Compass calibration

Compass calibration requred before measurement if using a GPS. Calibration and evaluation less than 2 degrees according to RDI guidance. Better yet, should be less than 1 degree (evaluation) from USGS guidance.

We now use the Homan method to calibrate the streampro compass. It works best if you turn the instrument until you get a green bar. Then hold for 5 seconds or so. Then slowly turn the instrument until you get the next green bar. Then stop and hold for 5 seconds again. Continue on with this until you are finished in a complete circle. Then you will have to repeat it again for the evaluation and it will give you your score at the end. You should get less than 2 degrees error. Here is two people doing it, one person tends to work better (with a second on the computer): http://werc.engr.uaf.edu/~bob/discharge/2011_Itkillik_ADCP_Setups/large-1.html