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Dropouts in sound and video on live or recorded TV

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    jacklx

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    Back in the days of analogue here in the Mendip area the transmission frequencies were in the upper range, I don't recall which bands but I know that the aerials on people's chimneys had small dipoles, directors etc. Now we are at the other end of the spectrum. There are still a lot of these 'old' aerials in use but I'm only aware of one person who needed to upgrade. She used a relay station (Hutton) which only transmitted two muxes plus an HD mux but after the last retune the frequencies changed to the 'bottom' of the spectrum so she could no longer receive BBC and ITV West from the relay station. Despite her aerial being vertically polarised she was able to pick up all SD stuff from Wenvoe, but this isn't much use unless you're happy to watch Welsh news. I had to use manual tuning for both the relay station and Wenvoe for the muxes which are the same throughout England. During the last retuning I noticed one of her neighbours had a new broadband aerial on the chimney pointing towards Mendip, despite Bleadon Hill being in the way. I called on the people who assured me that they were able to watch everything from Mendip so now the old aerial pointing at Hutton has been replaced. Sorry this is such a long story but it leads me up to a little 'muddying of the waters'. Might the adjacent transmissions from Wenvoe, nothing in the way apart from the Bristol Channel, be interfering with the transmissions from Mendip and causing the glitches???

    | Wed 21 Jul 2021 15:18:39 #11 |
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    jacklx

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    An addition; reading all the previous posts I'm assuming, perhaps wrongly, that the glitches are only occurring with HD broadcasts. Has anyone seen glitches on SD recordings?

    | Wed 21 Jul 2021 15:30:36 #12 |
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    Dan_in_stoke

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    Not sure if this is related but I get frequent dropouts from certain channels after 15-30minutes of watching.
    Channels like Yesterday, 5Star, Pick, Blaze on signal channels 42, 44, 47. (Are these what you call muxes ?)
    On first start up they are signal 100% quality 100%...then after 15-30 min the quantity drops and fluctuates between 40 - 70% meaning watching is frustrating at best and un-watchable at worst.

    For example I was viewing Fifth Element tonight on 5Star, for the first 30 min fine...now it’s impossible to watch.

    Other channels, bbc, itv, c4, HD channels are all fine and remain fine.

    Not sure if it is a box issue or aerial issue. I have reported it to support and waiting to here back.

    | Wed 21 Jul 2021 22:18:33 #13 |
  4. Luke

    Luke

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    Dan_in_stoke - 39 mins ago  » 
    the quantity drops and fluctuates between 40 - 70% meaning watching is frustrating at best and un-watchable at worst.

    That can be a symptom of over loading the signal strength.

    Dan_in_stoke - 39 mins ago  » 

    signal 100%

    Different models and even different units can vary by what they mean by 100% but that is at the top end of what you would hope that the recorder can cope with. It probably only displays up to 100% and so if its stronger will still show 100%.
    If you are using a signal amplifier then try and remove it. Otherwise try a cheap variable attenuator.

    | Wed 21 Jul 2021 23:08:22 #14 |
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    jacklx

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    First I'll answer a question I came up with earlier. Yes I have seen a glitch on a SD recording. Not as obtrusive as the ones seen on HD, a dark horizontal line from side to side. It IS recorded and replayable as are the HD glitches. Perhaps I should give up on HD, but not until I can see if the repositionong of my recorder has improved matters.
    But now in answer to Dan_in_stoke. It looks as if the numbers, 42,44 and 47 do refer to the muxes.
    https://www.freeview.co.uk/corporate/platform-management/channel-listings-industry-professionals
    This page from the Freeview website lists all programmes and indicates which mux is associated with each programme, e.g Yesterday (programme 26) is broadcast on ARQB mux in UK except the Channel Islands.
    https://www.freeview.co.uk/help/manual-retune
    This is also from the Freeview website and if you scroll to where it says
    'Detailed transmitter information' and click it. Enter your postcode and house number which then reveals another page which gives loads of useful information such as your local transmitters and lower down the page details of which muxes are used. I've tried a screenshot which doesn't work. This might
    https://www.dropbox.com/s/0fz0yoxdjlly2p8/Untitled%202.odt?dl=0
    it shows what I pick up from the Mendip transmitter. The mux numbers, 32,33,34,35 etc. are the numbers one needs to use if manual tuning is necessary.
    But this doesn't address your problems with programmes such as Yesterday on ARQB. 5Star is broadcast on the SDN mux. The problem may be aerial related but the information contained on the page showing which muxes are used in your area also tells you what power levels sre anticipated, another 'traffic light' system, green for good, red for bad reeption.
    I'll now post this to see if the links work.

