BHI NEDSP900, Руководство пользователя

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NEDSP900 Development Board
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2.3 Balanced input Pre-amplifiers
These can be configured with appropriate gains as required. As mentioned earlier the board is
provided with tracks for these, but they have not been populated. Refer to Appendix B for
further information on the components required for this feature.
2.4 Signal Input selection
There are a variety of ways in which the PCB may be configured for input signals. However, the
section on Gain Settings (section 3) should be read first in order to understand what signals
should be routed to which section of the NEDSP900 module.
Below are some typical signal configurations that may be used.
Channel 1 Channel 2 Comments
Speaker/Headphone/Line Speaker/Headphone/Line
Dual/Stereo Audio input from Radio or recording
Mono Microphone Speaker/Headphone/Line
Communication System for Noisy environments
Balance Audio Signal Speaker/Headphone/Line
Communication System for Noisy environments
Balance Audio Signal Balance Audio Signal Dual/ Stereo balance microphones or signals
2.5 Overload Indicators
Each channel has an Overload indicator (Marked OV’RLD on the PCB) these are located next to
the Power Indicator.
The overload LED’s indicate if the
signals being fed into the NEDSP900
are too high for the device input.
These indicators are set to trigger at
signal levels of 1.4v P-P. The device
is
able to handle over 2 Volts P-P
signal, but above 1.8 Volts the
signal becomes distorted.
Where the single microphone (SK7)
or the balanced input pre-amplifiers are being used, these indicators while monitoring, will not
be effective as the signal will be much lower and you will be relying on the NEDSP900 internal
gain system to increase the levels.
Setting the input level from SK6 Line through to Speaker Level
When inputting signals to SK6, it’s recommended that you have the NEDSP900 Gains set to 0dB.
You should have Jumpers J1 through to J4 set for the expected signal level and impedance. You
can then adjust the input signal level as appropriate for a good audio output. If the Overload
indicators start to flash, then reducing your input signal or change the jumper settings to a