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Passing trains reboot my T2 watching HD

Discussion in 'HDR-FOX T2 Freeview Recorder' started by Gavarnos, Aug 15, 2012.

  1. Gavarnos

    Gavarnos New Member

    Newbie here, long time lurker with a post to announce I'm here I think!

    I've got rather a bit of a problem folks. I live alongside the busy southern railway London to Brighton line with the 750v DC third rail at Purley, Surrey, close to the northern points for the station approach and just up the line on the opposite side was the 1989 crash. Used to get terrible digital reception with break ups from passing trains until I installed a roof aerial on the chimney stack 3-4 years ago pointing at Crystal Palace and it's been great since, a perfect signal.

    That changed when I retired the 9300 and I installed the T2 two weeks ago. The nightmare has returned with a vengeance but watching HD channels exclusively and this time it reboots my box with some passing trains. My work as an IT consultant who fixes PC's and Mac thinks this is a serious problem for future disc corruption recording high def to the hard disc via Linux to an ext3 file system.

    Aside from the obvious realigning the aerial (I've seen a few birds using it as a perch recently) is there anything I can do to reduce the interference spike when the trains hit the third rails from 15-90 mph charged with thousands of amps before and after the points and reduce the chances of the Hummy rebooting itself?

    Any advice would be greatly appreciated!
     
  2. Ezra Pound

    Ezra Pound Well-Known Member

    As this didn't affect your 9300, It must either be that the HDR is more sensitive (which I don't think it is) or that the interference is much worse on the Crystal Palace Hi-Def channel only. As your channels are 22, 23, 25, 26, 28 and 30 for HD, this does place the Hi-Def channel at the high end Band A. I would say a Band A aerial would be better than a Wideband one, Also an aerial designed to cut out interference would be good, Don't be led down the path of just getting a bigger aerial as it will also pick up more of the unwanted 'noise'
     
  3. Black Hole

    Black Hole Felonius Gru

    Your reboots are not going to be a signal issue. Try a power conditioner between the mains socket and the Humax.

    The electricity supply companies have a duty of care though, ditto the rail (and any other) company regarding radiated interference - which could be due to an undetected fault in some equipment. if you can show your problems are induced from outside and not simply loss of signal due to temporary blocking, the authorities will take an interest.
     
  4. Gavarnos

    Gavarnos New Member

    Thanks, the standard channels are unaffected just like it was with the 9300, it seems to be only the DVB-T2 streams presumably with the much higher bit rate that seem to get upset. A Band A aerial sounds a good idea, I've had to manual retune because I was getting 800 channels from the Kenley sub-transmitter which I initially thought might have something to do with it at first.
     
  5. Gavarnos

    Gavarnos New Member

    When I did get the initial problem 3-4 years ago I ruled mains out though I will dig a filter out to double check again (also used a UPS last time too!) - its the trains passing on and off the third rail dropping and picking up the 20000amp DC current before and after the points causes the signal to break up.
     
  6. Ezra Pound

    Ezra Pound Well-Known Member

    Depending on the signal strength of Kenley sub-transmitter (Only 28 Watts) it might be worth trying the Hi-Def Mux. from there instead of crystal palace, I don't think it's the higher bit rate on the HD Mux. but it could be that only CH30 (546MHz) is being affected and that the Kenley HD CH50 (706MHz) might fare better against the interference. I do agree with BH that the rail company should be the ones fixing this problem, if you had a spark transmitter in your back garden the authorites would down on you like a ton of bricks
     
  7. grahamlthompson

    grahamlthompson Well-Known Member

    If you haven't already try a log-periodic aerial wired with sat grade wf100 cable.
     
  8. Black Hole

    Black Hole Felonius Gru

    ...but signal break-up should not cause reboots.
     
  9. xyz321

    xyz321 Well-Known Member

    Agreed but I have seen several reboots when severe picture break up occurs. In my case it was just a weak signal which has improved since DSO.

    I have also seen some of the "blockiness" become frozen on top of the picture. This would remain even when viewing the menu system or a previously recorded programme. The only way to remove it would be to reboot the Humax.
     
  10. Black Hole

    Black Hole Felonius Gru

    OK, fair enough then.
     
  11. Gavarnos

    Gavarnos New Member

    I wish it shouldn't but when it breaks up really badly it does exactly that and only on HD. Tried a bog standard mains surge protector which improved it marginally but rebooting only less often. The UPS i used lead acid cells are zeroed so I can't test that method until i borrow another. I've ordered a Russ Andrews supercube for the mains socket and a shielded cable with ferrite cores and sealed male bellings from wall plate to STB. My Hummy is on a wall bracket and the rear of the unit is exposed to the back door window overlooking the line where you can clearly see the collectors on the carriages spark when crossing the points, many of which make the spark of an arc welder seem tiny by comparison.

    If that lot doesn't work I'll move onto trying other cures..
     
  12. Black Hole

    Black Hole Felonius Gru

    Considering xyz's comments about signal degradation causing reboots (which looks like bad design or poor testing in the Humax), I take back my comments about the power supply.

    This is of no help to you, but having served some time in standards compliance I question the Electromagnetic Susceptibility testing Humax has done for CE marking (unless you have an atypical unit). If the unit is standards compliant then clearly the railway track is not - but I don't know whether there is a specific exemption for them (other than historical - predating standards compliance requirements).
     
  13. Gavarnos

    Gavarnos New Member

    I'm curious to think it may also be related to both the power supply and the rf spike, our substation supply is less than 100 yards away alongside the railway line. 5-6 years ago the track supply used to be 8-10k amps but they almost doubled the power for the newer fleets of longer and air conditioned rolling stock.

    Alongside getting a ups, filters and cables a good friend who builds UHF/VHF transmitters (and has had plenty of experience of CE) is going to bring his extremely expensive Rhode & Schwarz spectrum analyser around to see what turns up. He suspects the spikes are wideband and will vary according to how bad the track alignment is at the time and the collector alignments on each train. He also has a shielded box for 19u racks which will fit the humax inside plus I have some Tempest spec mu-metal strips I've kept for over 15 years cos I thought one day it might come in handy ;-)
     
  14. Black Hole

    Black Hole Felonius Gru

    You know where I'm coming from then. Tempest? One used to be taken out and shot for even mentioning its existence (but I think the rules have relaxed now).
     
  15. Ezra Pound

    Ezra Pound Well-Known Member

    I would watch out for the Humax over heating if placed inside an shielded box
     
  16. Gavarnos

    Gavarnos New Member

    Indeed! Thinking about it I reckon that's the first time I've ever mentioned that word in conjunction with the alloy on the Internet ever. All i will say is thinking back I'm still amazed at the designs it was used for and even more staggered at just how 'elaborate' were the places they lived. We both can't unsign our signatures on that piece of paper so let's stick to the Hummy and we'll both be fine ;-)
     
  17. Gavarnos

    Gavarnos New Member

    I agree, but for 10-20 minutes while the trains rattle past it'll be fine!
     
  18. Ezra Pound

    Ezra Pound Well-Known Member

    fair enough, Dont forget your copper tape :)
     
  19. Black Hole

    Black Hole Felonius Gru

    Well, I don't know what you were talking about, but I was talking about a play by The Bard of Stratford. What's this Hummy thing?