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Managing Deployments SM3BAT User Guide
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BIOACOUSTIC MONITORING SYSTEMS
7 Managing Deployments
Recording time is determined by the demands of your program and the available
power and memory resources required to carry out the recordings. The SM3BAT
can only record while it has sufficient power available in the batteries and room to
save recordings on SD memory cards. Download our free SM3 Configurator
software application to see detailed visual forecasts for remaining battery life and
memory card utilization given your specific recording schedule and configuration.
7.1
How to Estimate Battery Life
In sleep mode between scheduled recordings, the SM3BAT uses almost no power
(around 0.5 mW) so it can remain idle (not recording) for months at a time.
However, the batteries will discharge on their own over time. When recording,
depending on accessories, sample rates, compression, and other variables, the
SM3BAT can use as little as 500 mW power. That translates to up to 2 weeks of
nightly recording using high-quality alkaline batteries. Use the SM3 Configurator
to estimate a recording schedule based on your program requirements.
7.2
How to Estimate Memory Requirements
7.2.1
Ultrasonic Recording
In a typical night with bat activity (and no rain or gusty wind), you need about 0.5
GB for a stereo recording. Even with gusty wind causing false triggers, you only
need about 2.0 GB per night. In WAV mode, since files are scrubbed for non-bat
recordings, you need even less. A 32 GB card can last for 2-8 weeks. In zero
crossing mode, you can expect a 32 GB card to last for months if not years.
7.2.2
Acoustic Recording
Acoustic recordings without triggers consume 2 bytes (16-bits) per sample, times
the sample rate, times the number of channels per second. For example, a
recording made at a sampling rate of 24,000 samples per second in stereo (2
channels) consumes 2 x 24,000 x 2 = 96,000 bytes per second. With 128 GB total
capacity, an SD memory card of this size can record up to 128,000,000,000 divided
by 96,000 = 1,333,333 seconds, or about 370 hours of recording time.
NOTE : The largest recording file size allowed is 2.0 GB. The recorder automatically
breaks up large recordings into smaller segments to satisfy this requirement.