Refer to Measure Sweep Overview for an explanation of system sweep and
the functioning of the sweep components. "Sweeping" detects
many problems. Used efficiently, a sweep system can detect "suckouts"
(sudden drops in frequency response) and other narrow frequency response
irregularities.
FORWARD SWEEP (Optional Purchase Required)
Forward sweep uses a headend transceiver to measure carrier levels and,
when necessary, to inject short sweep pulses. When stable carriers are
present, they can be referenced to create a sweep response without injecting
any sweep pulses. This minimizes any subscriber interference as a result
of sweep testing.
In Forward Sweep the headend transceiver communicates with the field DSAM
by telemetry transmitted on a forward frequency. The telemetry provides
the sweep level results, as measured in the headend, downstream to the
DSAM which compares the results to the local sweep results. The final
display is the difference of the two measurements resulting in a delta
graph. A reference file is captured typically at the node amp output before
moving to the next amp. The following sweeps use the reference file to
null out any differences that could not be corrected at the node. The
ideal sweep results at the output of each amp will be a flat response
graph centered at 0 dB delta reference, assuming the goal is zero gain
across the entire distribution network.