TV signal interference from passing busses

Discussion in 'Digital TV & Video Players & Recorders' started by Auric Mists, Oct 10, 2017.

  1. Auric Mists

    Auric Mists
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    Hi,

    TV signal interference from passing busses

    Recently, I have started experiencing break up of my TV signal.
    For a period of at least 30 seconds, sometimes much longer, the picture and sound are intermittent with the picture pixellating and disappearing completely.
    Also, the signal quality and strength jump about from 100% to 0% and back again.

    I have identified that this happens only when some busses pass on the main road that I live beside.
    The longer periods are when the busses stop at the bus stop outside my house.
    These busses have built in wi-fi for travellers which I think must be responsible for this interference.
    Although I don't know the exact technology they use, I suspect that these busses act as giant mobile phones.

    First I tried replacing my old aerial with a new Labgear LAB450T LTE800 ready aerial but this did not fix the issue.
    I tried pointing the aerial at a different transmitter but, again, no joy.
    I have tried putting an approved 4g filter in the aerial line but this has no noticeable effect.
    I am at my wits end with this one and would appreciate any help that anyone can give.

    Thanks in anticipation.
     
  2. JayCee

    JayCee
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    Wi-Fi on a passing or stationary bus has nothing to do with your signal loss.
    Location and local transmitter info here will help others to help you.
     
    Last edited: Oct 10, 2017
  3. Auric Mists

    Auric Mists
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    @JayCee Thanks for the reply.
    On your first point I challenge you to come and see for yourself what effect the busses have on my TV signal quality. It is consistent that the signal starts to break up approx. 15 secs before East Coast Busses service 106 and 107 pass by, and lasts until approx. 15 seconds after they pass by.

    I'm not saying that it definitely is their wi-fi and would welcome any alternative cause of this problem and, more importantly, possible solutions.

    I concur on your other point and offer the following additional information.

    I live just outside Dunbar in Scotland. GR 55°59'42"N 2°33'07"W
    The first transmitting mast I was pointing at was CraigKelly GR 56°4'17"N 3°14'1"W
    Craigkelly (Fife, Scotland) Full Freeview transmitter
    The second mast is Durris GR 56°59'59"N 2°23'30"W
    Durris (Aberdeenshire, Scotland) Full Freeview transmitter

    Thanks for any help.
     
  4. JayCee

    JayCee
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    I don’t doubt the bus is the cause of your signal breakup but it’s definitely not wi-fi that’s causing it. The bus is in the path of your signal...you need to improve your aerial system to prevent it. You may need to get a professional aerial rigger to check the orientation and signal strength to maximise it.
     
  5. pedro2000uk

    pedro2000uk
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    Could be cabling too, if a cable's become wet inside with water tracking down it & especially if it was aluminium, you could have almost un-shielded coax which could pick up any interference.

    It could be a fault on a bus's ignition, I've had satellite installations very near busy motorways etc.. where it's noticeable when certain vehicles passed it would show interference - mobile phones being the main suspect & maybe ignition interference but a good install/ good cabling & shielding if possible usually remedied it
     
  6. Auric Mists

    Auric Mists
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    There are many HGVs and other busses that pass on the same route and none of them cause this type of interference so I doubt that the bus is blocking the signal path.
    The signal starts to degrade when the bus is at an angle of close to 90° on the approach and similarly on exit (The main road is 10m from the house and the interference starts/stops when the bus is approx 200 metres away in either direction).
    I thought it may have been the bus tracking technology that is causing it but this also uses mobile phone technology to transmit the position to the tracker server.

    As mentioned, a new hi-tech aerial has been fitted, complete with new wiring, and this has not helped.
    I need to use a 4 way splitter to divert the signal into other rooms and I get the same issue whether this is in-circuit or not.
    The signal strength has been maximised and the aerial is pointing to within a few degrees of the transmitter.

    I used to know a great deal about TV signals when I was a TV engineer many years ago but have not kept up with it since moving into computers, so digital TV signal transmission technology is relatively alien to me.

    I surely will seek professional help but I want to exhaust all the other possibilities first (I like to understand why these issues exist and treat this as a learning curve).

