[opendtv] Re: 20050627 Mark's Monday Memo

I don't think the CRC is an impartial organization. They have NO 
credibility with me. I would not ask them the time of day.

In fact the only credible test if you are going to make an investment is 
to test yourself and the test we have done so far says that COFDM works 
and has since we first tested it and 8-VSB has not and still does not 
accept maybe with the latest receivers if we are willing to restrict our 
venture to fixed receivers that will cost more than necessary and come 
from a restricted list of manufacturers who themselves are less than 
enthusiastic about the modulation and our prospects as customers using it.

Not real exciting.

You can continue twisting this anyway you want but the reality is that 
in the US few entities of any kind have shown ANY interest in investing 
in 8-VSB at any level unless force, cajoled or MANDATED and that ONE of 
those few, ourselves, is possibly the BIGGEST critic of the modulation 
8-VSB.

The CEA which is maybe one of the biggest proponents of 8-VSB is also on 
record as saying that OTA broadcasting is and should die.

Bob Miller.

Manfredi, Albert E wrote:

>Bob Miller wrote:
>
>  
>
>>If we had an 8-VSB receiver as good as a 1999 COFDM
>>receiver I would not be in doubt about a venture
>>with the  5th gen receivers we have tested so far
>>and would not be up late tonight talking to the Far
>>East about the latest.
>>    
>>
>
>Context is everything.
>
>First of all, in urban canyon reception, COFDM is doing
>exactly what it was designed to do. That's where it's
>*supposed* to shine. So if it does, it should not come
>as a great surprise.
>
>But even in spite of that, real tests by the CRC, an
>impartial organization, provided this result in their
>September 2003 article in the IEEE Transactions on
>Broadcasting:
>
>"As shown in Fig. 4, the DVB-T receiver could handle
>pre and post ghosts over a wider range. It had a window
>of 74 us working within a delay range of -74 to +74 us,
>and capable of resolving zero dB ghost for a signal
>having a high C/N of 31 dB, and less than 1 dB ghost
>for a signal with a C/N of 22 dB."
>
>By comparison, the CRC test on both the LG and the
>previous Linx receivers showed that two 0 dB echoes,
>i.e. three equal strength symbols arriving 1 usec
>apart, as in Brazil E, could successfully be decoded
>with a C/N of only 25 dB. And less stressful profiles
>required C/N margins in ranges well below 20 dB.
>
>So this shows a mixed bag. The 8-VSB receivers still
>cannot match the echo tolerance range of COFDM with
>GI set to 1/16 (50 uS for LG, 74 uS for COFDM), but
>they can beat your 1999 COFDM performance for the
>very difficult Brazil E profile handily, with 6 dB of
>extra margin.
>
>This is what I'm getting at. Depending on specific
>surroundings, your sweeping assessment might apply or
>not. In GENERAL, these tests show what most people
>already know: COFDM is great in areas of high
>multipath. It is very robust. But it is best used
>where signal strength is not a big issue. That's why
>it's good for applications like WiFi. If signal
>strength is an issue, then even in *some* high
>multipath environments, the new 8-VSB receivers might
>have an edge. Unless you do the careful tests,
>sweeping generalizations are not credible.
>
>Bert
>

 
 
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:

- Using the UNSUBSCRIBE command in your user configuration settings at 
FreeLists.org 

- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word 
unsubscribe in the subject line.

Other related posts: