• multipath

    From williamwright@21:1/5 to All on Wed Jan 5 18:09:24 2022
    https://www.instructables.com/HDTV-Multipath-Shield/

    I don't believe this is genuine, for a a number of reasons.

    Bill

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  • From R. Mark Clayton@21:1/5 to wrightsaerials@aol.com on Wed Jan 5 11:03:11 2022
    On Wednesday, 5 January 2022 at 18:09:26 UTC, wrightsaerials@aol.com wrote:
    https://www.instructables.com/HDTV-Multipath-Shield/

    I don't believe this is genuine, for a a number of reasons.

    Bill

    Multipath was certainly an issue for analog TV, and a paler shadow image would appear displaced horizontally in the picture.

    Not an issue AFAIK with terrestrial digital TV. You can get adjacent channel interference on satellite if you don't have your LNB aligned quite right.

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  • From Mark Carver@21:1/5 to R. Mark Clayton on Wed Jan 5 20:03:11 2022
    On 05/01/2022 19:03, R. Mark Clayton wrote:
    On Wednesday, 5 January 2022 at 18:09:26 UTC, wrightsaerials@aol.com wrote:
    https://www.instructables.com/HDTV-Multipath-Shield/

    I don't believe this is genuine, for a a number of reasons.

    Bill
    Multipath was certainly an issue for analog TV, and a paler shadow image would appear displaced horizontally in the picture.

    Not an issue AFAIK with terrestrial digital TV.
    It's certainly not an issue for DVB-T,  but ATSC  is a different kettle
    of fish.

    For starters, as the web page shows, it has a 'spot' pilot carrier, I
    need to read up on what purpose that serves  ?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From williamwright@21:1/5 to Mark Carver on Thu Jan 6 02:01:02 2022
    On 05/01/2022 20:03, Mark Carver wrote:
    On 05/01/2022 19:03, R. Mark Clayton wrote:
    On Wednesday, 5 January 2022 at 18:09:26 UTC, wrightsaerials@aol.com
    wrote:
    https://www.instructables.com/HDTV-Multipath-Shield/

    I don't believe this is genuine, for a a number of reasons.

    Bill
    Multipath was certainly an issue for analog TV, and a paler shadow
    image would appear displaced horizontally in the picture.

    Not an issue AFAIK with terrestrial digital TV.
    It's certainly not an issue for DVB-T,  but ATSC  is a different kettle
    of fish.

    For starters, as the web page shows, it has a 'spot' pilot carrier, I
    need to read up on what purpose that serves  ?


    Well anyway, here's why I think it's a made-up article.
    1. He says that the reflections are caused by "signal bouncing back and
    forth between the two buildings" that are either side of the signal
    path. Gibberish.
    1a. If he is suffering multipath it won't be from those buildings; it
    will be from buildings to the side and rear of his location, with the
    s/n ratio worsened by the foliage attenuation of the direct signal path.
    1b. His screening device couldn't possibly discriminate between a signal originating from between those buildings and a reflection coming from
    one or both of the buildings. The angle is too narrow.
    2. The screening box-thing is so close to the aerial that it encroaches severely on the aerial's capture area. It's about λ/2 but it needs to at
    least 2λ. It would de-tune the aerial and lower the gain severely. The
    same applies to the dustbin idea.

    My guess is he's done this in ignorance and found it didn't work so he's
    just made out it has.

    Bill

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From R. Mark Clayton@21:1/5 to wrightsaerials@aol.com on Thu Jan 6 07:11:36 2022
    On Thursday, 6 January 2022 at 02:01:05 UTC, wrightsaerials@aol.com wrote:
    On 05/01/2022 20:03, Mark Carver wrote:
    On 05/01/2022 19:03, R. Mark Clayton wrote:
    On Wednesday, 5 January 2022 at 18:09:26 UTC, wrights...@aol.com
    wrote:
    https://www.instructables.com/HDTV-Multipath-Shield/

    I don't believe this is genuine, for a a number of reasons.

    Bill
    Multipath was certainly an issue for analog TV, and a paler shadow
    image would appear displaced horizontally in the picture.

    Not an issue AFAIK with terrestrial digital TV.
    It's certainly not an issue for DVB-T, but ATSC is a different kettle
    of fish.

    For starters, as the web page shows, it has a 'spot' pilot carrier, I
    need to read up on what purpose that serves ?

