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Billy-Bob
28-12-2009, 12:24
I've noticed that one of the 3 downstream channel power levels for my 50Mb service is higher than the other 2;

Cable Modem Downstream

DS-1 DS-2 DS-3 DS-4
Frequency 306750000 298750000 314750000 N/A
Lock Status
(QAM Lock/FEC Sync/MPEG Lock) Y/Y/Y Y/Y/Y Y/Y/Y N/N/N
Channel Id 61 60 62 N/A
Modulation 256QAM 256QAM 256QAM N/A
Symbol Rate
(Msym/sec) 6.952 6.952 6.952 N/A
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 N/A
Power Level
(dBmV) 6.83 7.23 6.51 N/A
RxMER
(dB) 38.61 38.26 38.26 N/A
Correctable
Codewords 275873 18969 250214 N/A
Uncorrectable
Codewords 3500 294 2139 N/A

I believe this is outside the ideal range (up to 7.00?) for 50Mb, and I'm wondering if it could be contributing to the sporadic drops in speed I've started seeing in the last week (of course, the speed drop is just as likely to be due to the fact that everyone is off work and bored = surfing the internet!)

Is this normal, or should the channel power levels all be about the same?

Ignitionnet
28-12-2009, 14:22
Perfectly normal, some variation is quite acceptable. In your case even more explainable as that's the lowest frequenct. A power difference of less than 0.7dBmV across 3 downstreams is fine.

I wouldn't be too worried about the power levels being high, mine are higher and I'm fine.

DS-1 DS-2 DS-3 DS-4
Frequency 299000000 307000000 315000000 323000000
Modulation 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952 6.952 6.952 6.952
Power Level (dBmV) 9.27 9.53 9.55 9.92
RxMER (dB) 38.26 38.61 39.40 39.40

Billy-Bob
28-12-2009, 15:41
Thanks Broadbandings. :)

Just out of interest, do you know why some people have 4 downstream channels and others have only 3?

Peter_
28-12-2009, 16:16
Thanks Broadbandings. :)

Just out of interest, do you know why some people have 4 downstream channels and others have only 3?
All Motorola BSR's have 4 downstreams and all Cisco 10000's have 3 downstreams, rhe kit that you are on is dependent on the area.

Billy-Bob
28-12-2009, 19:33
All Motorola BSR's have 4 downstreams and all Cisco 10000's have 3 downstreams, rhe kit that you are on is dependent on the area.

Ta! :tu: