I am truly amazed at how the microcontroller Gecko EFM32 contained on the AudioMoths and variants can do so much in so little space. In my original search for a platform that could have high sample rates, I was at a dead end and faced with buying a very expensive DAQ recorder. Then a friend told me about the AudioMoth that can do high sample rates. Simple solution. But I wondered what allowed a very small device to to this? Some other more expensive platforms now being sold have ARM chips in them, but the Gecko does too.
https://www.silabs.com/mcu/32-bit-microcontrollers/efm32-gecko
I am not a computer science nerd, but do wonder exactly how the AudioMoth can perform such high sample rates? Is it just the Gecko or are other components on the board doing the job? If so which components?
At 384kHz the dynamic range of the audio is 12-bits as this is the raw resolution of the ADC. With each halving of the sample rate you get an extra bit up to the 16 bits maximum of the WAV file. Quality is very subjective and depends on the application.
Most audio recorders use external analog-to-digital converters (ADC) to generate the audio samples. These often have built-in audio filters and are optimised for particular sample rates, typically 48kHz, and often 192kHz at most. AudioMoth does everything through the Wonder Gecko's internal op-amps and ADC. This is slightly lower quality, and has a lower bit resolution, but gives much more flexibility. We generate raw 12-bit audio samples at 250kHz or 384kHz, and then downsample and filter these in software.