Ch 1. Introduction, Early History, and Assuring PNT (PTA)

Bradford W. Parkinson, Y. Jade Morton, Frank van Diggelen, James Spilker Jr.

This introduction chapter provides an overview of the topics covered in this two-volume set of books. It offers a historical perspective GPS and related position, navigation and timing (PNT) technology developments that led up to the proliferation of international GNSS in the past two decades. The chapter highlights some advanced applications that rely on GPS/GNSS. It also emphasizes the need for and proposes actions to protect, toughen, and augment (PTA) GPS for ensuring PNT availability and increasing robustness and accuracy.

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Figure 1.22 Cumulative launches of GNSS satellites (including SBAS) since 1978.