9
4.1.1 Power button
The power button toggles the module On and Off. When the power is
“
Off
”
the audio bypasses
straight through the module directly to the output speaker, so the circuit will behave as if the
module isn’t present. Switching the power “
On
”
routes the audio through the module.
Note:
If the Power is On and the DSP is switched Off, the audio still passes through the DSP
processing circuitry, which creates a bandpass filter with Upper and Lower cut-off frequencies of
200 Hz and 5000 Hz.
A single press of the Power button for about 1 second switches the module On, and a further
single press of around 1 second will switch the Module Off.
With the power connected and the module switched Off the circuit will still draw approximately
6mA.
4.1.2 DSP Level Button
This function button is used to set the following:
•
DSP filter On/Off
•
DSP Noise Reduction level change
•
4 or 8 Levels of Noise Reduction
4.1.3 Noise Reduction Levels
4 or 8 levels of Noise Reduction available. The amount by which any Noise and Tone signals
are reduced are shown in Table 4 below:
Level
(4)
Level
(8)
Heterodyne Reduction
White Noise
Reduction
1
4dB
8dB
1
2
5dB
12dB
3
6dB
16dB
2
4
8dB
20dB
5
16dB
25dB
3
6
21dB
30dB
7
25dB
35dB
4
8
65dB
40dB
Table 4 above. Heterodyne and Noise reduction levels
The column marked (4) shows the noise and tone reduction when operating the module in 4
level mode, and the level (8) column for 8 levels. The 4 level mode gives you bigger changes
between the filter levels.