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Posted by Roy L. Fuchs on 01/02/06 05:40
On Mon, 02 Jan 2006 04:27:25 GMT, Bob Miller <robmx@earthlink.net>
Gave us:
>Roy L. Fuchs wrote:
>> On 31 Dec 2005 21:18:41 -0800, "G-squared" <stratus46@yahoo.com> Gave
>> us:
>>
>>
>>>BTW ghosts (multipath) are a BIGGER problem in digital than analog.
>>
>>
>> NOT! Look up diversity receiver! Here's a sample of why NOT!
>>
>> Try http://www.avalonrf.com/ for just ONE player in the digital
>> realm game. They are the MASTERS at signal discrimination.
>>
>> Just ask anyone at a race track or anyone in Hollywood, or anyone on
>> the flight deck of an aircraft carrier. They ALL use diversity
>> receivers.
>>
>> Do a search on diversity receiver(s).
>>
>> Either the packet makes it in, or it doesn't. The standard
>> currently rests somewhere around 10% bit error rate.
>>
>> There's another one for you. Research "bit error rate".
>
>>
>Roy is right. In digital ghosts or multipath are a piece of cake. The
>problem in the digital world of the US is 8-VSB that was never designed
>to handle multipath (ghost). Others did design for it and the problem
>does NOT exist, is NOT a problem in this real world.
>
>Multipath is ONLY a problem in the retrograde political techno gunk that
>is the US digital TV transition.
>
>As your posted URL says diversity is key.
>
>And using diversity receivers (COFDM) and a diversity network
>COFDM/SFN) with "true diversity" antennas with smart receivers would be
>the best way to design a modern broadcast network.
>
>COFDM is diversity of Frequency (Coded Orthogonal Frequency Division
>Multiplexing).
>
>Using COFDM in an SFN (Single Frequency Network)is transmitter diversity.
>
>Using COFDM with "true diversity antennas" and smarts allow for the last
>leg in the best of all reception environments.
>
>http://www.dibcom.net/us/document/Aviero.pdf
>http://makeashorterlink.com/?B3065166C
>
>A dibcom diversity receiver is being used in this video. It is attached
>to the screen attached to the seat back. This receiver not only will
>allow the use of up to six antennas but will add the signals from each
>to one strong signal. In this video we are using two antennas attached
>to the dibcom receiver. The other two videos are using single antenna
>receivers.
>
>This is also a one transmitter test. There is no SFN which would have
>been even better. And the 100 Watt transmitter is at only around 400 feet.
>
>www.viacel.com/bob.wmv
>
>In New York City the Dibcom diversity receiver worked best when at
>higher speeds when Doppler is the main culprit of decent reception.
>
>So Roy has it absolutely right.
>
>Multipath is NOT even a slight factor in reception with todays modern
>technology. It is only a factor when using outdated technology that was
>ill designed and obviously outdated.
>
>No one in their right mind would use 8-VSB or ENG for example. ENG is
>now being used in helicopters in the US to gather HD news in real time.
>If multipath were a PROBLEM then this scenario surely would not work
>since the helicopter is normally MOVING pretty fast and all signals it
>sends would suffer from intense dynamic multipath.
>
>They use COFDM for ENG.
>
>Bob Miller
Thanks. My biggest problem is that I am an asshole with little
patience. So every time I tick somebody off, they scowl and kill off
a few hundred thousand more brain cells! Making the problem even
worse. :-]
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