Forum Discussion

Viper-t's avatar
Viper-t
Fibre optic
3 years ago

Qam wrong?

Hi can someone tell me if my qam is wrong please?. My upload qam is always 64 as is everyone's I have 1 channel 32qam and 2 at 16qam I think 64 symbols is more data than 16 no? 

Upstream channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

14310000041.35120 KSym/sec32QAM2
23010000040.85120 KSym/sec16QAM4
336600000415120 KSym/sec16QAM3
44960000041.55120 KSym/sec64QAM1
523600000405120 KSym/sec64QAM5
  • Channel Channel Width (MHz) Power (dBmV) FFT Type Modulation

    610.838.82KQAM8

     

    The channel width doesn't seem right to me.  As in not being centred in the upstream spectrum.  10MHz would be centred.

    Indeed, if you look in the forum for threads about DOCSIS 3.1 upstream issues, nearly all of them are not centred on 10MHz.

    I can't be sure that 10.8 and 10.4 (which I also see in the problem threads) are not within tolerance as I'm still learning D3.1, but the Cablelabs spec does not mention any off-centre tolerance that I could find.

    I wonder what the Forum Team will make of what I've suggested and if I'm wrong, I apologise for work others may have to do!