Archived from groups: alt.tv.tech.hdtv (More info?)
Posted by mitchrc on AVSForum...
That is true, but COFDM can't (or couldn't 3 years ago) carry HDTV in a
6mhz channel because of it's lower payload. ATSC was specifically
designed to fit into 6mhz channels, which was a requirement going into
this whole switchover. The broadcasters were originally asking for 9mhz
allocations and the FCC refused.
Correct answer....
COFDM could do 19.76 Mbps while mobile or portable in 1998. Six years
later, NOW, 8-VSB is still limited to 19.34 Mbps fixed if you are lucky
or if you wait for 5th generation LG receivers.
COFDM DVB-T was demonstrated at the hearings in 2000 by Sinclair doing
1080i HDTV using 19.76 Mbps and was received on a simple bow tie $2
antenna that was walked around the hearing room with no loss of signal.
This was not possible with 8-VSB which required that their Silver Sensor
antenna had to be fixed with tape to a window in a particular position
for reception using 19.34 Mbps.
COFDM was demonstrated by Sinclair in early 2000 at NAB in a
hierarchical mode which allowed for the simultaneous delivery of a
mobile SD program and a 720P HDTV program to be broadcast in ONE six MHz
channel. Reception was so good that even when inside the convention
center reception could not be lost with a simple antenna even when it
was put inside of an active transmitter cabinet while four years later
8-VSB was not reliable enough to be received at NAB even when the
receiver was next to a large floor to ceiling window at the demo site.
Same problem as in the hearing of 2000, the demonstrators did not want
to "risk" an incident of multipath interference.
It is amazing that you can still post such garbage like "COFDM's data
rate 3 years ago was inadequate" when a Google search will tell you the
truth.
Posted by mitchrc on AVSForum...
That is true, but COFDM can't (or couldn't 3 years ago) carry HDTV in a
6mhz channel because of it's lower payload. ATSC was specifically
designed to fit into 6mhz channels, which was a requirement going into
this whole switchover. The broadcasters were originally asking for 9mhz
allocations and the FCC refused.
Correct answer....
COFDM could do 19.76 Mbps while mobile or portable in 1998. Six years
later, NOW, 8-VSB is still limited to 19.34 Mbps fixed if you are lucky
or if you wait for 5th generation LG receivers.
COFDM DVB-T was demonstrated at the hearings in 2000 by Sinclair doing
1080i HDTV using 19.76 Mbps and was received on a simple bow tie $2
antenna that was walked around the hearing room with no loss of signal.
This was not possible with 8-VSB which required that their Silver Sensor
antenna had to be fixed with tape to a window in a particular position
for reception using 19.34 Mbps.
COFDM was demonstrated by Sinclair in early 2000 at NAB in a
hierarchical mode which allowed for the simultaneous delivery of a
mobile SD program and a 720P HDTV program to be broadcast in ONE six MHz
channel. Reception was so good that even when inside the convention
center reception could not be lost with a simple antenna even when it
was put inside of an active transmitter cabinet while four years later
8-VSB was not reliable enough to be received at NAB even when the
receiver was next to a large floor to ceiling window at the demo site.
Same problem as in the hearing of 2000, the demonstrators did not want
to "risk" an incident of multipath interference.
It is amazing that you can still post such garbage like "COFDM's data
rate 3 years ago was inadequate" when a Google search will tell you the
truth.
/staff.washington.edu/mrc
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