Context: The investigation of the transmitted signals started immediately after the launch of Compass -M1 on 14 April 2007. Soon after in June 2007, engineers at CNES reported the spectrum and structure of the signals. A month later, researchers from Stanford University reported the complete decoding of the “I” signals components. The knowledge of the codes allowed a group of engineers at Septentrio to build the COMPASS receiver and report tracking and multipath characteristics of the “I” signals on E2 and E5B.

Question: When did the investigation of the signals transmitted by Compass -M1 begin?
Answer: immediately after the launch of Compass -M1 on 14 April 2007

Question: What did engineers at CNES report in June 2007?
Answer: the spectrum and structure of the signals

Question: Who reported the complete decoding of the “I” signals components?
Answer: researchers from Stanford University

Question: Who built the COMPASS receiver?
Answer: a group of engineers at Septentrio

Question: What was the purpose of building the COMPASS receiver?
Answer: report tracking and multipath characteristics of the “I” signals on E2 and E5B

Question: In what month of 2008 was Compass-M1 launched?
Answer: Unanswerable

Question: In March of what year was Compass-M1 launched?
Answer: Unanswerable

Question: Yale University researchers decoded what?
Answer: Unanswerable

Question: Knowing the codes allowed Stanford researchers to build which receiver? 
Answer: Unanswerable

Question: Knowing the codes allowed Stanford researchers to build the NERF receiver and report what? 
Answer: Unanswerable