SMC Networks TigerAccess SMC7816M - Manual (Page 254)

VDSL C
ONFIGURATION
10-2
- Power Value – A power level for each of the PSD breakpoints.
(Range: An integer from 0 to 255, which is used to calculate a power
level in terms of -140 + (power-value) * 0.5 dBm/Hz;
Default: 255, which is equivalent to -12.5 dBm/Hz)
Breakpoints, which are defined by a signal frequency and corresponding
power level, create a PSD mask for in-band spectrum shaping, set the
Limit PSD Mask required for compliance with local regulations, or set
mask limits for upstream power backoff. The methods used to calculate
these various PSD masks, and local regulations governing the power
spectrum used on VDSL lines are all described in ITU-T G.993.2.
Breakpoints can be applied to any upstream or downstream channel
depending on the associated frequencies.
Note that settings for the MIB PSD mask can only be configured
through an SNMP network management interface.
• PSD Mask Level – Sets a predefined PSD mask. (Options: See
Table 29-6, “PSD Mask Options,” on page 29-17; Default: 5, Annex F)
• UPBO – Enables upstream power backoff. (Default: Disabled)
Upstream power backoff (UPBO) should be configured when there are
VDSL connections of different lengths attached to this switch. UPBO
is required to improve the spectral compatibility on lines of different
lengths by reducing the transmitted power on shorter lines. If UPBO is
enabled, the transceiver will use the PBO mask as defined in the UPBO
Configuration table. Additional information about the power backoff
PSD mask can be found in ITU-T G.992.2. If UPBO is enabled, but a
PBO mask has not been configured, the specified transceiver will
automatically control upstream power backoff based on default values
set by the DSP engine
• Rate Adaption – Enables automatic line rate adaptation, which can set
the optimal transmission rate based on existing line conditions.
(Default: Enabled)
The data rate on a VDSL line can be affected by factors such as
temperature, humidity, and electro-magnetic radiation. When rate
adaptation is enabled and the port links up, the switch will determine