question: What are the four bands of frequencies used by the COMPASS system called ?
answer: E1 , E2 , E5B , and E6
turker_answer: The four bands of frequencies used by the COMPASS system are called E1 , E2 , E5B , and E6 .
rule-based: The four bands of frequencies used by the COMPASS system are called E1 , E2 , E5B , and E6 .