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How to set the level of a D3.1 OFDM carrier
DOCSIS 3.1 OFDM Carrier DOCSIS 3.1 OFDM Carrier
DOCSIS 3.1 OFDM carrier power levels should be measured and referenced in comparison to the
power in a 6MHz carrier.
In a flat system, the average power of the OFDM, referenced to a 6MHz carrier should be set to the
same power level as the adjacent 6MHz QAM 256 carriers.
NOTE: The TOTAL power of the 96 or 192 MHz OFDM carrier is greatly different than the average power in a 6MHz bandwidth.
Total power of 96/192MHz wide carrier: This is not referenced to a 6MHz carrier
Total Power = Total Power PER Channel (6MHz) + 10log
10
(Channel Bandwidth).
Where Channel Bandwidth would be overall OFDM Bandwidth/6MHz channel bandwidth = # of 6MHz Channels :

for a 96MHz wide OFDM carrier the TOTAL power will be 12.04dB higher

for a 192 MHz wide OFDM carrier the TOTAL power will be 15.05dB higher
NOTE: DON’T USE THE TOTAL OFDM POWER to ADJUST CMTS OUTPUT POWER
(This would be like using the total integrated power of 32 DOCSIS QAM carriers to set the level)
Example: Single 6MHz channel power = 5 dBmV

Total Power(96MHz channel) = 5dBmV + 10log
10
(16) = 5 + 12.04 = 17.04dBmV

This is what some spectrum analyzers
(like R&S FSW) show
SC-QAM