Rinciple, Hart, Ypical – Thor 1- 4 HDMI to QAM Modulators User Manual
Page 7: Pplication of, Arrier, Utputs
H-4SDI-or-4HDMI-QAM-IP
1.5 Principle Chart
1.6 Typical Application of 4 * Carrier Outputs
As we all know, to guarantee the picture quality of 1920x1080@50I/60I resolution HD
program, the video bit-rate may exceed 10 Mbps, and even reach up to 15Mbps.
However, when the modulating constellation is 64QAM (with 6MHz bandwidth), the
maximum possible bit-rate output for single DVB-C carrier is only around 20Mbps.
15Mbps x4 =60Mbps > 20Mbps.
It means the single DVB-C carrier simply can't carry the 4 channels 1080i HD
program if the average bit-rate exceeds 10Mbps.
That's why we designed 4*DVB-C carrier modulation board which quadruples the
maximum possible bit-rate bandwidth up to 80Mbps and above when 64QAM
constellation is used. This breakthrough makes it possible to reliably carry 4 channels
of MPEG2 HD programs output simultaneously.
Below this chart will help to clearly illustrate the working principle.