Ingress, impulse, and AWGN captures work the same as a manual capture, except you cannot change Type, IUC, Service Identifier, or Domain. To perform one of these captures:
- Open the US Spectrum Analyzer application; see Access upstream spectrum analyzer.
- Enter a CMTS name and channel
string in the format like:
<CMTS name>@<channel string>. You can also select an item from Search History as described in Search channel. - Select Compatibility from the Mode drop-down menu.
- Select AWGN, Ingress, or Impulse from the Analysis drop-down.
- If your Domain value is Frequency you can optionally set markers, as described in Set markers.
- Specify a value for Sample Count as described in Domain.
- Specify a value for Capture Interval as described in Domain.
- Optionally, you can specify a custom range for the X and Y axes, as described in Set up X and Y axes.
- Press Play to start the capture.
- Extend analysis time if needed. See Extending analysis time.
Once a capture has started, there are
“haystacks” showing the DOCSIS Power Envelope at the other upstream channels on this
channel’s port. In this image, they are the curves in black (this channel) and grey
(the other channels on this connector).
NOTE: Power envelopes for
non-selected channels may be missing for some CMTS types or versions.
The channel envelope for an OFDMA
channel on E6000 CER CMTS is computed using the configured power (targetRxPower) of
the OFDMA channel instead of zero. The total channel power across the channel's
bandwidth is calculated by adjusting the configured power (from its default
measurement bandwidth) to the channel's actual bandwidth. The channel envelope power
is then normalized to the width of the channel that is currently selected (active
channel).
NOTE: This computation and
normalization applies only to OFDMA channels on E6000 CER CMTS; computation for
SCQAM channels remains unchanged and uses the configured RxPower of an active
channel.