    Well anyway, here's why I think it's a made-up article.
    1. He says that the reflections are caused by "signal bouncing back and forth between the two buildings" that are either side of the signal
    path. Gibberish.
    1a. If he is suffering multipath it won't be from those buildings; it
    will be from buildings to the side and rear of his location, with the
    s/n ratio worsened by the foliage attenuation of the direct signal path.
    1b. His screening device couldn't possibly discriminate between a signal originating from between those buildings and a reflection coming from
    one or both of the buildings. The angle is too narrow.
    2. The screening box-thing is so close to the aerial that it encroaches severely on the aerial's capture area. It's about λ/2 but it needs to at least 2λ. It would de-tune the aerial and lower the gain severely. The
    same applies to the dustbin idea.

    My guess is he's done this in ignorance and found it didn't work so he's just made out it has.

    Bill
    +1

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Brian Gregory@21:1/5 to williamwright on Thu Jan 6 15:55:03 2022
    On 06/01/2022 02:01, williamwright wrote:
    My guess is he's done this in ignorance and found it didn't work so he's
    just made out it has.

    One way it could have worked that I can think of is if the signal is too
    strong and this just works as a substitute for an attenuator.

    I guess his dustbin cantenna could work with a very simple antenna in
    the dustbin. The one in the dustbin does look like it's only two elements.

    --
    Brian Gregory (in England).

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  • From Brian Gaff (Sofa)@21:1/5 to All on Fri Jan 7 09:11:26 2022
    Just up the road from here is Tolworth Tower and there are places around there, at least in the analogue days, where reception had so many
    reflections it was impossible to watch it. I've not heard how it fares in
    the digital age.
    Brian

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    "R. Mark Clayton" <notyalckram@gmail.com> wrote in message news:2631d8fd-2e1b-4097-b4c5-8960a22ee954n@googlegroups.com...
    On Wednesday, 5 January 2022 at 18:09:26 UTC, wrightsaerials@aol.com
    wrote:
    https://www.instructables.com/HDTV-Multipath-Shield/

    I don't believe this is genuine, for a a number of reasons.

    Bill

    Multipath was certainly an issue for analog TV, and a paler shadow image would appear displaced horizontally in the picture.

    Not an issue AFAIK with terrestrial digital TV. You can get adjacent
    channel interference on satellite if you don't have your LNB aligned quite right.

    --- SoupGate-Win32 v1.05
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  • From Brian Gaff (Sofa)@21:1/5 to williamwright on Fri Jan 7 09:27:11 2022
    Like I say it can for extremely high frequencies, but in that case the
    aerial and its 'can' need to be designed as a unit, not just any thing will
    do, unless he has been very lucky in some way.
    I've seen mesh cages on the top of receiving stations to stop the
    interference from behind, but in no case do they contain the aerial.
    Brian

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    This newsgroup posting comes to you directly from...
    The Sofa of Brian Gaff...
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    Blind user, so no pictures please
    Note this Signature is meaningless.!
    "williamwright" <wrightsaerials@f2s.com> wrote in message news:j3n0quFisnmU1@mid.individual.net...
    On 05/01/2022 20:03, Mark Carver wrote:
    On 05/01/2022 19:03, R. Mark Clayton wrote:
    On Wednesday, 5 January 2022 at 18:09:26 UTC, wrightsaerials@aol.com
    wrote:
    https://www.instructables.com/HDTV-Multipath-Shield/

    I don't believe this is genuine, for a a number of reasons.

    Bill
    Multipath was certainly an issue for analog TV, and a paler shadow image >>> would appear displaced horizontally in the picture.

    Not an issue AFAIK with terrestrial digital TV.
    It's certainly not an issue for DVB-T, but ATSC is a different kettle of
    fish.

    For starters, as the web page shows, it has a 'spot' pilot carrier, I
    need to read up on what purpose that serves ?


    Well anyway, here's why I think it's a made-up article.
    1. He says that the reflections are caused by "signal bouncing back and
    forth between the two buildings" that are either side of the signal path. Gibberish.
    1a. If he is suffering multipath it won't be from those buildings; it will
    be from buildings to the side and rear of his location, with the s/n ratio worsened by the foliage attenuation of the direct signal path.
    1b. His screening device couldn't possibly discriminate between a signal originating from between those buildings and a reflection coming from one
    or both of the buildings. The angle is too narrow.
    2. The screening box-thing is so close to the aerial that it encroaches severely on the aerial's capture area. It's about ?/2 but it needs to at least 2?. It would de-tune the aerial and lower the gain severely. The
    same applies to the dustbin idea.

