Broadband Audit – On Site System Audit

On a Site System Broadband Audit The Volpe Firm Inc. will evaluate and test the RF alignment of a headend. These tests should identify any RF impairments or RF alignment issues within headend, CMTS, EQAMs, modulators, headend amplifiers, splitting and combining network, cables and connectors. Spot checks of the plant should also be performed to ensure the plant is correctly aligned with elements in the headend on both the forward and return.

Parameters such as RF levels, MER, CNR, constellation diagrams, Pre and post Block Errors, group delay, in channel frequency respond, response across all downstream and upstream DOCSIS carriers, upstream band-edge roll off, ingress, noise, impulse noise, CPD, non-linear distortions and laser clipping should be investigated and identified.  The plant should be qualified for DOCSIS and industry specifications where possible and practical.

Where possible broadband audit tests should include the following elements:

  • Proper CMTS / DOCSIS data EQAM operation
  • Proper digital Video EQAM transport operation
  • Proper analog modulator operation
  • Proper test equipment configuration
  • Proper pilot carrier setup
  • Presence of OOB carriers
  • Presence of any test carriers

The following broadband audit tests need to be performed:

  • The forward path RF levels are aligned and balanced correctly feeding all lasers in the headend and hubs from the above elements.
  • Test the forward path RF levels are aligned and balanced correctly from the above elements to EOLs in selected nodes.
  • Check the optical and RF alignment between headend lasers and optical receivers in selected nodes.
  • Test the return path levels throughout the headend from the optical receiver to the CMTS, RPDs and Test equipment.
  • Check and optimize the optical and RF alignment between selected node lasers and headend optical receivers and the CMTS.
  • Test return path levels and other parameters listed above from EOLs, Amplifiers and optical nodes in selected nodes back to the CMTS and RPDs. These tests should include modem transmit parameters as well a source transmitted back to the CMTSs to check headend and plant alignment.

The Volpe Firm will provide a complete broadband audit System Audit Report containing all equipment used, equipment serial numbers (and calibration dates if available), test data, pictures of measurements in progress, identified impairments, corrective actions performed and recommended corrective actions moving forward.

The work breakdown will be divided into two milestones:

  • One will be auditing the downstream, first in the headend to the fiber transmitters and then to the selected node fiber receivers and forward path test points.
  • The second milestone will be auditing the return path.  This will be broken into two subtasks of ensuring proper level at the node return path transmitter and level at the headend receiver.  Next, each return path will be audited to ensure it is compliant to the DOCSIS specification from the node to the CMTS closest monitoring port.