Pre-equalization modem data results are displayed on the Alarm CentralPreEQ tab according to frequency. PreEQ data can be shown for all frequencies or isolated to a single frequency. For each frequency, modems that have been flagged as crossing the Echo Detection Threshold (NMTER) are compared to find similarities. Modems that are sufficiently alike, or meet a comparison threshold, are grouped together into an issue group. Modems in the same group are likely affected by a common issue.
The PreEQ view displays the strength of corrections that are sent to modem equalization traps to compensate for reflected, or echo, transmissions. The Tap Coefficients graph in the PreEQ view shows for each frequency the strength of equalization performed for each tap. You can compare these measurements to discern where in the network transmission energy is reflected and delayed.
The PreEQ view also displays the size of a correction as it occurs in time relative to the main tap. The In-Channel Response graph shows these corrections per frequency and identifies the center channel for each frequency as well as the channel width.