Cisco Cisco Digital Service Access Node (DSAN) 8211 Troubleshooting Guide
Functional Description
4032301 Rev A
11
The DSAN has two output ports:
The Mixed Services output contains the regenerated analog tier (54 to 552 MHz)
combined with the portion of the input above 564 MHz. Due to filter limitations,
there is a guard band of 12 MHz, from 552 to 564 MHz, where the digital signals
are not attenuated sufficiently. As a result, no digital signals are supported in
this band.
combined with the portion of the input above 564 MHz. Due to filter limitations,
there is a guard band of 12 MHz, from 552 to 564 MHz, where the digital signals
are not attenuated sufficiently. As a result, no digital signals are supported in
this band.
The second output, referred to as the Bypass output, is simply an attenuated
copy of the input.
copy of the input.
Tuner Band Mapping
The DSAN is configured from the headend using custom software that applies the
following algorithm to configure the wideband tuners and track QAM usage.
1 Map First Wideband Tuner
following algorithm to configure the wideband tuners and track QAM usage.
1 Map First Wideband Tuner
Map low end of first wideband frequency to lowest frequency of selected
program input channel or QAM.
program input channel or QAM.
Limit tuner to 88 MHz to 1002 MHz frequency range (112 to 978 MHz center
frequencies).
frequencies).
Keep count of the number of QAMs used (we can only use 16 of the 24
QAMs that the 3 wideband tuners support).
QAMs that the 3 wideband tuners support).
2 Map Second Wideband Tuner
Map low end of second wideband frequency to lowest frequency of selected
program input channel after first wideband frequency range.
program input channel after first wideband frequency range.
Limit tuner to 88 MHz to 1002 MHz frequency range (112 to 978 MHz center
frequencies).
frequencies).
Update the QAM count.
3 Map Third Wideband Tuner
Map low end of third wideband frequency to lowest frequency of selected
program after second wideband frequency range.
program after second wideband frequency range.
Limit tuner to 88 MHz to 1002 MHz frequency range (112 to 978 MHz center
frequencies).
frequencies).
If the remaining selected QAMs are not within a 48 MHz band, the channel
map is not valid.
map is not valid.
Rules for Channel Mapping
A channel map is validated based on the following rules:
Output channel numbers are unique.
Valid EIA output channels are 2 through 78 and 95 through 99 (for channel plan