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For instance , the earth 's rotation caused the ground receiver to move toward or away from the satellite 's orbit , creating a non-symmetric Doppler shift for approach and recession , allowing the receiver to determine whether it was east or west of the satellite 's north-south ground track .
 person: Doppler
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Doppler 
Answer:
 person: Doppler