    My guess is he's done this in ignorance and found it didn't work so he's
    just made out it has.

    Bill

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Brian Gaff (Sofa)@21:1/5 to williamwright on Fri Jan 7 09:22:06 2022
    What he is doing is probably stopping some of the side lobe signals, but in doing so also he is changing the characteristics of the aerial, at the very least its impedance.

    I hat to think what his neighbours might say about having what amounts to an old dustbin on a pole at his property. Obviously I cannot see the pictures,
    but the mind can build pictures!

    I remember in the RF anechoic chamber at Racal, something similar was being done to this but they wre using much higher frequencies which tend to behave differently, you also got some odd side lobes from the edges of the can part which needed to be treated with some kind of carbon coating to stop that.
    Brian

    --

    This newsgroup posting comes to you directly from...
    The Sofa of Brian Gaff...
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    Blind user, so no pictures please
    Note this Signature is meaningless.!
    "williamwright" <wrightsaerials@f2s.com> wrote in message news:j3m56jFdq5pU1@mid.individual.net...
    https://www.instructables.com/HDTV-Multipath-Shield/

    I don't believe this is genuine, for a a number of reasons.

    Bill

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Brian Gaff (Sofa)@21:1/5 to wrightsaerials@aol.com on Fri Jan 7 09:33:40 2022
    Actually, if you are only getting ghosting on one analogue channel some very painstaking fiddling you can often get acceptable results with two aerials offset and adjusting the phasing cable between them, but its not easy. I did
    it as a test here on a severely ghoste relay and it was extremely
    sensitive and the attenuation meant you lost S/N as well.
    Also if your ghosting is from a tower crane, forget it as every time it
    moves it will be different!

    I'd like a sure fire way to remove multipath from FM stations myself. That
    is almost impossible if you live in Leeds and want to listen to the fm local station, and often Humberside is stronger. I used to have relatives there.
    Brian

    --

    This newsgroup posting comes to you directly from...
    The Sofa of Brian Gaff...
    briang1@blueyonder.co.uk
    Blind user, so no pictures please
    Note this Signature is meaningless.!
    "R. Mark Clayton" <notyalckram@gmail.com> wrote in message news:ec8a04fd-0fb0-4b30-9e9f-c6e8811a4be6n@googlegroups.com...
    On Thursday, 6 January 2022 at 02:01:05 UTC, wrightsaerials@aol.com wrote:
    On 05/01/2022 20:03, Mark Carver wrote:
    On 05/01/2022 19:03, R. Mark Clayton wrote:
    On Wednesday, 5 January 2022 at 18:09:26 UTC, wrights...@aol.com
    wrote:
    https://www.instructables.com/HDTV-Multipath-Shield/

    I don't believe this is genuine, for a a number of reasons.

    Bill
    Multipath was certainly an issue for analog TV, and a paler shadow
    image would appear displaced horizontally in the picture.

    Not an issue AFAIK with terrestrial digital TV.
    It's certainly not an issue for DVB-T, but ATSC is a different kettle
    of fish.

    For starters, as the web page shows, it has a 'spot' pilot carrier, I
    need to read up on what purpose that serves ?

    Well anyway, here's why I think it's a made-up article.
    1. He says that the reflections are caused by "signal bouncing back and
    forth between the two buildings" that are either side of the signal
    path. Gibberish.
    1a. If he is suffering multipath it won't be from those buildings; it
    will be from buildings to the side and rear of his location, with the
    s/n ratio worsened by the foliage attenuation of the direct signal path.
    1b. His screening device couldn't possibly discriminate between a signal originating from between those buildings and a reflection coming from
    one or both of the buildings. The angle is too narrow.
    2. The screening box-thing is so close to the aerial that it encroaches severely on the aerial's capture area. It's about ?/2 but it needs to at least 2?. It would de-tune the aerial and lower the gain severely. The
    same applies to the dustbin idea.

    My guess is he's done this in ignorance and found it didn't work so he's
    just made out it has.

    Bill
    +1

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)