    Thanks.
     
    Last edited: Oct 12, 2017
  7. grahamlthompson

    grahamlthompson
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    Diesels don't have ignition systems (ignition of the fuel is solely by compression). I doubt there is many petrol driven buses on the road anymore, other than vintage ones.
     
  8. pedro2000uk

    pedro2000uk
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    Yes.. I thought at the time wrong word to use. . Yes anything electrical.. injectors / alternator. . Could even be electric
     
  9. grahamlthompson

    grahamlthompson
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    I can't imagine that sort of kit generating anything in the UHF band. It would take a electric arc like a distributor or a faulty dynamo generating arcing on the commutator. A alternator delivers pure DC by way of slip rings to the field coils. There is no way that any arcing can occur. It has to be a either a high power source of UHF (possibly harmonics) or it's just physically blocking the transmitter signals.

    Can the OP confirm if VHF (DAB/FM) radio is similarly affected.

    Might be worth the OP talking to OFCOM with a view to getting them to investigate.
     
  10. JayCee

    JayCee
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    The OP has stated it also happens when HGV's pass the same spot.
     
  11. grahamlthompson

    grahamlthompson
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    EH :(

     
  12. pedro2000uk

    pedro2000uk
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    All good thoughts on the matter, I confess I'd expect general interference from engines long since dealt with and not like the old days when it was very obviously a passing vehicle, although I wouldn't rule anything out, we live in a noisy world and every noise can produce harmonics that are very difficult to map

    i did say the main suspect mobile phones, well when I've witnessed similar on installs near busy motorways etc. . I've pictured someone using one

    it's nice to track down & idemtify any source of interreference
    Interesting subject but usually not easy it's such a big subject
     
  13. grahamlthompson

    grahamlthompson
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    I remember a similar post some years ago but the problem was a electrified main line at the bottom of the garden. Arcing from the pantographs of passing trains blanked the signals. In that event if I remember correctly fitting a log periodic aerial solved it. log aerials have a good rejection of impulse generated noise. No guarantees, it might be worth the OP trying the same.
     
  14. pedro2000uk

    pedro2000uk
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    It might, in these circumstances, it's the sort of solution that can get a result. In satellite reception you can have an interference situation [either locally produced or satellite based harmonics/ bleed over or a combination of both ] & swapping to a less sensitive/ less amplified &/or more filtered lnb is an option on the same sort of lines. The Logs are usually lower gain & often used with amps but with the sort of power increase that took place during the switch over, chances are they won't need it in most circumstances.
     
  15. chillax

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    I live in East Lothian too and am getting exactly the same problem from Lothian/Borders buses. The bus stop is around 50 yards down the road from my house, and when the bus arrives at the stop, my tv signal goes all blocky, sound disappears and sometimes the screen goes totally black (signal lost comes up at that point). This continues until the bus has drove past the house
    Ariel is in loft, has been checked and is ok. Digi box is a Humax Youview box.
    It has to be something fitted to these buses! It can't be the size of the vehicle either, as it does the same thing whether a single deck bus or a double deck bus. Articulated trucks etc cause no problems at all, same with private bus/coaches.
    There was never any interference before buses started being fitted with WIFI so I still think this could possibly be the cause. I know LB also have hybrid buses, but they don't operate to the town where we live so only the diesel buses. Really fed up with it as we never had any problems before with the same tv set up as we have now, and buses then didn't cause any issues.
    I'm thinking of contacting LB as stating the problems we have with the buses. (On a side note, can people not live without their blooming smartphones/internet for the length of a bus ride! jeese, seems people are just addicted to them! Why a bus needs WIFI is beyond me!)

    Any advice would be welcome as I'm really fed up with the constant interference (bus passes here every 15 mins, but sometimes there's more than one bus at a time with just a few mins apart)

    Thanks in advance
     
  16. mike7

    mike7
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    I'd have a word with the bus company. We have had various systems tried locally which locate where buses are and report back to base, or show up on a display at the bus stops. They've never lasted long and I have not heard that they have caused interference.
     

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