# rough_cal_3d

Estimate scale factors and offsets for measurements from a triaxial field sensor.

#### Matlab & Octave

[X,G] = rough_cal_3d(X,fstr)

#### R

list <- rough_cal_3d(X, fstr)

Estimate scale factors and offsets for measurements from a triaxial field sensor. This function estimates the scale factor needed to make the magnitude of X close to the expected field strength. It then calls fix_offset_3d to correct any offset errors in X. This function does not try to optimize the results. See spherical_cal for a more powerful data-driven calibration method.

Input var Description Units
X is a sensor structure/list or matrix containing measurements from a triaxial field sensor such as an accelerometer or magnetometer. X can be in any units and frame.N/A
fstr is the expected field strength at the measurement location in the same units as X.nT
Output var Description Units
X is a sensor structure/list or matrix containing the adjusted triaxial sensor measurements. It is the same size and has the same sampling rate and units as the input data. If the input is a sensor structure/list, the output will be also.N/A
G is a calibration structure/list containing one field: G.polyG$poly. The first column of G.polyG$poly is the three scale factors applied to the columns of X. The second column of G.polyG$poly is the offset added to each column of X after scaling.N/A 1. This function requires a lot of data as it is looking for extreme values in each axis. A minimum data size of 1000 samples should be used. This function is only usable for field sensors. It will not work for gyroscope data. ### Matlab & Octave BW <- load_nc('testset1.nc') rcal <- rough_cal_3d(BW.M.data, fstr = 38.2) %fstr matches records for field strength in El Hierro when the tag was used plott(rcal.X, BW.sampling_rate) ### R BW <- beaked_whale rcal <- rough_cal_3d(BW$M$data, fstr = 38.2) #fstr matches records for field strength in El Hierro when the tag was used cal <- list(rcal = rcal$X)
plott(cal, BW\$sampling_rate)