Difference between revisions of "AudioMoth"

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(Suggested trigger extension)
 
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   {{Project
 
   {{Project
 
   |Name=AudioMoth
 
   |Name=AudioMoth
   |Status=Initializing
+
   |Status=In progress
   |Picture=whyunopicture.png
+
   |Picture=audiomoth.png
 
   |Contact=bertrik
 
   |Contact=bertrik
 
   }}
 
   }}
  
 
== What ==
 
== What ==
I plan to buy an AudioMoth board, and improve its software:
+
I have an AudioMoth board, and plan to improve its software:
 
* https://www.openacousticdevices.info/
 
* https://www.openacousticdevices.info/
 
* https://github.com/OpenAcousticDevices/AudioMoth-Project source code
 
* https://github.com/OpenAcousticDevices/AudioMoth-Project source code
 +
 +
Ideas:
 +
* general clean-up
 +
** fix white space, remove many of the empty lines (earlier CR/LF mistake?), like these https://github.com/bertrik/AudioMoth-Firmware-Basic/blob/master/main.c#L154
 +
** fix sprintf statements, like these https://github.com/bertrik/AudioMoth-Firmware-Basic/blob/master/main.c#L167
 +
** fix complicated and non-portable casts (sensitive to endianness), like this https://github.com/bertrik/AudioMoth-Firmware-Basic/blob/master/main.c#L161
 +
* update tool-chain to newer version
 +
** update gcc
 +
** attempt to make it possible to compile with platformio
 +
** document it and upstream it when it works
 +
* extend functions
 +
** add trigger functionality, maybe a specific bat trigger (high pass filter)?
 +
** crest (instantaneous vs average) trigger?
 +
** save files in sub-directories (per day) instead of a flat filesystem?
  
 
== Hardware ==
 
== Hardware ==
 +
[[File:SPM0408LE5H_response.png|thumb|right|Frequency response]]
 +
 
See https://circuithub.com/projects/OpenAcoustics/AudioMoth
 
See https://circuithub.com/projects/OpenAcoustics/AudioMoth
  
* microphone is SPM0408LE5H, [https://www.mouser.com/datasheet/2/218/-532499.pdf datasheet]
+
The microphone is a [https://www.mouser.com/datasheet/2/218/-532499.pdf SPM0408LE5H].
* processor is EFM32WG380F256, [https://www.silabs.com/mcu/32-bit/efm32-wonder-gecko/device.efm32wg380f256-qfp100 link]
+
Can't find much about its ultrasonic performance. The official graph shows a hint of resonance above 10k so it does have ultrasonic sensitivity.
 +
For frequencies higher than the resonance peak the response of a typical microphone drops off steeply with 6 dB/octave.
 +
I have been able to record some pipistrelle bats with it (40 - 50 kHz).
 +
 
 +
The processor is EFM32WG380F256, [https://www.silabs.com/mcu/32-bit/efm32-wonder-gecko/device.efm32wg380f256-qfp100 link]
 +
 
 +
Where is the schematic?
  
