100% reliably if they get moved, but good enough for some casual TV watching.

Start from the basics.

Get some F plugs (twist on Proceptions than Justin recommends) are https://www.toolstation.com/proception-f-plug/p56253 £2.79 for 10 (get 20) and barrel joiners https://www.toolstation.com/proception-inline-coupler/p97650 £4.49 for 10. Under a tenner, total (unless you need them posted have to travel to collect). CPC Farnell may be cheaper in that case for the items with small order surcharge/delivery. They sell plugs under their part code CN23149 14p each for 10+, joiners CN16097 24p each, 10+and even do 75 ohm terminators: they are CN19897 and 31p each.

Then you can rewire the existing cables and stuff.

Take the aerial direct to a single TV/PVR. No amps/power supplies. No filters. No splitters.

What do the PVR signal meters report then (measure with both Aura and -T2, in turn for a good benchmark).

Then start adding amplification and distribution splitting and re-measure to see the effect of each action.

I know it is a lot of time consuming work (and not ideal in a loft space if access / flooring is poor - even just the heat in an attic space can be awful. But I think you have no real choice if you want an even semi scientific analysation to take place.

I'd strongly recommend that you do the above measurements before altering the aerial polarisation. It's safer than climbing up and working at heights.

If you do go outside and up to the aerial level... check the view towards Rowridge. What is in the way that you can see? (Google Streetview and satellite imagery may also help on this?) Trees can be a real pain to reliable TV reception, sometimes.

 

[MikeSh]

There's nothing topographic that obstructs the view to the top of the mast

Yeah, right.

What is in the way that you can see?

I can see about 70m before the trees block the view. Beyond that there's near a kilometre of ground rising about 15m above us with a topcoat of housing and woodland.

We used to live 30 odd miles from Winter Hill and had no reception problems as we were nearly line of sight. This is a different ball game and the signal checkers are useless.

 

[prpr]

What is in the way that you can see?

I've just had a 'drive' around and it's... trees. Big uns, too, and fairly dense. It's fairly easy to spot his XB16A.
Interestingly, in 2012 there were a pair of stacked things (not a great view) on the back of the house on a very long pole. Now it's on the side. No wonder there is grief, which is probably why the stacked aerials were there before, and explains the odd notch mentioned previously. As you say, the terrain is clear otherwise. Chainsaws and bulldozers probably needed, or another 1987.

 

[Rodders53]

Trees then. Reception killers and variable frequency attenuators/reflectors giving standing waves and other issues. Especially when wet and windy. Probably not possible to get 'under' the foliage for a clearer view with an aerial?.

Grid aerials are fairly good at receiving through foliage. Better than the log periodic on a Reception Survey vehicle. (Analogue).
https://www.aerialsandtv.com/product/grid-aerial-2 {that picture is of one in Vertical polarisation}.

There's one not far from you. Ask them how it works?

You're blaming the prediction tools for something they cannot take into account. It's why local aerial installers have tried alternatives such as Hannington - presumably using signal meters.

I still reckon you've got too much amplification involved.

@prpr The stacked pair were probably a group A for the main 6 plus a wideband for COM7/8 that have been mentioned before (with that filtered combiner still in the signal path). Not a 'phased array' stack https://www.aerialsandtv.com/knowledge/aerials#phased-array-aerials

 

[MikeSh]

Interestingly, in 2012 there were a pair of stacked things (not a great view) on the back of the house on a very long pole.

Yes, that was a grid aerial (4 section iirc) that we inherited along with the amplifier. The signal was marginal on the low power muxes and I had no idea of its age or history.
When we decided to have a large conservatory built at the back access to that aerial and pole would have been difficult, so I installed the XB at the side, swapped over, and then removed the grid and pole before building work started.

Chainsaws and bulldozers probably needed

Pretty much all of these trees are on public/council land and there seem to be blanket preservation orders on them.

 

[MikeSh]

There's one not far from you. Ask them how it works?

That one is a smaller one facing the other way, so probably just getting Millbrook. But like most he's got a sat dish and probably isn't using terrestrial.

You're blaming the prediction tools for something they cannot take into account

I could forgive them for not spotting a single massive tree like the one that killed my reception 40 odd years ago in a new build house, but neither the ground level or woods are recent or very localised.
You were the one asking for the predictor results and in post 44 above using them to tell me I had fantastic signal strength, but clearly those results are almost worthless. I suspect they just use the distance to the transmitter and its polar diagram to work with.

 

[Black Hole]

I suspect they just use the distance to the transmitter and its polar diagram to work with.

And perhaps the topographic data, but that's just the ground contours (ie hills) and does not include trees etc.

 

[Rodders53]

None of the professional spectrum planning prediction tools can account for building clutter nor trees. That stuff is simply not mapped fully, nor necessarily accurate and up to date. So the public domain ones simply cannot, either. It's why installers have test aerials and calibrated spectrum analyser signal meters (and the UK Planners use similar equipment and tools in survey vehicles when it is important).
The same applies to any RF signals (mobile phones etc.,.).

Wolfbane clearly states the assumptions made in its tool. Including that transmit antenna radiation patterns are not accounted for. (Freeview does as the UK spectrum planners have that data). However your direction from ROW would have no special restrictions (unlike towards France).
It's not uncommon for prediction apps to direct people to a transmit site on a hillside that's firing into the next valley along rather than towards the prediction location.

