This instructable was written by Anthony Turner. The project was developed with lots of help from the Shed in the School of Computing, University of Kent (Mr Daniel Knox was a great help!).
It will show you how to build an Automated Audio Recording Unit for less than £150. You can use this unit to conduct research in the field of Soundscape Ecology (which is why I built this). You could use it to monitor the birds in your garden or just to make nice recordings of the dawn chorus, without having to get up really early.
The ARUPi (Automated Recording Unit Pi) uses the Raspberry Pi computer and an Arduino-based power-control board called the Sleepy Pi. It is fully customisable and you will be able to add different environmental sensors to the units if you wish (not explained here). This instructable will give you a bare-bones unit. I will provide you with an Arch Linux operating system (OS) that is stripped down and has the recording program pre-installed on it.
You may need to do some (very simple) soldering so be prepared for this, but it is possible to build this unit without soldering if you do not own or cannot afford a soldering iron (ca. £10). I will split this instructable into several steps. The first ## steps will deal with getting the software onto your ARUPi and getting the computer side of things up and running (uploading software to Raspberry Pi and Sleepy Pi). Once you have done this, you will be able to go your own way and decide which microphones and casing you want to use. If you want to make what I have made, then continue with the instructable and it will show you how to build some cheap (but good) microphones and assemble some field-tested, fully waterproof, pretty robust ARUPi's (pictured).
NB: for a more detailed list of parts, see note at end of Step 2
1. Raspberry Pi A+ (case optional) - get it from PiMoroni/Ebay/Amazon
2. Sleepy Pi - http://spellfoundry.com/products/sleepy-pi/
3. Sleepy Pi programmer - http://spellfoundry.com/products/sleepy-pi-program...
4. 16GB Kingston Data Traveler Micro (pictured). You need to format the USB drive to NTFS before plugging it into your Raspberry Pi (format USB using Windows Explore - see image). If you decide to use a different make/model/capacity USB storage device, you may need to change some information in the /etc/fstab system files on the ARUPi OS I supply you with. The OS I provide you with mounts the 16GB Kingston Micro DT to sda1 (the kingston Micro DT 64gb usb drive mounts to sda5 - you need to alter these in the fstab folder, but that is included in the instructions a bit later on). Whichever USB drive you go with, make sure you use the same one each time you change it in your completed ARUPi when out in the field - the ARUPi will not automatically recognise a new USB drive.
5. USB soundcard. I chose the Creative Soundblaster Play! because it records 16bit Stereo up to 48KHz. It is also compatible with the Raspberry Pi and doesn't need any extra drivers - plug and play. However, there are cheaper USB soundcards available so it might be worth investigating.
6. USB splitter. The one pictured works well and is available on Ebay from multiple sellers. It is slightly less bulky than others that are available (but it is still rather big - but it is more bendy so fits inside my waterproof enclosure well).