 
== Software ==
 
== Software ==
 
My fork on github: https://github.com/bertrik/AudioMoth-Project
 
My fork on github: https://github.com/bertrik/AudioMoth-Project
 +
 +
=== Suggested trigger extension ===
 +
A bat specific trigger is desireable because this way we only get "interesting" files.
 +
 +
The idea is that bat signals are, in general:
 +
* ultrasonic, frequency above 10 kHz
 +
* organised in short pulses, e.g. 8 pulses per second of 5 ms each for a pipistrelle
 +
Challenges:
 +
* crickets, sound is also at least partly ultrasonic, overlapping with the calls of some of the larger bats and with social bat calls in general
 +
 +
Proposed algorithm:
 +
# Apply a high-pass filter at about 10 kHz, this needs not be super-sharp filter. Perhaps just a simple 1-pole IIR (easy to calculate).
 +
# Calculate the energy in each millisecond by summing the squared amplitude of the high-pass filtered signal over this millisecond. Perhaps we can also just calculate variance here and forget about step 1).
 +
# Calculate a running average energy over several (say 500) of these milliseconds values.
 +
# If the millisecond energy exceeds the average energy by a factor X (the sensitivity of the trigger) for a duration of Y consecutive milliseconds, consider the trigger to be active.
 +
 +
=== Running the tools ===
 +
Running the AudioMoth tools (configuration tool, flash tool, etc) requires the --no-sandbox option (at least on my system), for example
 +
  ./AudioMothConfigurationAppSetup1.2.5.AppImage --no-sandbox
 +
 +
=== IDE for development ===
 +
A description of all steps to get the firmware compiled is written here:
 +
https://github.com/OpenAcousticDevices/AudioMoth-Project/wiki/AudioMoth
  
 
=== Compiling ===
 
=== Compiling ===
 
==== platformio ====
 
==== platformio ====
 +
It compiles and produces a firmware.bin file, but it's not recognized by the flashing tool as a valid file.
 +
 
Use this platformio.ini file:
 
Use this platformio.ini file:
 
   [platformio]
 
   [platformio]

Latest revision as of 11:43, 7 April 2021

Project AudioMoth
Audiomoth.png
Status In progress
Contact bertrik
Last Update 2021-04-07

What

I have an AudioMoth board, and plan to improve its software:

Ideas:

Hardware

Frequency response

See https://circuithub.com/projects/OpenAcoustics/AudioMoth

The microphone is a SPM0408LE5H. Can't find much about its ultrasonic performance. The official graph shows a hint of resonance above 10k so it does have ultrasonic sensitivity. For frequencies higher than the resonance peak the response of a typical microphone drops off steeply with 6 dB/octave. I have been able to record some pipistrelle bats with it (40 - 50 kHz).

The processor is EFM32WG380F256, link

Where is the schematic?

Software

My fork on github: https://github.com/bertrik/AudioMoth-Project

Suggested trigger extension

A bat specific trigger is desireable because this way we only get "interesting" files.

The idea is that bat signals are, in general:

  • ultrasonic, frequency above 10 kHz
  • organised in short pulses, e.g. 8 pulses per second of 5 ms each for a pipistrelle

Challenges:

  • crickets, sound is also at least partly ultrasonic, overlapping with the calls of some of the larger bats and with social bat calls in general

Proposed algorithm:

  1. Apply a high-pass filter at about 10 kHz, this needs not be super-sharp filter. Perhaps just a simple 1-pole IIR (easy to calculate).
  2. Calculate the energy in each millisecond by summing the squared amplitude of the high-pass filtered signal over this millisecond. Perhaps we can also just calculate variance here and forget about step 1).
  3. Calculate a running average energy over several (say 500) of these milliseconds values.
  4. If the millisecond energy exceeds the average energy by a factor X (the sensitivity of the trigger) for a duration of Y consecutive milliseconds, consider the trigger to be active.

Running the tools

Running the AudioMoth tools (configuration tool, flash tool, etc) requires the --no-sandbox option (at least on my system), for example

 ./AudioMothConfigurationAppSetup1.2.5.AppImage --no-sandbox

IDE for development

A description of all steps to get the firmware compiled is written here: https://github.com/OpenAcousticDevices/AudioMoth-Project/wiki/AudioMoth

Compiling

platformio

It compiles and produces a firmware.bin file, but it's not recognized by the flashing tool as a valid file.

Use this platformio.ini file:

 [platformio]
 src_dir = src,fatfs_src
 include_dir = inc,fatfs_inc
 [env:default]
 framework = zephyr
 platform = siliconlabsefm32
 board = efm32wg_stk3800

Install platformio:

 sudo apt install python3-pip
 sudo pip3 install platformio
 sudo pip3 install -U PyYAML

Compile it:

 pio run