BelAir100SN User Guide
Cable Modem Configuration
May 31, 2010
Confidential
Document Number BDTM11001-A01 Released
Displaying the
Cable Modem
Status
/card/cm-<n>/show status
This command displays the operational parameters of the cable modem. For
proper operation, the status must be as follows:
• the
QAM lock
,
FEC sync
, and
MPEG sync
fields must be
yes
.
• the
weak signal
field must be
no
.
• the
downstream power
and the
upstream power
must be in the range
specified in the DOCSIS 3.0 specification.
• the signal-to-noise ratio (SNR) must be 23.5 or higher when the QAM
mode is 64 and must be 30.0 or higher when the QAM mode is 256.
To adjust the downstream and upstream power values, see
.
Example
/card/cm-9# show status
Modem status : Operational
Channel 1 2 3 4
Downstream freq (MHz) : 699 645 657 663
Timing offset (PPM) : 0 0 0 0
Carrier offset (Hz) : -16548 -13034 -15819 -14321
QAM mode : 256 256 256 256
QAM lock : yes yes yes yes
FEC Sync : yes yes yes yes
MPEG Sync : yes yes yes yes
Weak signal : no no no no
Upstream power (dBmV) : 57.0 -1.0 -1.0 -1.0
Downstream power (dBmV) : -17.7 -19.0 -19.1 -19.2
Downstream SNR (dB) : 29.1 28.4 28.5 28.7
Configuring
Attenuation
/card/cm-<n>/set attenuation {upstream|downstream}
{ mode {auto|manual [<att_val>]}
| parameters target <target_val> delta <delta_val> }
This command lets you set the upstream or downstream attenuation applied to
the cable modem’s RF signal path. You can use manual or automatic attenuation
settings. For manual settings, specify the
<att_val>
parameter, which ranges
from 0 to 20 in 1 dB steps. The default value setting is 0 dB.
Set the
auto
parameter to use automatic attenuation. With automatic
attenuation, the cable modem monitors the upstream or downstream power
level and automatically adjusts attenuation to attempt to bring the signal level to
in-lock
range. Refer to the DOCSIS 3.0 specification for specific definitions of
in-lock
ranges for upstream and downstream signals.
