[mythtv-users] Re: New MythTV Hardware Review

Rudy Zijlstra mythtv at edsons.demon.nl
Fri Dec 10 10:53:46 UTC 2004


nate s wrote:

>Nah, here in the US we are far too arrogant to adopt other countries
>standards :)
>
>I thought that QAM was only good over cable.  I didn't know it could
>work OTA as well.
>
>-Nate
>
>
>  
>
And satellite uses QPSK (also called QAM-4).

Still do not understand why US had too choose 8VSB for ATSC. Check the 
testing the australians did when choosing there system. In the end ATSC 
because of the infamous HD table (thus forcing a number of HD 
capabilities), and DVB-T (QAM based, better reception and echo 
cancellation) for transmission.

>On Fri, 10 Dec 2004 00:08:58 +1100, Hamish Moffatt <hamish at cloud.net.au> wrote:
>  
>
>>On Sun, Dec 05, 2004 at 11:54:42PM -0800, Brad Templeton wrote:
>>    
>>
>>>ATSC is in fact the only reason people are putting up new antennas.  If
>>>you get satellite, you must use an antenna to get your local stations.
>>>The satellite companies don't have the bandwidth to feed all the locals
>>>in HD, not yet.   For your HD-cable, you can get it without an antenna.
>>>
>>>The protocol for that is called QAM, it is different from ATSC and DVB.
>>>Whether they would let you put a cablecard into a PC and an open
>>>source PVR is an interesting question.
>>>      
>>>
>>FWIW, DVB-T uses QAM (16, 32, 64, 128).
>>
>>    
>>
>>>Anyway, the pcHDTV card we are all talking about is rumoured to have
>>>QAM support in development, so it could tune your cable and you
>>>would not need an antenna.  As to when, who knows?
>>>
>>>The QAM signal for your local stations should be unencrypted.  The
>>>      
>>>
>>This is a bit confusing; the encryption would be at the MPEG level,
>>with QAM just being the analog modulation used to carry the MPEG
>>data stream.
>>
>>Any chance the USA would like to adopt DVB-T? :-)
>>I hear that QAM is better than 8VSB also (your OTA modulation).
>>
>>Hamish
>>--
>>Hamish Moffatt VK3SB <hamish at debian.org> <hamish at cloud.net.au>
>>
>>
>>    
>>



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