NAUTA scientific, a partner in this project, has prepared two types of recorders, which use two different sensors and acquisition circuits.
The first is the commercial underwater recorder called uRec 384k. It uses a Sensor Technolgy SQ26-05 hydrophone as the sensor, which is sensitive from a few hertz up to over 60kHz. The recording board used is a customised version of the Ultramic384 recorder designed and manufactured in Italy by Dodotronic.
Everything, including the necessary batteries, is housed inside an 8cm outer diameter cylinder made of transparent acrylic resin, with 1cm of wall. Two delrin screw caps guarantee a watertight seal.
The second prototype realised for the project is based on Aquarian Audio’s H2c hydrophone. This is a cheaper, less high-performance sensor, but whose performance in a ‘professional’ task such as this project is interesting to evaluate.
In this second project, a recording card that has been very popular in recent years was used: an AudioMoth.
Sampling rate / Sampling frequency: up to 384kHz, but in TURSIONET we will use 192kHz
Frequency response of the recorder / frequency response of the recorder for 192kHz sampling: from 10Hz up to about 90kHz
Gain / gain of the preamplifier: use 1x (NO GAIN), the two small switches should both be OFF
Power supply / power supply: USE 3x (SIZE D) standard alkaline NOT rechargeable batteries.
Batteries should be controlled periodically and should be replaced when the battery tester indicates WEAK (battery tester is supplied with the recorder)
Memory: use the 256GB card provided
Real-time clock / RTC / Internal clock: is powered by the small button battery beside the memory card. Need to synchronize it with the phone when programming.
The standard hydrophone is either a Sensor Technology SQ26-05 or an Aquarian Audio H2c, used for comparative tests.