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 ---------------------------------------------------------------------- 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.