System information

BSR 64000 Configuration and Management Guide
6-22
Setting the Upstream Power Level
The cable interface controls CM output power levels to meet the desired upstream
port input power level. Input power level adjustments to an upstream port compensate
for cable interface signal degradation between the optical receiver and the upstream
RF port. You can configure the upstream input power level in either absolute or
relative mode.
• If the upstream input power level is set to the absolute mode, the input power
level does not change when the upstream channel width is changed. Defining the
input power level in absolute mode could possibly cause upstream return lasers to
clip on a completely populated upstream channel.
• If the upstream input power level is set in relative mode, the input power level
changes when the upstream channel width is changed. For example, if the input
power level is +11 dBmV for a DOCSIS 3.2 MHz upstream channel bandwidth
setting in relative mode and is changed to 1.6 MHz, the default receive power is
+8 dBmV. The default power levels for the 3.2 MHz and 1.6 MHz channels are
equal relative to their respective channel bandwidth settings.
Table 6-4 describes how the upstream channel bandwidth corresponds to the input
power-level range and default power-level range for a specific upstream channel.
Caution: If the power level is not explicitly set on the upstream interfaces,
they default to 0 dBmV in absolute mode with a 3.2 MHz, 2560 kilosymbols
per second rate. Ensure that the correct power level is set on each upstream
channel.
Table 6-4 Upstream Input Power Level Range Parameters
Upstream Channel
Bandwidth
Default Power-level
Range
Power-level
Range
200 KHz -1 dBmV -16 to +14 dBmV
400 KHz +2 dBmV -13 to +17 dBmV
800 KHz +5 dBmV -10 to +20 dBmV
1.6 MHz +8 dBmV -7 to +23 dBmV
3.2 MHz +11 dBmV -4 to +26 dBmV