BHI NEDSP900, Руководство пользователя

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NEDSP900 Development Board
10
When experimenting with the Noise Reduction levels, start with the lowest level and then increase the
‘Strength’ until you find a satisfactory level which is providing the necessary Noise Reduction without
making the audio distorted or ‘watery’ where the audio artefacts sound like dripping water. This has a
lot to do with the type of noise you are trying to combat as much the level of Noise Reduction.
Once you have found a suitable Noise Reduction level, note the value for future reference.
You can get a feel for how much clearer the Noise Reduction is making the signal by switching the DSP
OFF and then back ON again.
Note: the DSP algorithm may take a short while to take full effect, approximately 500 mS, dependent
on the noise content of the signal.
While playing with the Noise Reduction you may find that you have to increase the appropriate Output
Level control as the effect of the Noise Reduction is to reduce the mean audio level so that everything
sounds quieter. This is mainly because the noisy parts of the signal are being removed to improve the
overall speech quality of the signal.
5.0
Outputs
There are two outputs available. One is provided to allow recording of results or for onward audio
processing. The other is capable of driving a small speaker system or headphones. Each output is
independently adjustable via the two edge mounted controls.
Users should be aware that as these are wired for Stereo Output. Monaural jack plugs should not be
used as this could cause damage to the circuitry. If a mono output is required it is recommended that
stereo jack plug is used with just the required channel wired. If in doubt, consult bhi Ltd.
5.1 Line Drive
This is capable of driving up to 1 Volt P-P into a 600 Ohm (resistive) load and can drive as high as
2Volts p-p into higher
impedances. The gain of this output stage is fixed and the signal level is set by
potentiometer R1 a & b located adjacent to SK3 which is the output socket.
SK3 – Line Output
SK3 – Line Output
Level Control
SK10 – Headphone/
Speaker
Output
R1a&b – Headphone
/Speaker Level Control