4 ms·
On the technical side, the patent is for Non-Uniform Constellations or NUCs. It's a modification of the modulation constellation points to match the error codin
by drmpeg 3y ago
On the technical side, the patent is for Non-Uniform Constellations or NUCs. It's a modification of the modulation constellation points to match the error coding.
Traditional 64QAM:
https://www.w6rz.net/64qamrect.png https://www.w6rz.net/64qamrect.png
ATSC 3.0 64QAM for 9/15 code rate:
https://www.w6rz.net/64qamnuc.png https://www.w6rz.net/64qamnuc.png
You can explore this with my open source ATSC 3.0 transmitter.
https://github.com/drmpeg/gr-atsc3 https://github.com/drmpeg/gr-atsc3
Demo clip.
https://www.youtube.com/watch?v=cmIGM0I3NE0 https://www.youtube.com/watch?v=cmIGM0I3NE0
- hatsunearu 3y agoI was always surprised why QAM uses a rectangular I/Q coordinate rather than a radial one like how 8PSK does it. It would seem like a radial pattern maintains better ISI margin just from inspection.
- drmpeg 3y agoWith less error coding (13/15 code rate), the constellation is more rectangular. https://www.w6rz.net/64qamnuc1315.png https://www.w6rz.net/64qamnuc1315.png With really heavy error coding (2/15 code rate), the constellation becomes almost unrecognizable with points very close to each other. https://www.w6rz.net/64qamnuc215.png https://www.w6rz.net/64qamnuc215.png
- abnry 3y agoWow. There must be some interesting coupling between the coding and the constellation/modulation.