Compass-M1 transmits in 3 bands: E2, E5B, and E6. In each frequency band two coherent sub-signals have been detected with a phase shift of 90 degrees (in quadrature). These signal components are further referred to as "I" and "Q". The "I" components have shorter codes and are likely to be intended for the open service. The "Q" components have much longer codes, are more interference resistive, and are probably intended for the restricted service. IQ modulation has been the method in both wired and wireless digital modulation since morsetting carrier signal 100 years ago. COUNT 5
QSN1 What frequency bands does Compass-M1 transmit in? ANS1 E2, E5B, and E6 QSN2 What is the phase shift of the sub-signals detected in each frequency band used by  Compass-M1? ANS2 90 degrees (in quadrature) QSN3 What are the two sub-signals in each frequency band referred to as? ANS3 "I" and "Q" QSN4 What is the intended purpose of the "I" component? ANS4 likely to be intended for the open service QSN5 What is the intended purpose of the "Q" component? ANS5 probably intended for the restricted service