Picture break up on Aura

MikeSh

MikeSh

Well-Known Member
Unusually we were watching a programme on SWMBO's Aura last night (my own and joint stuff is usually on the satellite box) and the picture and occasionally sound were breaking up frequently throughout. This was a recording from ch4HD. She said she often gets this, but she's never mentioned it before and I don't know what channels might be involved.

I've just been doing a bit of digging this morning. The live TV is all fine. I set up 4 instant recordings, one on 4HD and three on various other minor SD channels, to get all 3 tuners working to test them and get signal strengths. All worked but (a bit to my surprise) showed signal strengths in the 95-100 range ... I'd expected 70-80ish from experience with our (now retired) FOX boxes in the past. Qualities all 100.

So is this a too much signal situation?
Is the Aura strength indication much different from the FOX?
Is the Aura more sensitive than the FOX?
Has Rowridge increased its power output in the last year or so?

The aerial signal is amplified, but this has been the case for many years and was needed to get sufficient signal for reliable operation of the FOXes.
 
MikeSh said:
So is this a too much signal situation?
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The quality figure would take dives if it were.

MikeSh said:
Is the Aura strength indication much different from the FOX?
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Impossible to say, we're not given any specification for what "100%" means for any particular item of equipment, nor what that is relative to saturation.

MikeSh said:
Is the Aura more sensitive than the FOX?
Click to expand...
As above.

MikeSh said:
Has Rowridge increased its power output in the last year or so?
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I very much doubt it!
 
MikeSh said:
I've just been doing a bit of digging this morning. The live TV is all fine. I set up 4 instant recordings, one on 4HD and three on various other minor SD channels, to get all 3 tuners working to test them and get signal strengths. All worked but (a bit to my surprise) showed signal strengths in the 95-100 range ... I'd expected 70-80ish from experience with our (now retired) FOX boxes in the past. Qualities all 100.

So is this a too much signal situation?
Click to expand...
It might be; the only way to find out is to use a variable attenuator to reduce the signal strength and see what happens.
Is the Aura more sensitive than the FOX?
Click to expand...
My reading of what I have seen posted about the Aura is that it is less sensitive which would make sense as the HDR-FOX T2 is a pre DSO design and the Aura is a post DSO design.
 
Hmm. Well that's all a bit strange.
As the Aura can do four concurrent recordings could it be a disc overload? (The recording was done while I was away, so I've no idea if that was the case.) Now I'm aware of the problem I'll try to collect more info on which recordings are breaking.

prpr said:
You've got both units, so why don't you...
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The one FOX we still have is stored away. Be a bit of a pain to get it back into the system.

MartinLiddle said:
It might be; the only way to find out is to use a variable attenuator to reduce the signal strength and see what happens.
Click to expand...
I'll have a poke round to see if I can get something to try.
It's annoying that the amplifier is the split type with the psu by the box/TV and the power fed up to the loft via the coax, so I can't easily take it out of circuit. I might try just killing the power but I suspect that will poleaxe the whole signal.
 
Black Hole said:
The quality figure would take dives if it were.
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Well I don't if that happened at the time of the recording. The figures I give above were just while I was testing and I didn't see any break up of pictures at that time.
 
MikeSh said:
Hmm. Well that's all a bit strange.
As the Aura can do four concurrent recordings could it be a disc overload? (The recording was done while I was away, so I've no idea if that was the case.) Now I'm aware of the problem I'll try to collect more info on which recordings are breaking.
Click to expand...
On the rare occasions I have 4 recordings in progress I haven't seen any signs of hard drive overload although most of my recording is in SD
I'll have a poke round to see if I can get something to try.
Click to expand...
I don't suppose the amplifier has variable gain?
 
prpr said:
Still would mean going in to the loft, which seems to be the tricky bit.
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:roflmao:
Not that bad actually.
I've had the unit open for wiring a couple of times over the years and I don't recall noticing any adjustability, but it might be worth a look.

I've ordered a variable attenuator which will be easier to fit and fiddle with, so I'll try that first. If it fixes it then I'll go up and see if the amp can be adjusted or even remove it completely, depending how much attenuation the variable thing needs to work.
 
ROWridge has two polarisations transmitted simultaneously for a reason to do with interference from the Continent.
Effective Radiated Powers are:
Horizontal: 200 kW for the 3 PSB muxes and 50 kW for the COMs (-6 dB).
Vertical: 200 kW for all 6. {This polarisation gives better interference protection.}

Is your loft aerial Hp or Vp? What date was that recording? Might it have been during a High Pressure, enhanced propagation time? = a greater likelihood of interference?

Perhaps worth checking your 'detailed view' interference predictions? https://www.freeview.co.uk/corporate/detailed-transmitter-information to see if the numbers are poor and/or different for the HD (BBC B) mux on frequency ch 21+ at your location when receiving Hp vs Vp?
 