Wolfbane does have a clickable path profile plot that shows your downward slope etc.,. But the terrain height database is pretty coarse (fewer points). One can do ones own with OS maps, if desired and a scaled piece of paper.
Obviously very tall trees might well get into either the first fresnel zone or line of sight path. The Wolfbane one looks relatively ok, though for you with some clearance, but obviously not with more accurate real-life data you have.

I don't understand why - since you know it all about your location and it's reception so thoroughly - why you are persevering with such tenuous terrestrial reception at all.
Especially as you are reluctant to expend much effort on trying the suggestions made to you, in good faith, to investigate and improve the installation you currently have. Canting the aerial to VP should be the last thing to try imho.

NB Satellite provides more channels and a lot more in HD than terrestrial. Not sure if many (any?) are not on Freesat that are carried on Freeview?
Even streaming is now a practical alternative to broadcast reception for many. Though that does stop personal archive libraries of recorded programmes.

 

[MikeSh]

I don't understand why - since you know it all about your location and it's reception so thoroughly - why you are persevering with such tenuous terrestrial reception at all.

History really. It's all worked pretty well for 8 years or so, initially with our two FOX boxes, so there was no need to change really.

Especially as you are reluctant to expend much effort on trying the suggestions made to you,

The reason I'm reluctant to start messing and spending a lot for now is that soon after I started this thread it was pointed out about the engineering works that are/were affecting things. As example a recording of Yellowstone from about 3 weeks ago was dreadfully broken up, but the one a week later was fine. So it's not something I test easily.
I want to see if the problems continue now the works have apparently ended for now, but that will take a while, especially as SWMBO had been away for a week, so there is a backlog of recordings.

Turning the aerial to VP is almost a no-brainer as it will bring the whole spectrum up to similar high powers and costs nothing (though I will be watching for the law of unintended consequences to show its face). Buying and fitting terminators for unused legs will (according to ATV as linked earlier) possibly make a +or-1db difference, so I don't feel is worth doing at this stage. It's worked fine for years without them.

 

[MikeSh]

Satellite provides more channels and a lot more in HD than terrestrial. Not sure if many (any?) are not on Freesat that are carried on Freeview?

I'm tempted to get a second satellite system but it's tricky. Even with a wideband lnb it seems that sharing/splitting is tricksy and installing another dish and downleads will make it expensive. (I wish now I'd run a second pair of leads as a just in case when I was installing the new dish a couple of months back.)

 

[MikeSh]

Interestingly, in 2012 there were a pair of stacked things (not a great view) on the back of the house on a very long pole

I hadn't looked at our own streetview for a while and see they've updated the images. Most are from about 6 months ago I estimate. But if you drive right into the NW corner of the cul-de-sac that last location is an old view from before we moved in (2015). I guess the car didn't go quite far enough to get a new one for that.
Is that the 2012 view you mention? Of course you use a way back site? (It doesn't show any dates for streetview on this device.)

 

[prpr]

One can do ones own with OS maps, if desired and a scaled piece of paper.

We did that in Geography at school, aged about 15. Can't see kids today doing stuff like that.

Is that the 2012 view you mention?

This one:

Of course you use a way back site?

No, just Streetview on a PC and click on the dates. Devices? Pah.
There's a distinct lack of greenery on your corner since 2012 too, so somebody must have decided they could get rid of those particular trees.

 

[MikeSh]

somebody must have decided they could get rid of those particular trees.

Yes. But 'that corner' is actually part of our garden. As ever the estate builders had planted an assortment of stuff including at least a dozen large trees that obviously weren't going to coexist sensibly. So we thinned out down to 5ft high thicket with an oak, a Holm oak and a hazel (which I pollard to about 8ft over winter) sticking out the top. I suspect that sometime in the future even that may be too much, but by then it'll probably be someone else's problem and they might dig the whole lot up and plant olive trees or cacti given climate predictions.

No, just Streetview on a PC and click on the dates. Devices? Pah.

Oh I've not noticed that on the PC. I'll have a look next time I'm on it. I use my tablet a lot as it's more convenient than the PC most of the time.

 

[MikeSh]

I went for an evening stroll today as the weather has actually turned nice again, for now, and there do seem to be quite a few XB10 or lookalikes around our estate now. I'm wondering if I started a trend
I probably considered a 10 myself but, like the satellite dish, getting the next size up costs little more and is better than finding it's too small.

 

[MikeSh]

No, just Streetview on a PC and click on the dates.

Found it now. That's pretty interesting.

 

[MikeSh]

Had a go at turning the aerial to Vp today, but it produced some very oddball results*, so I put it back. Even then there was misbehaviour which appeared to be the coax to the Aura (the one that came in the box) and was apparently sorted with a different lead - I'm not certain it isn't actually the connection on the Aura, but we'll see.
The other stuff was probably my own stupidity, so with two possible rogue factors I might have another go sometime, but it's hard work and I need a rest for now

* One of them was the full power HD mux having only 95 strength on V instead of 98 on H, but in V the quality was bouncing around 50-75 with some picture breakup ... very similar to what happened when I tried using the variable attenuator. Other (SD) muxes run at 100 quality with lower strengths than that, so is there something different with the HD's sensitivity to strength?

 

[Black Hole]

Is there a risk of co-channel interference on V?