question: What are the two satellite constellations ?
answer: a limited test system that has been operating since 2000 , and a full-scale global navigation system
turker_answer: The two satellite constellations are a limited test system that has been operating since 2000 , and a full-scale global navigation system .
rule-based: The two satellite constellations are a limited test system that has been operating since 2000 , and a full-scale global navigation system .