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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions. |
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I was talking to somebody a week or so back who swears their freeview goes
blacky and stutters whenever a plane from Heathrow goes over. Now in the good old analogue days you could detect aircraft flutter quite easily, how would you go about it on a digital system. I did not rise to the bait of suggesting I go around as to be honest there would be little I could do. We are after all in a very strong signal area here, and I'd have thought it most unlikely that a properly installed aerial would have this problem, which leaves either paranoia or a faulty installation. Brian -- ----- - This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... Blind user, so no pictures please! |
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On Sunday, 11 March 2018 11:07:04 UTC, Brian Gaff wrote:
I was talking to somebody a week or so back who swears their freeview goes blacky and stutters whenever a plane from Heathrow goes over. In Yorkshire. Now in the good old analogue days you could detect aircraft flutter quite easily, how would you go about it on a digital system. I did not rise to the bait of suggesting I go around as to be honest there would be little I could do. We are after all in a very strong signal area here, and I'd have thought it most unlikely that a properly installed aerial would have this problem, which leaves either paranoia or a faulty installation. Brian Perhaps s/he has Freesat and is very close to the airport. Can't see a mechanism otherwise. |
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In article , R.
Mark Clayton wrote: We are after all in a very strong signal area here, and I'd have thought it most unlikely that a properly installed aerial would have this problem, which leaves either paranoia or a faulty installation. Brian Perhaps s/he has Freesat and is very close to the airport. Can't see a mechanism otherwise. RX being overloaded by some signals from the plane adding to the "strong" ones from Freeview? i.e. matter of an RX that accepts and is overloaded by out of band input at a high power level? -- Please use the address on the audiomisc page if you wish to email me. Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html Audio Misc http://www.audiomisc.co.uk/index.html |
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On Sunday, 11 March 2018 13:11:25 UTC, Jim Lesurf wrote:
In article , R. Mark Clayton wrote: We are after all in a very strong signal area here, and I'd have thought it most unlikely that a properly installed aerial would have this problem, which leaves either paranoia or a faulty installation. Brian Perhaps s/he has Freesat and is very close to the airport. Can't see a mechanism otherwise. RX being overloaded by some signals from the plane adding to the "strong" ones from Freeview? i.e. matter of an RX that accepts and is overloaded by out of band input at a high power level? Faintly possible, but AFAIK the only big output from a plane is ATC in AM VHF [for now]. |
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Brian Gaff wrote:
I was talking to somebody a week or so back who swears their freeview goes blacky and stutters whenever a plane from Heathrow goes over. Now in the good old analogue days you could detect aircraft flutter quite easily, how would you go about it on a digital system. I did not rise to the bait of suggesting I go around as to be honest there would be little I could do. We certainly got that effect when watching FreeView on our boat moored very close to London City Airport. When I say close I mean *close*, the runway lights continued through the marina. I guess we probably didn't have a particularly strong signal but we did have a directional aerial outside pointing in the right direction (except when the wind blew it wonky). The effect was usually breaking up and then loss of picture (and sound) for a few seconds when planes went over. We are after all in a very strong signal area here, and I'd have thought it most unlikely that a properly installed aerial would have this problem, which leaves either paranoia or a faulty installation. Brian -- Chris Green · |
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On Sun, 11 Mar 2018 06:22:22 -0700 (PDT), "R. Mark Clayton"
wrote: On Sunday, 11 March 2018 13:11:25 UTC, Jim Lesurf wrote: In article , R. Mark Clayton wrote: We are after all in a very strong signal area here, and I'd have thought it most unlikely that a properly installed aerial would have this problem, which leaves either paranoia or a faulty installation. Brian Perhaps s/he has Freesat and is very close to the airport. Can't see a mechanism otherwise. RX being overloaded by some signals from the plane adding to the "strong" ones from Freeview? i.e. matter of an RX that accepts and is overloaded by out of band input at a high power level? Faintly possible, but AFAIK the only big output from a plane is ATC in AM VHF [for now]. Is there any possibility of Freeview sugnals being reflected off the plane at sufficient strength to interfere with the direct signal? I suppose that would need a badly positioned aerial so that its reception of the direct signal was poor. -- Peter Duncanson (in uk.tech.digital-tv) |
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This is Kingston upon Thames.
However, I wondered if maybe its possible to somehow tune into the channel on a scanner and listen for the usual flutter on the signal as its really just multipath cancelling or adding to the signal as the plane reflection moves. Brian -- From the Sofa of Brian Gaff Reply address is active Remember, if you don't like where I post or what I say, you don't have to read my posts! :-) "R. Mark Clayton" wrote in message ... On Sunday, 11 March 2018 11:07:04 UTC, Brian Gaff wrote: I was talking to somebody a week or so back who swears their freeview goes blacky and stutters whenever a plane from Heathrow goes over. In Yorkshire. Now in the good old analogue days you could detect aircraft flutter quite easily, how would you go about it on a digital system. I did not rise to the bait of suggesting I go around as to be honest there would be little I could do. We are after all in a very strong signal area here, and I'd have thought it most unlikely that a properly installed aerial would have this problem, which leaves either paranoia or a faulty installation. Brian Perhaps s/he has Freesat and is very close to the airport. Can't see a mechanism otherwise. |
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Brian-Gaff wrote:
This is Kingston upon Thames. # On pirate satellite ... |
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On 11/03/2018 11:07, Brian Gaff wrote:
I was talking to somebody a week or so back who swears their freeview goes blacky and stutters whenever a plane from Heathrow goes over. Now in the good old analogue days you could detect aircraft flutter quite easily, how would you go about it on a digital system. I did not rise to the bait of suggesting I go around as to be honest there would be little I could do. We are after all in a very strong signal area here, and I'd have thought it most unlikely that a properly installed aerial would have this problem, which leaves either paranoia or a faulty installation. Brian Reflected signals from rapidly moving wind turbine blades cause cancellation and reinforcement effects that can put deep notches in a mux. The notch will move rapidly across the mux. This can confuse some TV sets, but not others. AGC inadequacies perhaps? The fault is most likely to be seen when the turbine is slightly to one side of the direct signal path, because in that case the receiving aerial's forward lobe will include the turbine. In the case of aeroplane reflections, a horizontally polarised TV aerial, especially a log periodic, will have a forward lobe that includes a lot of sky above the transmitter direction. A plane in that area, if flying fairly low, could well have a surface with the angle of incidence and reflection such that a strong signal might enter the TV aerial. I've never seen the fault though with digital TV, but I saw it lots of times in the analogue days. Going even further back in time it used to be a real bugger with BI TV. Bill |
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In article , Bill Wright
wrote: Reflected signals from rapidly moving wind turbine blades cause cancellation and reinforcement effects that can put deep notches in a mux. I was wondering about the doppler from the plane's velocity. But you remind me that the fan blades might also generate quite a lot of doppler on the reflections. But I've not worked out the velocity needed to shift each subcarrier by the difference in frequency between subcarriers. Jim -- Please use the address on the audiomisc page if you wish to email me. Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html Audio Misc http://www.audiomisc.co.uk/index.html |
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