ClearOne comm XAP 400 Filters, System Configuration ~ Inputs and Outputs, Meters, Active Filter

System Configuration ~ Inputs and Outputs 35

Non-linear Processing (NLP)

The Non-linear Processing (NLP) feature increases the power of echo cancellation for difficult acoustical environments. NLP features four settings: Soft (6dB), Medium (12dB), Aggressive (18dB), and Off. Use NLP with care; corresponding trade-offs can include suppression and half-duplex operation. Default is Soft.

Meters

The Echo Return Loss (ERL) meter on the Acoustic Echo Canceller window shows the coupling between the reference signal and the input to the echo canceller—the ratio of the two levels. It is an average meter that updates only when a signal is present.

The Echo Return Loss Enhancement (ERLE) meter shows the loss through the echo cancellation and non-linear processing chain—the ratio of the two levels. It is an average meter that updates only when a signal is present.

The Total Echo Reduction meter shows the total ERL and ERLE reduction, in decibels. It is an average meter that updates only when a signal is present.

NC

The NC button on the selected input in the Inputs 1–4 window opens the Noise Canceller window. The noise canceller reduces ambient noise in the signal with no noticeable degradation in signal quality.

To use noise cancellation, click Enable Noise Canceller, then adjust the Cancellation Depth to the setting which provides the best combination of low noise and maximum speech clarity. The attenuation depth can be set in 1dB increments from 6dB to 15dB. Default is 6dB.

Figure 3.32. Noise Canceller window

The noise canceller default is Off. When noise cancellation is enabled, the light on the NC button illuminates green.

Filters

The Filter button on the selected input in the Inputs 1–4 window opens the Filter Graph setup window. Each mic/line input has four configurable filters that can be used as filters or equalizers. By default, they are not enabled and the filter types are not defined. Below is a description of each feature in the window.

Active Filter

Active Filter selects among filters on the graph. Note that no filters exist until you click Add Filter (see Figure 3.33) to add filters to the graph.

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