It's not a loft aerial - the amp is in the loft. The aerial is a high gain on a tall mast outside.
It's horizontal because in the past the vertical from Rowridge didn't carry all the muxes, but it seems that issue has gone away now the shuffling is over.
Vertical looks a better choice now as all those muxes are 200kW, but if we are over-powered that isn't an issue.

Got a bit more from SWMBO in that a channel 5HD programme was also breaking up. 5HD and 4HD are both on 21 which I think was the one bouncing against the 100 reading, so I'm pretty sure this isn't a weak signal issue.

The attenuator is due someone today so I'll play around over the next few days.
 
prpr said:
You've got both units, so why don't you...

No.
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I decided it was time to remove the old and oos satellite box which left a space and connections free, so I dug out the FOX and did some comparisons of the strength indications.
C25, aura 58, fox 51
C21, aura 96, fox 77
:confused:
The FOX readings are about what they were in the past, so clearly the Aura is different in some way.
 
Rodders53 said:
Only the temporary COM7/8 muxes were Hp only. The main 6 were always Vp at the same 200 kW erp at DSO.
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I know. We wanted com 7&8. I actually added a second aerial to get them as they were a different group.

Rodders53 said:
No harm in reducing the input level to the Aura as a test, of course. A passive 2-way splitter is -4 dB if you have one.
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It's actually on a splitter with the TV already.

Rodders53 said:
Freeview website https://www.freeview.co.uk/corporate/platform-management/planned-engineering-works has planned work listed for Rowridge (from 24th July).
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Oh, that's interesting. From the way SWMBO spoke I got the impression this was a longstanding issue. I'll need to do some more interrogation.
 
prpr said:
That's weird. What are the other 4 (or 5 if you get Local) muxes?
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I only did those two. It's a pain on the Aura as you have to tune to a channel that is on the mux you want, then dick around to burrow down to the meter screen, read it, work back to live TV again, repeat ... **
Those two cover a 200kW HD and 50kW SD and I couldn't be bothered to do more. Sorry.

( ** Unless @MartinLiddle or someone knows another way to do this. On our also android TV I couldn't find a signal meter at all, though I expect it's in there somewhere.)
 
Intriguing.
Found the signal meter on the TV. C21 100 (or 100+), C25 93.
Also tried turning off the amp and, as expected, it poleaxed the signal and quality.

SWMBO says the pixels has been happening for a long time but has been worse the last week. I guess I'll have to wait for the engineering to finish before going much further.

As the V has 200kW for all the muxes, I'm tempted to change the aerial to V and get rid of the amp, which is probably only needed for the 50kW muxes. Would probably save a few £ a year in electricity. But that's getting ahead - need to try and bottom this pixels issue first.
 
Interesting. My -T2 on Sandy Heath measures 71% on ch 21 (HD); 75% on 24 and 48; then 74% on 27, 33 & 36. All 6 are at an identical erp. The aerial in loft is a bacofoil wideband 'high gain' job {came with the house} and likely droops in gain at 21 cf the rest.

Access to the diagnostic signal metering on Aura sounds very similar to the process needed with a Foxsat-HDR to check out the different transponders, but harder.

I'm surprised at the wide difference for only 6 dB erp levels on the -T2 77 to 51 %. But at least the Aura gives similar(ish) level differences on the same frequencies.

Turning off the amp psu gives the expected zero signal. Using the -T2 as a reference tuner meter suggests you'd get the same 77% on all muxes with the amplifier (and passive splitter) if you switch to Vp. If that amp is 6 to 8 dB gain only 51%?? I doubt you'll get away without any amplification although some say the -T2 works fine with lower input levels. It's also possible the masthead has much higher gain?

Meters are different on different devices: I have had Panny TVs that report 100/100 (or 10/10) as they were post AGC and Error correction. One even showed the same before DSO and after, when the power increased by 10 dB. They are not invariably useful; only if they work like the -T2 metering does!
 
Rodders53 said:
I'm surprised at the wide difference for only 6 dB erp levels on the -T2 77 to 51 %.
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I'm not. I noticed a bug in this metering 5 years or more back, which I reported before, though no-one seemed interested. It appears unable to display 56-65%; when the signal crosses this boundary it jumps directly from one side to the other. So that 51-71 is more likely 51-67 or 61-77 (ie. delta 16 not 26).

I did identify the amp back then too. It's a Fringe Electronics one, but I can't remember which model now. IIRC it is about +12db. I actually have another amp in the loft (left over from the Com7/8 days which is switchable hi-lo something like 12-7db, so I have a few options to hand.
 
MikeSh said:
I only did those two. It's a pain on the Aura
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I meant on the T2 (even if I didn't write it!). I think you might have a notch or some other odd effect (maybe cross-mod. if your amp. is overloaded or otherwise unhappy), hence the request for all the figures.
 
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