Operation Manual

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ASPI Digital - The Sound of DSP Technical Support: 404.892.3200 27
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ALIBRATION
For the EF1210 to work effectively, it must be calibrated properly to receive correct
levels from the surrounding equipment, such as microphones, amplifier, and CODEC.
The calibration procedure is required only to adjust the EF1210 to accommodate the
electrical characteristics of your conferencing equipment. The procedure allows you
to connect the widest possible variety of equipment to your EF1210. It does not train
the AEC. The EF1210 does not require training.
In calibration mode, the EF1210 generates a precise noise signal for measuring the
characteristics and sensitivity of the microphone. You only need to perform this cali-
bration at the initial installation. You do not have to calibrate the EF1210 each time
it is used.
Calibration Steps
• Calibration Step 1: Calibrating Microphone Input Channels (page 29)
• Calibration Step 2: Calibrating Zone Outputs, Check Acoustic Gain (page 30)
• Calibration Step 3: Calibrating AEC Reference Inputs (page 32)
• Calibration Step 4: Calibrating for Playback and Record (page 33). This step
may be skipped if you are not using playback and record on the EF1210.
• Calibration Step 5: Zone/Reference Setup (page 34)
Acoustic Gain
Acoustic gain is the maximum amplification that may be applied to a room’s audio
before being picked up by the microphone(s). The volume control may be set at a
lower level than this maximum amplification, but must not be set higher. Too much
acoustic gain occurs if the loudspeaker volume going into the microphone is louder
than the local talker’s volume. This may happen as a result of a combination of the
following setups: the loudspeaker volume is turned up too much, the microphone
level is too high, the microphone is too close to the loudspeaker, or the talker is not
talking close enough to the microphone relative to the loudspeaker volume. Acoustic
gain is commonly misunderstood, so when the audio in a room is not loud enough, it
seems logical to turn up the volume on the amplifier or loudspeaker. This is often not
the best remedy. For example, it may be necessary to turn up the reference input level
instead. Breaking through the acoustic gain threshold can cause echoes and howling
as loudspeaker levels overpower the microphones.
The calibration procedure will outline how to associate a volume level with the acous-
tic gain of a room. Refer to “Check Acoustic Gain” on page 31.
Note.
When calibrated for the particular microphone and CODEC
setup, the EF1210 will provide years of service without recalibra-
tion. If the signal levels are not calibrated, the performance of the
EF1210 will not be satisfactory. When the signal levels are cali-
brated correctly, the EF1210 easily and automatically handles any
type of signals and changes in room acoustics to provide unparal-
leled echo cancellation performance.
Note.
If you decide to use a different kind of microphone once the
EF1210 has been calibrated, the microphone inputs on the
EF1210 will be need to be recalibrated.