SamsungTV<->HDMI<->Huawei YV, and UHF 55 (COM7)

meyou2meyou2 Member Posts: 39
I wonder if anyone else has seen anything like this....

I have a Samsung TV, UE39F5500, and on it I can get all the COM7 channels (55 UHF, 746MHz) absolutely fine, with the TV reporting Signal Strength and Signal Quality both at 100 (the max) and Bit Error Level at zero.............

..........until I turn on my YouView box, then Bit Error Level leaps to the max of 2000 and Signal Quality plummets to zero and, of course, watching becomes problematic.

I have three YV boxes, 2 DN372Ts and a DN360T (not all connected at the same time!) and after some experimentation I've found:

a) the same problem (and everything below too) happens with any/all of them
b) it only happens when the (a/any) YV box is connected to the TV by HDMI
c) it doesn't happen if the YV box is connected to the TV by SCART
d) it doesn't matter which HDMI socket(s) I use (the TV has 3), nor which cable (I have 2)
e) the problem is bi-directional!

Yes, having the YV box connected to the TV by HDMI causes the Signal Quality of the COM7 channels on the YV box to drop from watchable to zero too.

And here's the really weird bit: if I connect a YV box to the TV by SCART then the COM7 channels on the YV box are fine, but if I then connect a second YV box to the TV by HDMI then the Signal Quality of the COM7 channels on the first YV box (which is only connected by SCART) drops to zero!

(And it's not anything to do with the aerial connection, or ethernet for that matter, 'cos the same happens even if the second YV box is disconnected from everything else other than the HDMI cable and the power supply.)

This only happens for UHF 55 (COM7).  All other muxes are fine, and the problem doesn't happen with plugging in the only other HDMI device I have, my laptop, into the TV.

Given all the above, the only thing I could think of is that the Huawei boxes are radiating 746MHz from the HDMI cable, but nowhere near that frequency seems to be used by HDMI, from what I've read, and I've also tried disconnecting the HDMI cable from the TV and wrapping it around the aerial cable, but it's only when it's plugged into the TV the problem shows....

Anyone else seen anything like this?

Comments

  • John LJohn L Member, Super User Posts: 532 ✭✭
    Hi meyou2,
    Yes I have found same problem and mentioned it in a previous topic.
    Have you tried changing 1080p to 1080i on any other devices connected to TV.
    I know my Freesat when it boots up affects Youview signal. But is now better on Channel 107 BBC news HD when Freesat is on 1080i. Worth trying.
    So yes there must be interference somewhere in the Youview hardware coming from HDMI circuit. Not sure what Youview can do? It only seems to affect com7/8 channels.  My conclusion is that the TV has a stronger tuner /built-in amp to cope with problem. Hopefully when channels are changed again all will be improved. I can only guess that a lot of users aren't bothered/don't report it, either switch to SD channels or swap their equipment to an alternative Pvr such as Freeview or simply use TV's own tuner for watching problem channels. Not an ideal solution. John L

    Can't wait for the day when Youview get rid of the dreaded darkened banner when using fast forward/rewind recordings. 
  • VisionmanVisionman Member, Super User Posts: 9,744 ✭✭✭
    HDMI leads's can sometimes interfere with aerial lead signals. Are you using a shielded one? If not even a 99p one from a pound shop would be worth a try.
    I disagree with the disagree as is, as its a joke.
  • joneshjonesh Member, Super User Posts: 1,374 ✭✭✭
    The problem of RF interference from HDMI cables affecting aerial signals is well documented. It isn't Youview specific. The frequency of the radiation emitted is dependent on the frequency of the signal passing throught the cable, so a cable carrying a 1080i signal would radiate interference at a different frequency from one carrying 1080p. The amount of radiation emitted is dependent on the quality of the cable and the way that it is terminated.
    The problem can be minimised by using good quality, well terminated cables for both the HDMI and aerial connections, but there is no need to splash out on super-duper cables with gold plated connectors.
    It is good practice to keep HDMI and aerial cables away from each other as far as possible.
  • meyou2meyou2 Member Posts: 39
    Thanks folks :smile:

    Changing to 1080i seems to help on one DN372T, although not on the other.

    In regards to are they shielded cables, dunno :blush:   One has simply High Speed HDMI Cable with Ethernet on it (and I think I did get from a local cheapo shop), and the other has E306792 AWM 20276 30AWG and I think was supplied by TalkTalk.  Paradoxically, the first is the one attaching the box on which changing to 1080i helped.

    In regards to keeping HDMI and aerial cables away from each other, the sockets for all them on the TV are pretty close together, with one HDMI socket just an inch from the aerial socket (although, again, that's the one where changing to 1080i helped), but in any case, I will have a go at moving cables around, to see if that helps.... :smiley:
  • joneshjonesh Member, Super User Posts: 1,374 ✭✭✭
    An inch apart is better than nothing.
    Even good quality cables can be faulty.
    The frequency of the radiation emitted by a cable carrying 1080i is probably half that of 1080p, so if you are unlucky enough for one of them to interfere with your aerial signal, then the other might as well.
  • RoyRoy Member, Super User Posts: 15,630 ✭✭✭
    jonesh said:
    An inch apart is better than nothing.
    Even good quality cables can be faulty.
    The frequency of the radiation emitted by a cable carrying 1080i is probably half that of 1080p, so if you are unlucky enough for one of them to interfere with your aerial signal, then the other might as well.
    Yes, get a good one; cheapos are a false economy. But the Amazon Basics cables are plenty good enough; no need to spend more.

    Also worth trying the YouView box at 720p, at least as a test; if the cables are radiating interference, this will alter what and at what frequency this is.

    Cables close together at the box are no great problem; the thing to avoid is running the aerial cable and the HDMI cable parallel to one another, and close together, as can happen in ducting.
    I have a low opinion of people who press the Disagree button instead of engaging in reasoned debate. 
    I have an even lower opinion of YouView’s continued policy of letting such people hide behind the cloak of anonymity.
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