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Failing tuner?

OP
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pADDYB

Member
I think I'm back to my original prognosis - one of the tuners is failing. I've just tried playing BBC News HD while recording another channel (unsuccessfully) and it works fine with my original and new aerial.
 

MikeSh

Well-Known Member
Our boxes get about 40 strength on ch 55 and used to be OK. Recently one box has been struggling though the other seems OK still, but on that basis 50 should be adequate.
 
OP
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pADDYB

Member
Been away for a couple of weeks, but back on this now. Results of tuner test earlier in this thread. After trying a new aerial, I'm back to thinking that there is a problem with one of the tuners. I can still receive the problem channels if I am recording something, which suggests to me that one tuner works ok.

If it can't be repaired then I think I should look at getting a new box. I think the answer is "no", but given the age of these boxes, is there anything "better" I should be looking at? What I value the most is a reliable epg and series recording software, with some ability to manage clashes etc. I have access to some streaming services with catchup, but I still prefer to have the unencrypted recordings on HDD.
 

Black Hole

May contain traces of nut
Results of tuner test earlier in this thread.
Link? If the individual test available from the hidden service menu doesn't show a problem, I find it hard to believe there is a problem with one of the tuners. On the other hand: if it does, then you're buggered.
 

Black Hole

May contain traces of nut
You could have saved the reader some trouble:
Both tuners have Strength around 51% and Quality a solid 100% on all Transponders apart from 7460000Khz & 754000Khz, which report Strength 55-60% (higher) and Quality fluctuating wildly between 20% and 100%.
So you don't have a dodgy tuner then.
 
OP
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pADDYB

Member
You could have saved the reader some trouble:


So you don't have a dodgy tuner then.
Sorry, I really appreciate your help but I don't really know how to interpret these figures. The quality reading on those two transponders doesn't sound very healthy though? I've just looked again and it's down 5-10% most of the time.

To recap from earlier in this thread:
  • New aerial was installed, exactly the same results
  • TV Tuner still works fine
  • When box is booted up, HD channels play with glitches or not at all
  • While recording one channel, all HD channels are perfectly watchable
Additionally, to the last point, this works the other way around as well. I've found can record all HD channels perfectly if I'm watching another channel. What I can't do is watch/record two HD channels at the same time without one of them having a problem, or watch anything in HD if nothing is being recorded. This is where my theory about one of the tuners being faulty comes from.

If the tuner readings are as expected then could there be some other fault with the box that would cause this result? The quality of reception is continuing to deteriorate. Without using the trick above, I can only watch SD channels now. None of the HD channels are really watchable, they all have the nearly same amount of break up as BBC News HD had when I started this thread. BBC Four HD, BBC News HD etc now just come up with "The channel is scrambled or not available" most of the time.
 

MikeSh

Well-Known Member
BBC Four HD and News HD are on CH 55 & 56 (probably the 750 MHz channels you mention as being poor). These are the oddballs in the system and as the strength is good I'd suspect they are suffering interference from a nearby copy of the same channel/frequency.
 

Black Hole

May contain traces of nut
If the tuner readings are as expected then could there be some other fault with the box that would cause this result? The quality of reception is continuing to deteriorate. Without using the trick above, I can only watch SD channels now. None of the HD channels are really watchable, they all have the nearly same amount of break up as BBC News HD had when I started this thread. BBC Four HD, BBC News HD etc now just come up with "The channel is scrambled or not available" most of the time.
I appreciate what you are saying, but a specific test is provided which can monitor the performance of the two tuners individually, which must automatically exercise the control and data paths to each - and everything else is common so would affect both. I can't envisage any fault to reproduce what you are saying which would not show up on the hidden service test... which I think I said at the top of this thread.
 
