9
3.0 STANDARD FILTER CONFIGURATIONS
3.1 Preprogrammed Filter Setups
The filters in the standard PicoDAC are optimized for noise cancellation to increase voice
intelligibility. Simple noises are generally greatly attenuated. However, more complex
noises such as those from bars or automobiles can only be modestly attenuated. The
table below shows the characteristics of the filter selected by the front panel
FILTER
selector switch.
FILTER
Switch
Setting
Bandwidth
(kHz)
Adaptive Filter Size - Stage 1
(Noise Type)
Filter Type- Stage 2
0
3.4
Medium (Normal Setting)
High Pass (300 Hz)
1
3.4
Large (Complex Noises)
Adaptive (Small)
2
5.0
Small (Simple Tones)
High Pass (300 Hz)
3
5.0
Medium (Normal Setting)
High Pass (300 Hz)
4
5.0
Large (Complex Noises)
High Pass (300 Hz)
5
5.0
Large (Complex Noises)
Adaptive (Small)
6
7.5
Small (Simple Tones)
Band Pass (300-5000 Hz)
7
7.5
Medium (Normal Setting)
Band Pass (300-5000 Hz)
8
7.5
Large (Complex Noises)
Band Pass (300-5000 Hz)
9
7.5
Large (Complex Noises)
Adaptive (Small)
Table 1: Standard Filter Configuration
The
FILTER
switch setting determines the signal bandwidth and type of filtering based
upon the configuration programmed into the PicoDAC. When in the
BYP
mode, the
PicoDAC simply bandlimits any audio applied to the
INPUT
connector and sends it to the
OUTPUT
connector, bypassing the audio filters.
The ten standard filter configurations consist of three different adaptive filter sizes (small,
medium, and large) at three bandwidths (3.4, 5.0, and 7.5 kHz) followed by either another
small adaptive filter or bandlimiting filter (bandpass or highpass). The selected
combinations of filter bandwidths and sizes allow the operator to easily customize the
PicoDAC to a wide range of noise removal situations as explained in the following section.
