This feature presents impulse noise events in the upstream frequency range across the entire DOCSIS 3.1 US spectrum (0-200 MHz). Impulses are short, sub-millisecond bursts of energy. DOCSIS 3.1 Proactive Network Management (PNM) introduces MIB tables that can capture and records events, presenting their occurrence, average energy, and duration. Standard MIBS are supported and both the E6000 CER and CISCO CMTS need to be implemented.
Important: Performing impulse noise
capture is service-impacting. To perform a capture, an SC-QAM channel must be inactive
and removed from service. ServAssure NXT must be capable of determining
whether or not the current upstream channel in the US Spectrum Analyzer is in the
correct state. If the connector group of the channel has no channels in Measurement
mode, an error message is shown when you attempt to start the capture using the
Play
button.
ServAssure NXT supports capture of DOCSIS 3.1 Impulse Noise events on supported devices and is part of the Upstream Spectrum Capture tool. Specifically:
- Capture events consist of three values:
- timestamp of when the event occurred.
- average power in dBmV of the event.
- duration of the event in microseconds.
- Events are captured over a specified duration which cannot exceed 60 seconds (E6000 CER requirement).
- Events can be captured over an automatic duration of 60 seconds. The capture automatically stops when it reaches 60 seconds.
- Event capture can be halted, and events can be viewed, before the capture duration expires. Data is saved and not deleted when the capture is halted.
- Events can be measured at specific portions of the Upstream spectrum and centered around a frequency.
- Events are captured based on set start and end thresholds.
- A user can see the most recent events captured, up to a maximum of 1024 events. Once 1024 events occur, the 1025th event will overwrite the first event, and so forth.
- Event capture uses the FTP protocol to retrieve noise capture information from the device. This file is written at the termination of a capture and is not archived in the system once retrieved. Connectivity between the system and device requires a username, password, and port number.
- Upstream impulse noise capture is supported starting from E6000 CER firmware version 8. Configuration changes are required on the CMTS side using the CLI. SNMP-based configuration is not supported. This is a service-impacting event; the SC-QAM upstream channel being used for capture must be in measurement mode and removed from service.