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Possible reasons for DVB T2 Problems?

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    Minstrel SE

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    I dont know if this is the right section to post in but I wondered if anybody can shed some light on my DVB T2 PSB3 reception problems?

    Some background is that after initial weeks of intermittent problems it worked fine for months through the HDR 2000T

    Its a landlords amplified aerial system and he doesnt appear to have done any work on it. The aerial on the roof looks suitably fancy to cope.

    Recently I have been back to intermittent problems or no signal at all. It can work for an evening and then not be working at say 2am. Sometimes after an initial stutter for a few seconds it works fine for hours

    Sometimes it stutters so badly I have to give up, then it might work ok the next day. It doesnt pixelate...it stutters than goes to a black screen...weak signal marker.

    Sometimes there is no signal at all on channel 54.

    I have complained to the Winter hill people over reports of maintenance but why does it intermittently work and they say now thats its not the transmitter. Its not mobile phone mast interference and its not hdmi cable interference

    I know that the DVB T2 is a higher data transmission rate or something.

    Any thoughts please? Is it likely to be the box, the aerial?...why did it work perfectly for months? I have considered neighbour interference, computers unshielded wall plates but nothing adds up.

    I suppose I need another box to compare. I did try a Huawei(now given away) and that seemed to pick up the signal but had its own problems of the picture going high brightness after 6 seconds. I wonder if the aerial system is just badly amplified.

    I think I need a backup globe aerial or something to test it. why did it work fine for months? If the aerial is incapable, misaligned or the amplifier faulty how does it work somtimes but not others?.

    If the Humax box is faulty how did it work perfectly for months then go intermittent again

    Its driving me mad this...why is it just DVB T2 BBC1 HD etc on that group. A TV engineer is expensive

    Just having a rant
    Best wishes to everyone on the forum

    | Tue 4 Jul 2017 13:55:24 #1 |
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    Martin Liddle

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    Minstrel SE - 48 minutes ago  » 
    I dont know if this is the right section to post in but I wondered if anybody can shed some light on my DVB T2 PSB3 reception problems?

    Could you tell us what the signal strength and quality is (as reported by the Humax) when the box is showing a channel from PSB3?

    | Tue 4 Jul 2017 14:48:35 #2 |
  3. FenderBender

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    Minstrel SE - 3 hours ago  » 
    Any thoughts please? Is it likely to be the box, the aerial?...why did it work perfectly for months? I have considered neighbour interference, computers unshielded wall plates but nothing adds up.

    We have an HDR Fox T2. We're located at the southern fringe of Winter Hill reception, and for years we had perfect reception on SD and HD. Around March this year we started losing BBC SD channels, and other SD channels were pixellating frequently. HD was almost unaffected but we did have slight interference on occasions. I had originally assumed it was due to the weather, as we have had it quite dry for some time. But when it was still going on in June I decided to check out our installation. (Incidentally, we have a separate Samsung TV plugged directly into the amp, and this has been unable to pick up any channels at all.)

    We have a dual-amp setup, in that a single in line amp is installed in the loft next to an 8-way splitter amp with a gain control. We also have two aerials pointing to different transmitters, so I have an aerial combiner feeding into the amps. The combiner is a high pass/low pass filter, so that one side receives channels 21-40 and the other 40-60(+). I initially turned the gain on the splitter up to max, although it wasn't far off max before I started. This appeared to make no difference.

    I made biggest difference by removing the Winter Hill aerial from the combiner and connecting it directly to the amp. Suddenly we now have 70-75% signal on all MUX's and 100% quality - no pixellation.

    While this is good for me, it doesn't answer the question why this started happening suddenly earlier this year. There seemed to be a sudden drop in power on some MUX's, especially the BBC SD ones, causing quality on those MUX's to fluctuate between 25 and 75%.

    I checked my aerial the other day. We have a high gain 52 element aerial exactly like this one, and I noticed last weekend that half of the first element is missing. I don't know how much of an effect this has on the reception, but maybe an aerial expert could give me a clue.

    At the moment it is all working fine on all channels, but I too would like to know if something has changed on Winter Hill.

    I called an aerial installer a couple of weeks ago who said they will come out and analyse our installation at no cost. They would only charge if we agreed to go ahead with any work they suggested. Perhaps an aerial installer near you will offer the same service.

    | Tue 4 Jul 2017 17:41:52 #3 |
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    Minstrel SE

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    Martin Liddle - 2 days ago  » 

    Minstrel SE - 48 minutes ago  » 
    I dont know if this is the right section to post in but I wondered if anybody can shed some light on my DVB T2 PSB3 reception problems?

    Could you tell us what the signal strength and quality is (as reported by the Humax) when the box is showing a channel from PSB3?

