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Okay maybe its just me being paranoid, but I swear it seemed more than just coincidence.

Over the weekend while watching some OTA Hdtv, for the most part I was getting fairly decent picture quality. (Signal strength in the 70's). But rarely on occasion, (like once an hour or so), the signal would start breaking up. Now during the quiet moment (since no signal, also usually means no sound), my hearing would immedtialy pick up a plane flying overhead. (closest airport is 15 miles) And as soon as I stopped hearing the plane, the picture usually would be back to normal, or near resyncing.

Now like I said, I might just be paranoid or something but it happened at least like 4 times over a 3 day period. But could an airplane reflection really cause this?


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Tho!
 

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If you can switch over to the NTSC channel coming from the same tower at that time, you'll probably get a "fwup-fwup-fwup" sound, along with picture shifts, caused by the signal bouncing off the aircraft. We get that here depending on the wind direction, causing the airport to re-direct traffic.


Depending on trees and other obstacles between you and the TV tower, the reflected signal may overpower your regular signal.


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--Roland W. Fox
 

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Quote:
Originally posted by junkman:
Okay maybe its just me being paranoid, but I swear it seemed more than just coincidence.

Over the weekend while watching some OTA Hdtv, for the most part I was getting fairly decent picture quality. (Signal strength in the 70's). But rarely on occasion, (like once an hour or so), the signal would start breaking up. Now during the quiet moment (since no signal, also usually means no sound), my hearing would immedtialy pick up a plane flying overhead. (closest airport is 15 miles) And as soon as I stopped hearing the plane, the picture usually would be back to normal, or near resyncing.

Now like I said, I might just be paranoid or something but it happened at least like 4 times over a 3 day period. But could an airplane reflection really cause this?

Welcome to the world of dynamic multipath. Birds, traffic and wind driven leaves can do the same thing. This is why 8-VSB doesn't work mobile. When the receiver is moving everything in the landscape is moving relatively and therefore the source of dynamic multipath.


The US FCC unselfishly sacrificed the ability to handle dynamic multipath in the interest of denying broadcasters the ability to do mobile datacasting or at least that is the way it was interpreted by many.


Now we will have the best of both worlds, dynamic multipath interference and multicasting.


In Australia, ironically, they legislated datacasting dead and dealt with dynamic multipath scientifically. They adopted a system that can handle dynamic multipath.


Now which is better to have a brain dead TV broadcast system and datacasting or to have a modern TV broadcast system that works and no datacasting?


Australia seems to think neither. They are about to change the law and allow datacasting. So they will have a viable broadcast system that isn't interfered with by every passing plane and datacasting while we will have a system that cannot handle dynamic multipath but we will have datacasting. Go figure.


Do you think maybe we just got taken in by BS?

 

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Having dealt with the after effects of several FCC regulations that seem (to me) ignorant of anyone who doesn't live in a little cottage in Iowa with a white picket fence, I am really beginning to wonder if the people making the rules have ever lived in an east coast urban environment or been renters.


8VSB works great, but only if there's no source of multipath. Let's rule out urban dwellers and anyone who can't install a large directional antenna on the roof.


OTARD is a giant step in the right direction but has a lot of holes in it that prevent most urban apartment residents from ever being able to take advantage of it.


And let's not forget waivers. Back to that large rooftop antenna again that is necessary to receive the Grade B signal from the station 75 miles away claiming ownership over your viewership.


When I got my Echostar 6000 receiver, I couldn't wait to watch some DTV. I was foolish enough to think that digital would be immune to the the analog receptions nightmares that kept me tethered to the cable company.


Now, 4 antennas and a lot of frustration later, I've pretty much given up on it. It's not a lack of signal. It's the darn multipath and the fact that there is no rooftop antenna ever going to happen here.


I'd love to invite some FCC commisioners over to my apartment for an afternoon and challenge them to set up adequate reception facilities here within their own regulations.
 

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Quote:
Originally posted by Mongo
Having dealt with the after effects of several FCC regulations that seem (to me) ignorant of anyone who doesn't live in a little cottage in Iowa with a white picket fence, I am really beginning to wonder if the people making the rules have ever lived in an east coast urban environment or been renters.

