摘要：Although satellite navigation signals and systems have been designed for more than 40 years, new signals and systems are still being developed. During that time, design concepts have been weighed, implemented or rejected, and improved. Some early concepts ¡ª postponed because of impracticality at the time ¡ª have been revisited and adopted. This article by a noted GNSS signal expert introduces a framework to provide perspectives on past and present signal structures, and offers some conjectures about the future development of satnav signals
