Vortex Ef2280 Inputs And Outputs - Polycom EF2201 Brochure & Specs

7
7
V
V
The Vortex EF2280 has 12 analog inputs: 8 mic/line inputs and 4 line inputs, and 12 line-level analog outputs as shown in
All inputs and outputs are actively balanced.
Input level control (before the A/D converter) is executed in the analog domain using digitally controlled analog trim pots. This
approach was taken to maximize the signal to noise ratio of the system – the A/D always gets the proper level to create the best
sounding digital signal that is possible. The microphone switch provides 33 dB of gain and the software controlled analog level
adjust can provide up to an additional 30 dB of gain on channels 1-8.
Phantom
Inputs 1 to 8
Mic/Line
Figure 8. The input signal chain for inputs 1 to 8.
Mic/Line Inputs 1-8
Balanced audio appears at the rear panel mini Phoenix™ connector (3.5mm spacing). Microphone or line level is selected and
phantom power can be enabled or disabled. As shown in Figure 8 the level adjustment to match the nominal level of the
microphones is performed in the analog domain – this ensures that the signal to noise ratio of the signal is preserved. Once the
proper gain is set for the input channel (this step is done in calibration), the signal is ready to be converted to the digital domain
through the A/D converter.
Once the input signal is converted to a 24-bit digital signal, it is converted to a 32-bit floating-point number and presented to the
processing blocks. When viewing the input signal meter on the Vortex front panel or through the Conference Composer software,
the input meter shows the signal strength just after the input channel has been converted to a digital signal (right after the A/D
converter). The Vortex uses floating-point arithmetic to maintain the highest signal to noise ratio possible through the processing.
The first processing block is the acoustic echo canceller (AEC) which, if enabled, will eliminate the acoustical coupling of the
remote talkers' speech from being coupled back into the microphone and sent back to the remote talkers. The AEC can use one of
three reference signals: Ref 1, Ref 2, or the EF Bus external reference. Ref 1 and Ref 2 can be built from any of the input signal by
using the main matrix. The AEC reference should contain the appropriate mix of remote talker signals (such as the codec audio and
phone add audio) with the local program audio. Local sound reinforcement should not be added into the reference. Integrated
within the AEC is the noise cancellation processing which will analyze the signal and remove steady state random noise from the
signal. The user can select various levels of noise cancellation from 0 to 15 dB with 10dB the default value.
20
E F 2 2 8
E F 2 2 8
O R T E X
O R T E X
Level
adjust
A/D
-
AGC
On Off
0 I
0 I
N P U T S A N D
N P U T S A N D
Echo Noise
Canceller Canceller
Parameters
Ref 1, Ref 2, Bus
PEQ Mute
On Off
Parameters
O
O
U T P U T S
U T P U T S
Figure 2
To Matrix
Gate
Parameters
.