Long-term Recorders

From EARWiki

One possibility is using embedded computers. These are very small computers, with several limitations, like the ones in cars. Gumstix makes the smallest ones that have audio capabilities and large storage capacity. The main boards are the size of a chewing gum (gumstix). They have three lines of computers, differing in processor speed and bluetooth capability, plus many accessory cards, like:

• audio card with mini-stereo plugs for audio input and output
• another audio card with a GPS module
• CompactFlash adapter
• Wifi adapter
• Ethernet adapter

Newer cards can use USB devices, so if Internet connection is not available, the system can store the files in an external USB drive. Current laptop drives (2.5") can store up to 200GB.

Battery Life

A small test of battery life using two configurations:

• Gumstix on all the time
  • Records a 60 sec 48 kHz stereo wav file, saves it and records another one. About 1-2 seconds between files.
  • Files saved to a CF card
  • Battery: Li-Ion 3.6 V 7200mAh
  • Voltage controlled to 4V using a switching converter
  • Total recorded: 1800 files (~30 hours)

• Gumstix turned on and off by a picaxe microcontroller, with processing of the file
  • Records a 60 sec 48 kHz stereo wav file, converts to mono, and compresses to flac.
  • Files saved to a CF card
  • Battery: Li-Ion 3.6 V 7200mAh
  • Battery powers picaxe (4.5V), Gumstix (4.5V), and preamp (9V), voltage controlled using switching regulators
  • Total recorded: 400 files ~(6.6 hrs)