Orca

Links

frequency counter using RP2040 - https://iosoft.blog/2023/08/21/picofreq_python/

2 channel A/D (stackable) - https://community.element14.com/products/roadtest/rv/roadtest_reviews/1582/sound_measurement_an

6 channel ADC - https://www.pishop.us/product/6-channel-esp32c3-adc-hat/

Pair RPi to Android - https://bluedot.readthedocs.io/en/latest/gettingstarted.html

Bluetooth

Starting with this link, https://grandorimichael.medium.com/setting-up-a-raspberry-pi-to-send-nmea-messages-via-bluetooth-to-atak-for-external-gps-integration-07e7f8bf3048

This is the summary:

sudo apt install bluetooth pi-bluetooth bluez blueman