When SNR or CER levels on a channel are bad, the CMTS modulates the channel to a lower QAM, reducing the level of CER. The lower modulation causes the per-channel utilization to increase, because the lower QAM cannot transfer as much data. You can see these modulation changes for selected frequencies.
Modulation switching displays graphic indicators for SC-QAM upstream graphs when modulation goes up or down.
Modulation change options appear on the Display tab.
- Select a single
frequency or multiple frequencies from the drop-down.
Graphic indicators appear in the displayed graph. Green indicates increasing modulation and red indicates decreasing modulation. Three dots indicate multiple frequency readings that are situated on top of one another.
To view a frequency reading- Hover over a
modulation indicator. For this example, multiple
frequencies were selected, and the indicator has multiple
modulation changes at the same time (on Fri the 14th). Two
frequencies (34 MHz and 22.8 MHz) switched modulations.
34Mhz decreased from QAM64 to QM16, and 22.8 MHZ decreased
from QAM64 to QAM16.
- In this
example, a single frequency is selected:
- Hover over a
modulation indicator. For this example, multiple
frequencies were selected, and the indicator has multiple
modulation changes at the same time (on Fri the 14th). Two
frequencies (34 MHz and 22.8 MHz) switched modulations.
34Mhz decreased from QAM64 to QM16, and 22.8 MHZ decreased
from QAM64 to QAM16.