The proper word is arogant not ignorant. How can you possibly suggest that the FCC is ignorant of your plight. Whether you have reception at all is not even on their list of concerns. If you want to know what they are concerned about look at the invite list at the pow-wow Congressman Tauzin, head of the House Commerce Committee, held last Thursday and proposes to hold every few weeks.


URL= http://www.tvinsite.com/broadcastingcable/index.asp?layout=story&doc_id=50764&display=breakingNews]http://www.tvinsite.com/broadcastingcable/index.asp?layout=story&doc_id=50764&display=breakingNews[/url ]


This is not a list of those who want to solve your problem. This is not a list of those who seriously want to address the stalled DTV transition. This is a list of special interest wedded to the current fiasco and dedicated to "staying the course". They think they own the spectrum not you.


All the usual suspects, no engineers, no one that would possibly have a new thought. And no one who represents you. You are supposed to be happy with cable if you live in the city. Never mind that it is your spectrum to and there is a perfectly good way to ensure you can easily and inexspensivly receive OTA DTV today.
 

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Comment posted from DGTEC user in Australia concerning problems and airplane interference...


Message 1 in thread

From: Shaw Goh \\(At Home\\) ([email protected])

Subject: Just got my DGtec

Newsgroups: aus.tv.digital

View this article only

Date: 2001-10-13 03:05:20 PST



I couldn't help myself...went into Sony Central in Perth, looked at it, they

had stock, so I had to have it!


My take so far:-

- Lipsync problem is HUGE. At times the picture lags behind by more than

a second. Not good. But I know that as an early adopter, problems are

expected. So far, this has only occured with Channel 10 - both HD (demo) &

SD. As others have noted, changing channel may provide temporary relief.


- ABC (all except ABC Kids) not transmitting AC3 is driving me nuts. My

Sony STRDB930 receiver does not like it and will squeal VERY loudly. I know

that changing to MPEG sound works, but I like to keep it in AC3.


- Reception performance has so far been perfect. Where I live, small

planes fly over all the time. This causes much inteference on analogue.

None on Digital. Even the microwave no longers cause a problem.


- I love the freeze button!
 

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I live near the intersection of Middlefield and Shoreline (Near 101 in Mountain View). Moffett Field is right across 101, maybe a mile from my location. They fly a lot of big transport planes into there, and when they do, I often get picture breakups.


It's definitely the planes.. It effects the very strong signals, and is often the only breakup that I experience.
 

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I not only live in the flight path but I am a block away from a hospital. We have helicopters flying in and out 24 hours a day.


The trees, which cause their own set of reception problems, do a pretty good job of attenuating the sound but everything flying around here makes a real mess out of the DTV reception and sometimes the satellite signal.
 

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Quote:
Originally posted by Mongo
I not only live in the flight path but I am a block away from a hospital. We have helicopters flying in and out 24 hours a day.


The trees, which cause their own set of reception problems, do a pretty good job of attenuating the sound but everything flying around here makes a real mess out of the DTV reception and sometimes the satellite signal.
Take a note from Australia, no airplane problem there. Dynamic multipath is fixed already there. The scientist that designed that system were trying to improve TV reception not just match a failing NTSC system like Zenith did in the US. So in the US don't expect the big 8-VSB "FIX" to have ANY that is ANY effect on this problem. Remember in 1999 NxtWave announced that they had fixed 8-VSB and that it would work in a mobile enviroment. It didn't, they hadn't, they haven't and they won't.


This was known all along and dynamic multipath can cause interference to anyones reception with the right interferer. That could be anything that moves. birds, planes, traffic, leaves, waves, sailboat mast etc. The fact that 8-VSB doesn't work mobile tells it all. When you are mobile even primary LOS signals take on the characteristics of dynamic multipath.


There is a system that works, the rest of the world has chosen it including Australia. Their receivers are already much less expensive than 8-VSB receivers and will get even less expensive. 8-VSB receivers on the other hand will stay high in price as they try to build more brute force into their silicon to solve problems like dynamic multipath already solved by most of the more advanced world around us.


That was why it was so important to pick a modern broadcast system that works.
 
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