OP
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pADDYB

Member
I appreciate what you are saying, but a specific test is provided which can monitor the performance of the two tuners individually, which must automatically exercise the control and data paths to each - and everything else is common so would affect both. I can't envisage any fault to reproduce what you are saying which would not show up on the hidden service test... which I think I said at the top of this thread.
It's a mystery then! Thanks for bearing with me and taking the time to help with this.

I'd suspect they are suffering interference from a nearby copy of the same channel/frequency.
Still interested in learning more about this, especially if it leads to a solution to the problem.

Other than that, sounds like a need to start thinking about getting a new PVR.
 

Trev

The Dumb One
And possibly have exactly the same problem if the problem is signal related as it seems to be.
The problem that you are having seems to be restricted to COMs 7 and 8, which have been 'screwed around' with lately (a techie term).
You may get some luck by pointing your aerial in a bit of a different direction to reduce the strength of the signal that is possibly giving you the grief.
 

MikeSh

Well-Known Member
Still interested in learning more about this, especially if it leads to a solution to the problem.
If two transmitters are using the same frequency then they will interfere with each other - in theory this could be constructive or destructive but in practice will usually cause problems. The normal solution is to ensure they are separated far enough apart and at a low enough power that a receiver will only pick up one of them. This is why, in general, different transmitter masts use frequencies not used by adjacent locations. (Those frequencies may be used again in more distant locations.)
COM 7 & COM 8 are currently a special case during 4G frequency clearance and use the same frequencies across the country. They are considered low priority or local muxes so are run at lower power than the main muxes and so are not likely to interfere with each other, in theory. The flipside is that they will only serve people fairly near or with 'powerful' aerials.

It seems probable to me that you are picking up a second COM 7/8 signal. If so then fixing it properly means a better aerial, which in practice probably means one that has greater directionality, which translates as being better able to reject the second, interfering, signal. These are usually the bigger ones - longer with more elements.
Trev is also alluding to this in his last sentence above - changing the direction of your current aerial might alter the balance between your desired transmitter and the interfering one enough for things to work. This will likely only help if the aerial is currently not aimed correctly at the required transmitter, so isn't getting the best power from it. Worth a try though.

That's my understanding of it anyway. There are others on here who can probably correct and/or add to what I've said.
 
OP
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pADDYB

Member
Thanks Trev & Mike
Sorry to labour this point, but I CAN get a perfect picture & sound on the Com 7 & 8 channels, but only when recording/watching another channel. Perhaps this gets rid of the interference between the two transmitters?

However the problem is no longer restricted to those channels, all HD channels are now having problems. TV tuner plays all channels ok.

I have already tried a new aerial:
https://hummy.tv/forum/members/paddyb.4680/
I spent a long time moving it a cm at a time to test directionality and it didn't make any difference and wasn't any better than the communal areal on the roof.

If this still sounds like an aerial issue then I can give another one a try if you could recommend one you think will do the trick? Note that I can only mount this on the side of my flat, not the roof, so I can only see Ridge Hill and Mendip (which is where all other houses have their pointing).
 

Trev

The Dumb One
Both Ridge Hill and Mendip have com 7 & 8 on CH 55 and 56. If they are both in more or less the same direction could very well have problems. When I said point the aerial in a different direction, I meant to give it a goodly hoik by about 20 degrees either way, not cm by cm.

Mendip is a bit west of due south of you and Ridge Hill is pretty well due west. Which way is your aerial pointing?
 
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OP
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pADDYB

Member
Both Ridge Hill and Mendip have com 7 & 8 on CH 55 and 56. If they are both in more or less the same direction could very well have problems. When I said point the aerial in a different direction, I meant to give it a goodly hoik by about 20 degrees either way, not cm by cm.
I meant that I moved it a cm at a time. I moved it by about 180 degrees in total.
 
OP
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pADDYB

Member
Actually, just checked now, roughly south west, but tried other directions in a 180 degree arch as well and there was no improvement. I can't point it in northwards as its on the side of the building, not the roof, but no other aerials are pointing that way.

Is it worth trying another type of aerial?
 
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