Our company recently lost it's old docsis engineer and they kind of tapped me to "help out". I recently converted our old 16qam carrier to 64qam and enabled upstream agility across the board. We are now currently running 3 64 qam 6.4mhz carriers, but I had a question on the modulation profiles that are set up and the spectrum groups that were created for agility reasons.
1) modulation profile
here is a sample mod profile for our 64qam carriers. Are there any tweaks that could be done to help the performance and/or reliability of the network?
Interval Chan Mod Pre Dif FEC FEC Scr Max Guar L Scr ---Atdma--- Prea
Usage Type Type Len Enc T k amb Bur Time C amb Int Int mble
Code En Len Len Seed Siz Size S En Depth Block Type
---------------------------------------------------------------------------------
1 request atdma qpsk 56 F 0 16 338 0 8 F T 1 2048 qpsk1
3 initial atdma qpsk 640 F 5 34 338 0 48 F T 0 2048 qpsk1
4 station atdma qpsk 384 F 5 34 338 0 48 F T 0 2048 qpsk1
9 a-short atdma qam-64 104 F 12 81 338 11 8 T T 0 2048 qpsk1
10 a-long atdma qam-64 104 F 16 223 338 0 8 T T 0 2048 qpsk1
11 a-ugs atdma qam-64 104 F 12 81 338 0 8 T T 0 2048 qpsk1
I have seen some notes online about changing the station maintenance to 16qam.
2) spectrum group
IUA Trap: Disabled
Group 36:
Min Codewords 1000
Sample Period 10
Hop Period 10
Retry Period 10
Channel Modulation
Group State Freq(Hz) Width Prof
36 1 36350000 6400000 64
36 2 36350000 6400000 32
36 3 36350000 3200000 64
36 4 36350000 3200000 32
36 5 36350000 3200000 17
Group State Next Trigger
36 1 2 10 degradation {ufec_err > 3000 OR fec_err > 4000} AND {snr < 270}
36 2 3 10 degradation {ufec_err > 3000 OR fec_err > 4000} AND {snr < 270}
36 2 1 20 improvement {ufec_err < 1000 AND fec_err < 2000} AND {snr > 300}
36 3 4 10 degradation {ufec_err > 3000 OR fec_err > 4000} AND {snr < 270}
36 3 2 20 improvement {ufec_err < 1000 AND fec_err < 2000} AND {snr > 300}
36 4 5 10 degradation {ufec_err > 3000 OR fec_err > 4000} AND {snr < 270}
36 4 3 20 improvement {ufec_err < 1000 AND fec_err < 2000} AND {snr > 300}
36 5 4 20 improvement {ufec_err < 1000 AND fec_err < 2000} AND {snr > 300}
Should I try tightening up the triggers on the above for the fec/ufec and snr? currently most of our upstreams are running around 32-34db after I have had the guys go out and do some tweaking in the field/ingress correction.
I have been trying to learn this in a short amount of time, so any help that you could provide or a direction of learning materials would be greatly appreciated.
Thank you,
Craig D.