    | Thu 22 Jul 2021 9:13:02 #15 |
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    fedman1

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    Gizmologist - 22 hours ago  » 
    Removal of the right-angled HDMI adapter has virtually resolved the original dropout problem - hence the delay in posting this as the problem has become much less frequent so getting examples has been difficult. HDMI has gone through several generations from its initial incarnation, and has become considerably more echnically demanding. I know from another incompatibility a while back that when HDMI is attached/first used it negotiates to establish whether the spec of each end, and all interconnects, are up to scratch. What I haven't been able to find is a clear description of whether the negotiation is only carried out on first connection or initiated on every use. Does anyone have a link to a good technical description? It may be that when changing around the HDMI cables on my new TV I need to force both ends to 'forget' and renegotiate.
    Sorry for the long post, but I wanted to try to ensure that what had been one issue is clear to people trying to solve what may be a different issue.
    All thoughts gratefully received!

    I cannot give a link for full HDMI spec, but from my limited experience a "handshake" is made between source and destination each time a connection is made i.e. either during power up, or when a cable is inserted.
    73's

    | Thu 22 Jul 2021 12:09:00 #16 |
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    Dan_in_stoke

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    jacklx - 12 hours ago  » 
    First I'll answer a question I came up with earlier. Yes I have seen a glitch on a SD recording. Not as obtrusive as the ones seen on HD, a dark horizontal line from side to side. It IS recorded and replayable as are the HD glitches. Perhaps I should give up on HD, but not until I can see if the repositionong of my recorder has improved matters.
    But now in answer to Dan_in_stoke. It looks as if the numbers, 42,44 and 47 do refer to the muxes.
    https://www.freeview.co.uk/corporate/platform-management/channel-listings-industry-professionals
    This page from the Freeview website lists all programmes and indicates which mux is associated with each programme, e.g Yesterday (programme 26) is broadcast on ARQB mux in UK except the Channel Islands.
    https://www.freeview.co.uk/help/manual-retune
    This is also from the Freeview website and if you scroll to where it says
    'Detailed transmitter information' and click it. Enter your postcode and house number which then reveals another page which gives loads of useful information such as your local transmitters and lower down the page details of which muxes are used. I've tried a screenshot which doesn't work. This might
    https://www.dropbox.com/s/0fz0yoxdjlly2p8/Untitled%202.odt?dl=0
    it shows what I pick up from the Mendip transmitter. The mux numbers, 32,33,34,35 etc. are the numbers one needs to use if manual tuning is necessary.
    But this doesn't address your problems with programmes such as Yesterday on ARQB. 5Star is broadcast on the SDN mux. The problem may be aerial related but the information contained on the page showing which muxes are used in your area also tells you what power levels sre anticipated, another 'traffic light' system, green for good, red for bad reeption.
    I'll now post this to see if the links work.

    Thanks Jack.
    Had a look at what you put.
    Muxs 42, 44, 47 appear to be coming from the Wrekin. Not sure if my aerial is pointed more towards Fenton. I've got an variable attenuator on the way to try, then its a call to an aerial engineer if that doesn't solve it.

