Posted by: Team - Bowhead whale | June 8, 2011

Bearing experiment

The 24/7 hydrophone station at Qaqqaliaq have now had its second month birthday and is still running. A very big Thank you goes to electronic wizard and opera lover Niels Christiansen Aarhus university-electronically workshop.  Niels patiently  helped and instructed and finally produced the first set of hydrophones that later were lost in the winter 2007-08 .  He  also soldered – printed diagrams-   and so forth  to repeat the whole procedure once more for the set of hydrophones we are now using. We now have a set of continuos  recordings for more than 1500 hours except for  a few fall outs when cables have been cut by ice. Specially the small red ground cable is vulnerable.

Outi and the recording equipment. Photo: M. Christoffersen

To verify the recordings we did set out on the evening of  the 5 june to make bearing experiment and a  intensity level  calibration . Maja S was placed in a fixed and known position and the crew were told to make  underwater sounds from the boat.  A commercial calibrated hydrophone was then placed beside one of the  fixed hydrophones and afterwards sensitivity can be compared. During the session  Maja S was moved to different positions to verify the resolution on the bearings from the fixed array.

Maja S disappearing behind an iceberg in an attempt to measure the shadowing effext of an iceberg. Photo: M. Christoffersen

Maja S behind an iceberg.. Photo: M. Christoffersen

And Maja S in sight again. Photo: M. Christoffersen

The whole evening ice was troubling us as small icebergs obstructed the line towards the ship or  banged at the bottom to make a infernal noise. When we were ready to leave  high tide had  left us onshore unable to reach the dinghy and we had to wade in seawater to the belly button to get on board. Murphys law was working! But the sun was shining all night and the crew were incredible patient. Well onboard and treated with hot tea and honey  mood was again  high as we entered the harbour at  01 in the night.