Wildlife Acoustics sm3bat, Руководство пользователя

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Developing Custom Programs SM3BAT User Guide
page
40
BIOACOUSTIC MONITORING SYSTEMS
6.3
Program Commands
Use the following commands to create programs for your specific recording
needs. A program can contain up to 99 command lines.
NOTE : Some commands listed in this section refer to sunrise or sunset in a general
sense and depend on them in program calculations. The recorder recognizes different
methods for calculating precise sunrise and sunset times. To specify a method and
view the next available sunrise and sunset times, select Sunrise/Sunset Type in the
Settings menu.
HPF {OFF,220HZ,1KHZ,16KHZ} {OFF,200HZ,1KHZ,16KHZ}
This sets the channel 0 and 1 analog high pass filter. A high pass filter only
allows signals higher than the specified frequency to be recorded. For
recording very low frequency sounds such as elephants, set this to OFF .
Otherwise it is useful to cut down on wind and anthropogenic noise and
should be set to at least 220 Hz. If your signals of interest are higher, it is
better to go even higher.
The filter is a two pole filter, meaning it attenuates sounds at 12dB per
octave. So if set to 1.0 kHz, a 500 Hz sound would be attenuated by 12dB.
Every 6dB represents a halving of sound level, so the 500 Hz sound would
appear in the recording at one-fourth (
¼
or 0.25
)
its original amplitude.
For bats, the SMM-U1 microphone has a built-in 4-pole filter at 8 kHz. If you
expect bats vocalizing below 16 kHz, set this HPF to 1 kHz and the 8 kHz
filter in the microphone will reduces acoustic sound below 8 kHz. If you do
not expect bats below 16 kHz, it is best to use set this to 16 kHz and filter
out more acoustic noises that might cause non-bat recordings to occur.
GAIN <gain-channel-0> <gain-channel-1>
Analog voltage gain settings. The range is 0 dB to 59.5 dB in 0.5 dB steps for
acoustic sample rates (96 kHz or below) or 0 dB or 12 dB for ultrasonic
recordings. Gain has Auto selection available.
For bats, we recommend 12 dB unless the bats are very close in which case
0 dB might work better.
Gain
AUTO
setting behavior:
■
Internal or external acoustic microphone on the channel: 24 dB
■
External hydrophone on the channel: 0 dB
■
Ultrasonic microphone on the channel: 12 dB
TIP : If your recordings are too loud or distorted, try decreasing the GAIN value.