MA2700A InterferenceHunter Help : MA2700A Overview : Connections : Compass Calibration
 
Compass Calibration
Anritsu recommends calibrating the MA2700A electronic compass before the first use and afterwards if the Anritsu instrument connected to the MA2700A is displaying unexpected signal direction readings. Use your Anritsu instrument measurement guide to open the External Compass Calibration menu and follow the onscreen instructions as shown in (Figure: Compass Calibration).
Compass Calibration
Note 
Electrical or magnetic fields can interfere with compass readings. When calibrating the compass be careful to stay well clear of electronics, high voltage power lines, magnetic devices, and masses of steel or iron.
These same precautions should be taken when mapping interference.