We are experiencing a situation with our cable plant and setting the levels. What is the best RF signal level hitting at The cable modem? I have done some investigating and the best level I have found is between 11 and 16db. I have found the modem operates and functions properly. Outside this range we start to experience problems. I have talked to the lead technician and he is claiming that we can not support that because the signal would be too high for the tv's too handle. It would start to overload and ruin our customers' tv's. He thinks old school and has been doing this for 30 years, so it is all forward path thinking. I try to explain to him that when the reverse is introduced to the system, it is a whole new ball game. What is the line for level management between Modem and your basic cable system?
Information:
Cable Plant: Running analog with digital high def over qam
CMTS: Running Docsis 2.0
Modem: Motorola SB5102
Input would be greatly appreciated
Docsis spec says receive level is -15 to +15. so with 0 +/- 15, I find they run best with 0 +/- 10. when you get close to that edge of the window is when you start to have problems. the transmit level from the modem back to the headend should be around 45 with a signal to noise of 21 and higher for 16Qam and snr of 28 and higher if you plan to run 64Qam on the return
Hi!
I think your old technician is right :) . 11 - 16dbm is litle to high for downstream , when I worked as a RF tech -10 to 0 was optimal range . As for upstream you are setting it separately and does not efect downstream . Optimal power levels as I remeamber ware about 45 to 50 dBm for modem to transmit.