A low-cost, self-build, frequency-scanning heterodyne bat detector with full-spectrum field recorder function
Hardware features :
Processing by Raspberry Pi Pico, dual-core 133MHz ARM Cortex-M0
Powered by 5V USB powerbank or 3x AA cells
Knowles ultrasonic microphone sampled at 384kHz
High frequency op-amp
Optional LM4040 voltage reference for improved ADC performance
On-board 10kHz high-pass filter for LF / interference / speech suppression
10-LED real-time spectrum display
Micro SD card interface
Detector mode :
'Eyes to the skies' operation - largely hands-free interface with auto-frequency scanning, audio feedback on bat frequency detection, allowing user to track and ID bats visually
Speech synthesiser for frequency and bat ID feedback
Twin headphone jacks for simultaneous listening and recording, or paired listening
Manual override of heterodyne frequency via rotary controller
Recorder mode :
Overnight / multi-night unattended field recording
Burst 5s recordings, triggered by ultrasonic signal detection
Device low power mode during non-bat hours
Storage capacity limited by SD card size - 8GB typically good for 2 nights' recording
iPhone / iPad app sets date and time prior to entering low power mode for accurate time logging of survey recordings
Build cost for 10-off units (late 2001) :
'Detector' configuration : Under £13.00 per unit
'Recorder' configuration : Under £20.00 per unit (recorder includes Adafruit SPI SD breakout plus SD card)
Hardware features :
Processing by Raspberry Pi Pico, dual-core 133MHz ARM Cortex-M0
Powered by 5V USB powerbank or 3x AA cells
Knowles ultrasonic microphone sampled at 384kHz
High frequency op-amp
Optional LM4040 voltage reference for improved ADC performance
On-board 10kHz high-pass filter for LF / interference / speech suppression
10-LED real-time spectrum display
Micro SD card interface
Detector mode :
'Eyes to the skies' operation - largely hands-free interface with auto-frequency scanning, audio feedback on bat frequency detection, allowing user to track and ID bats visually
Speech synthesiser for frequency and bat ID feedback
Twin headphone jacks for simultaneous listening and recording, or paired listening
Manual override of heterodyne frequency via rotary controller
Recorder mode :
Overnight / multi-night unattended field recording
Burst 5s recordings, triggered by ultrasonic signal detection
Device low power mode during non-bat hours
Storage capacity limited by SD card size - 8GB typically good for 2 nights' recording
iPhone / iPad app sets date and time prior to entering low power mode for accurate time logging of survey recordings
Build cost for 10-off units (late 2001) :
'Detector' configuration : Under £13.00 per unit
'Recorder' configuration : Under £20.00 per unit (recorder includes Adafruit SPI SD breakout plus SD card)
