Bill Clinton eliminated Selective Availability distortion in the GPS signal. The US government thus chose to remove the intentional deterioration in GPS accuracy for public use (Selective Availability). The “military” precision of GPS became usable by the general public, free of charge. Six years earlier, I had written my thesis on an aerospace application of this system, and at the time I fully understood the significance of this decision, which is now clear: GPS is used daily by everyone. And also the importance of having this lever, which I compare to John Harrison’s invention of portable watches for maritime use to calculate longitude precisely (there’s a great book by Dava Sobel), which was long jealously guarded as a military secret by the Royal Navy… Today, GPS is supported by several other similar or complementary satellite systems: GLONASS (Russia), Galileo (Europe), Beidou (China), QZSS (Japan), IRNSS (India).
