7
3.2.2 Suggested set up procedure:
•
Ensure that the NEDSP1962-KBD module is un-powered.
•
Connect/install the module to an appropriate speaker unit.
•
Connect the speaker to an audio source.
•
Set the source audio to a typical audio level.
•
Press and
hold “Power On/
Off button for around 1 second to power up the module.
The mode LED will light (green for 4 level & Orange for 8 level mode). You will hear
several audio beeps and the LED will flash a same number of times corresponding to the
current noise filter level with the same amount of audio beeps.
•
Make sure that the Overload LED is not illuminating on audio peaks. If it is reduce the
source level audio.
•
Adjust VR2 pot (output level) until the audio sounds about the same level is when the
module was switched off with no power.
•
The module is now set up with no appreciable throughput gain.
•
Adjust the input source to check that the audio output level changes commensurately
and that the Overload LED does not flash.
Note:
For certain situations, the audio may be required to be louder when the module is
powered and carrying out its DSP function. In this case, carry out the above procedure and
adjust VR2 to give you increased audio output. Bear in mind that if the user may get a bit of a
shock when the module is powered, and the volume suddenly changes from a normally
acceptable level to one that’s
quite loud.
3.2.3 Other signal considerations
Due to the adaptive nature of the noise reduction algorithm, a small delay may be heard
between any input audio changes and the action of the Noise Reduction algorithm, especially
when the input signal disappears then re-appears or the input signal become clear of noise and
then gets noisier. Under these circumstances the algorithm needs to adapt to the signal and this
can take about 20mS to 100mS. For optimum performance the input signal should be applied
constantly where possible.
Upon powering up or switch-on a very quiet thump of click may be heard in the loudspeaker.
This is due to the amplifier being enabled and is normal behaviour.
3.2.4 Beep Tone level
The beep tones volume can be adjusted VR3. Once the audio level is set up, and if the function
beeps are required, these may need setting to an appropriate level. This can be carried out by
adjusting VR3 ‘Beep’. Clockwise will increase the level, Anti
-clockwise will reduce the level. If
the beeps are not required, then VR3 can be set fully anti-clockwise or the solder link across
JP16 may be removed using solder wick and a fine soldering iron tip.
