[opendtv] Re: Digital radios outstrip analogue

At 3:23 PM -0500 3/2/05, Manfredi, Albert E wrote:
>Craig Birkmaier wrote:
>
>>  What I was trying to ask is why do we have multiple
>>  infrastructures for broadcasting different services.
>
>One size doesn't fit all. For radio, more robust, less
>spectral efficiency affordable. For TV more spectral
>efficiency required, less robustness more easily
>tolerated. (This is high quality TV, not the cell phone
>kind.)

Yes Bert, we have already been over this. You can satisfy all of 
these requirements with a single properly designed digital broadcast 
infrastructure.

Not only this, but it is NOT correct to lump all video services 
together. There is a continuum from high quality video services that 
require high bit rates, with less robustness to lower bit rates with 
more robustness. Even the ATSC understands this, although 2VSB is 
never likely to be used by broadcasters.


>The analog world accommodated this as easily as the
>digital world can. There is a small sliver of spectrum
>just above TV Channel 6 (in the US) for radio. So in
>fact, it does use the same infreastructure, depending
>how you define infrastructure.

The analog world did NOT accommodate this. It required completely 
different transmission infrastructures for TV and radio and different 
receivers. The existence of appliances that integrate both is NOT a 
valid proof of concept; it is just the integration of multiple 
receivers in an appliance that happens to share the same speaker and 
volume controls.

I define infrastructure as the transmission system that exists to 
support a service. As I pointed out yesterday, we have MORE antenna 
infrastructure in the U.S. to support separate radio and TV services 
than we would need to implement a properly designed digital broadcast 
system.

The only sharing of infrastructure between Radio and TV is when we 
put both TV and Radio antennas on a common tower.


>Digital radio often operates at less than 1 b/s/Hz. Do
>you really think it makes sense to run TV over that?

Why would I want to? I would use an appropriate service constellation 
for each application. A properly designed digital broadcast 
infrastructure can support multiple levels of service simultaneously, 
and the mix of services can be adjusted dynamically based on demand.

Regards
Craig
 
 
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