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AM-55 / Sep 2015
A M - 5 5 G U I
Automatic Input Failover
In the event the currently selected input source fails and the Automatic Input Failover
check box is checked, an alternate source of audio which has been connected to the
other audio input can automatically be put on the air.
If the primary source was digital, the analog input will be selected immediately
if there are invalid bits in the data stream or missing audio data. Also, the analog
input will be selected after 30 seconds of a valid digital data stream having
signal levels below ‑42dBFS.
If the primary source was analog, then a silence sense timeout of 30 seconds
must elapse before the unit switches to the digital input. The audio failure sense
threshold is fixed at ‑42dBFS, and this combination with the 30 seconds timeout
is suitable for virtually all program types.
NOTE:
The input failover option can only switch between an analog input and a
digital input. Failover from WheatNet‑IP to AES/EBU (or vice versa) is not supported.
Input Level Control
There are two sets of input controls. The controls that are displayed are the
ones for the active input. As you can see to the right, the analog controls are
shown since the audio source selected in Analog Line In. The Analog audio
input gain can be adjusted by clicking on the knob and dragging the mouse
or touchpad to the right or left. The Analog Gain level can be adjusted over a
range of +/‑ 12dB.
If one of the digital inputs were selected,
the input level control would show the cur‑
rent left and right gain for that control. The
same goes for WheatNet‑IP. Each input can
have its own gain
The AES/EBU and WheatNet‑IP Digital audio
input gain can be adjusted by clicking on the knob
and dragging the mouse or touchpad to the right
or left. The Digital Gain can be adjusted over a
range of +/‑ 12dB.
Input Polarity
Input Polarity
check box switches input’s absolute polarity.
Phase Rotator
Human voice is usually asymmetrical by nature, which means that it is
usually “peakier” in one polarity than the other, hence asymmetrical. What
the Phase Rotator algorithm does is fix these asymmetrical peaks. The way
it works is by phase shifting the signal harmonics relative to their fundamen
‑
tal frequencies. This action reduces the peak to average ratio and enables
an increase in apparent loudness with minimal audible detriment. We do this because
processing the audio is greatly simplified if the waveforms are symmetrical.