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    | Thu 22 Jul 2021 21:25:11 #17 |
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    Bjwgorman

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    My Aura box has developed a new issue similar to this. It now just blacks out for a couple of seconds and then comes back on. The sound tends to stay on but not the picture. This is on both live and recorded.

    | Mon 26 Jul 2021 21:29:59 #18 |
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    jacklx

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    More from me, first for gizmologist who pointed out that his glitches do not get recorded. From this, and what he has said about the HDMI adaptor, I infer that his problem is confined to the HDMI connection between recorder and TV. Perhaps an alternate HDMI socket on the TV might be tried? Those of us who find the glitches are recorded are in a different situation. The glitches might be a problem with the transmitter (unlikely) but more likely to be with the aerial or the electronics within the recorder which demultiplexes the signal prior to it being recorded and sent to the TV. I think it helps to see if the problem is more pronounced with HD transmissions, as these are more complex then the glitches may appear more serious. I've already discovered a glitch on SD is easier to live with.
    Temperature could be a factor either with reception from the transmitter or overheating of the recorder. Since repositioning my recorder I haven't been aware of any glitches.
    Ben in stoke could look elsewhere on the website dealing with muxes etc as entering one's postcode details brings up where all the local transmitters are along with distance and bearing and details of what type of aerial should be used and whether signals are horizontally (H) or vertically (V) polarised. Here (Mendip area) vertcal polarisation is only used for relay stations. It always helps to see how neighbours aerials appear and even talk to neighbours to see how things are. It is not unknown for a property to have an aerial which is no longer used as the user has installed Sky and no longer uses terrestrial TV but doesn't want to go to the bother of having the old aerial removed.
    Bjwgorman has a different symptom, picture blacks out, sound OK and the problem is recorded. Might this be HD, SD or both? points to the recorder or aerial. I suppose it helps if one tries watching the TV in isolation, if glitches still occur it points to aerial, not the recorder. I record everything we watch so we can skip through adverts and boring items on the news, half hour news programme invaribly tekes 5 minutes to watch, so I have to put up with glitches.

    | Tue 27 Jul 2021 12:19:47 #19 |
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    havenview

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    There are numerous posts on several forums with regard to some poeple having issues with signal levels for the Humax Aura

    There seems a strong voice from some that this is an HDMI issue but HDMI faults manifest very different traits than signal issues and I believe now I have found proof that these issues are FIRMWARE related and I would like to invite members to try out some tests to add weight to my findings

    My signal issues manifest themselves only on certain muxes and they are "reliably faulty" in that I can tune to a channel and within a few minutes be guaranteed of viewing picture block freezes, audio pops and several seconds of I/B/P frame blocking.

    My antenna system is good and I have checked using 2 aerials and confirmed good signal AND acceptable levels to muliple other boxes so I was sure this was NOT a signal related issue. I experience good level and quality readings from the built in signal testfor some muxes but on the faulty ones the quality jumps from 100% down to as low as 40% in an erratic manner

    I also noted that there seemed to be an improvement when the box was restarted but only for a limited period - indeed other users have also posted on this too

    Then it finally clicked - the issue happens as a consequence of CHANGING channel - the testing procedure is this

    1. Tune to a faulty channel and observe the picture/sound break up

    2. Issue a reboot - I use the freeview button and cursor all the way over to the right to the power icon and choose restart

    3. Wait for the box to restart - the previous faulty channel should be the default tuned channel - DO NOT CHANGE CHANNEL

    4. Observe if there is any break up - in my case at this point the picture and sound stability has always been A1

    5. Now change channel to a different mux (an easy bet would be to go between an SD and an HD channel) and then return to the original suspect channel

    6. For me the break up and distortion starts happening almost immediately

    7. Reboot and all comes good

    In my system the worst channels always seem to be on COM5 (Winter Hill) so I've been checking using Sky Arts on channel 11. I tuned and rebooted to that Yesterday morning and left it alone and not changed channel. It has been rock solid every time I have checked - even with other channels recording. I have just changed channels now and straight away I get the picture and sound break up return

    I would be interested if other users who have experienced this issue could also try this as a means of wider testing

    | Wed 4 Aug 2021 21:46:15 #20 |

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