    Yes its at 73% strength and 100% quality when working. It sort of fluctuates between 72 and 73 but can drop out intermittently to zero when its giving problems.

    Sometimes when I tune in its all at zero but it was working last night after some initial stuttering. It seems to be working at the moment but it all went wrong a couple of months ago after working fine for months.

    | Thu 6 Jul 2017 19:23:58 #4 |
  5. grahamlthompson

    grahamlthompson

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    Minstrel SE - 22 minutes ago  » 

    Martin Liddle - 2 days ago  » 

    Minstrel SE - 48 minutes ago  » 
    I dont know if this is the right section to post in but I wondered if anybody can shed some light on my DVB T2 PSB3 reception problems?

    Could you tell us what the signal strength and quality is (as reported by the Humax) when the box is showing a channel from PSB3?

    Yes its at 73% strength and 100% quality when working. It sort of fluctuates between 72 and 73 but can drop out intermittently to zero when its giving problems.
    Sometimes when I tune in its all at zero but it was working last night after some initial stuttering. It seems to be working at the moment but it all went wrong a couple of months ago after working fine for months.

    At a guess you have overamplified the signal to create signal clipping in the tuner front end or simply have too high a gain aerial for your location.

    Signal clipping can actually reduce the indicated signal level because of distortion of the UHF carrier wave.

    Try attenuating the signal from the aerial producing the problems. With most kit a stable signal level of around 60% should avoid the issue.

    | Thu 6 Jul 2017 19:54:10 #5 |
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    pmiller056

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    It may be worth checking that the aerial has clear line of sight to the transmitter. My freeview aerial looks through some growing trees at the transmitter. Over the last few years the signal has got worse during the summer as the trees get higher. There is no usable signal on some muxes if the growing foliage is really wet. Once the trees dry a bit, everything is good. In winter things are better with reduced foliage on the trees. Raising the aerial a few years ago helped, but I've now moved to freesat.

    | Sat 8 Jul 2017 19:02:13 #6 |
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    Minstrel SE

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    Yes some good points but the aerial is effctively four or five stories high but we have some very tall old beech and chestnut trees this side. Dont think the aerial is pointing at them though.

    Whats hard to understand is that is was working perfectly for months and its working now.

    This is why I cant understand if its aerial amplification attenuation problems because it just wouldnt have ever worked for long periods of time

    Im thinking that they have been messing around with transmission standards and relay masts and something just isnt right.

    Again though whay would it work perfectly for months, then days at a time if it was an intermittent fault with equipment here.

    Interesting its just DVB T2 and no other groups are affected. I think that may be my biggest clue to work on. I had the Humax 5V antenna power off so Im switching that on now

    Best wishes to everyone on the forum

    | Tue 11 Jul 2017 10:53:31 #7 |
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    fedman1

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    Your problem may be due to atmospheric signal propogation changes caused by the current weather conditions. In the days of analogue transmisson it would show itself as patterning on the wanted picture, with digital it can block the wanted signal completly. Also it can be very frequency dependent affecting one mux while leaving others untouched. Under these conditions the use of an aerial amplifier will only make matters worse.

    | Tue 11 Jul 2017 11:29:29 #8 |
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    Minstrel SE

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    Yes something is going on as channel 26 which has BBC Parliament (not that I watch that) etc on it was down to only 10% quality yesterday and 48% signal strength up to 80% quality later on.

    So I get a range of signal strengths from 48% to 87%

    Until I have my own aerial system and another comparison box, I wont know for sure

    | Wed 12 Jul 2017 15:58:24 #9 |
  10. grahamlthompson

    grahamlthompson

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    Minstrel SE - 1 day ago  » 
    Yes some good points but the aerial is effctively four or five stories high but we have some very tall old beech and chestnut trees this side. Dont think the aerial is pointing at them though.
    Whats hard to understand is that is was working perfectly for months and its working now.
    This is why I cant understand if its aerial amplification attenuation problems because it just wouldnt have ever worked for long periods of time
    Im thinking that they have been messing around with transmission standards and relay masts and something just isnt right.
    Again though whay would it work perfectly for months, then days at a time if it was an intermittent fault with equipment here.
    Interesting its just DVB T2 and no other groups are affected. I think that may be my biggest clue to work on. I had the Humax 5V antenna power off so Im switching that on now
    Best wishes to everyone on the forum

    Without any sort of amplifier in the aerial connections why on earth did you turn on this option ? You are lucky most aerial systems are a short circuit to DC power. Fortunately Humax boxes are protected by DC current limiting protection.

    Nothing has changed transmitter wise. What may have happened is someone else may have complained about a weak signal somewhere else. They may have increased the level, as a result causing issues for you. Have you tried attenuating the signal ?

    | Wed 12 Jul 2017 20:15:59 #10 |

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