Quote:
Originally Posted by

**dr1394**
As it turns out, the ATSC 3.0 folks have already considered using LDPC and BCH error correction codes with 8-VSB.

http://atsc.org/cms/pdf/pt2/02-PT-2-...-Yiyan-V10.pdf
On page 40, it looks like a 24 Mbps service is possible at 15 dB S/N ratio.

Ron

I'm doing my best to understand this. In another link you posted there was a table that said that the ATSC symbol rate is 10.76 Msymbols/S or 32.28 Mbps. Looking at the graph on page 40, that would correspond to a Shannon limit of about 20 dB C/N. This is what I read somewhere else as the essentially error-free C/N requirement with no error correcting.

If I understand this correctly, the Data Rate label is actually the Data Payload Rate, a term used in your other link. Data Payload Rate meaning the actual useable data which is what's left over after all overhead is accounted for; i.e., error correction and whatever else there is.

So it appears that the newer error correction schemes use fewer bits to achieve the same level of error correction as the current ATSC system does thus resulting in a greater Data Payload Rate.

Further it appears that all this error correction has been implemented to reduce the useable C/N from around 20 dB to 15 dB.

On top of greater error correction efficiency with these newer methods, there's also greater data compression efficiency that can be achieved by moving from MPEG2 to MPEG4.

Do I have this correct or have I missed something?

At the end of the presentation it is stated that OTA can never compete with satellite or cable in terms of bandwidth efficiency. I assume this is because the latter two don't need any error correcting. But it is also stated that OTA has its own advantages.

Chuck