NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Origins of civilian use of GPS
From: Peter Monta
Date: 2018 Jul 6, 08:58 -0700
From: Peter Monta
Date: 2018 Jul 6, 08:58 -0700
> Many recent articles and books claim that GPS was a military only system prior to the shooting down of KAL007. I discuss this in a recent article.
As you know, surveyors and geodesists were also very early with civilian use of the system, in particular with carrier-phase modes, codeless and semicodeless L2, and precise orbits. While this was not real-time navigation, it was still a significant civilian use, so there must have been some awareness at the time that such use was possible.
You mention Transit in your article: whether it was 2D or 3D depends on the use case. For a single pass, yes, height is roughly degenerate with longitude, so you need to fix the antenna height. But with multiple passes (which will take at least a few hours), a full 3D position is possible. If the Transit constellation had been larger, say a dozen or so satellites per plane, it would have been a near-real-time 3D system.
Cheers,
As you know, surveyors and geodesists were also very early with civilian use of the system, in particular with carrier-phase modes, codeless and semicodeless L2, and precise orbits. While this was not real-time navigation, it was still a significant civilian use, so there must have been some awareness at the time that such use was possible.
You mention Transit in your article: whether it was 2D or 3D depends on the use case. For a single pass, yes, height is roughly degenerate with longitude, so you need to fix the antenna height. But with multiple passes (which will take at least a few hours), a full 3D position is possible. If the Transit constellation had been larger, say a dozen or so satellites per plane, it would have been a near-real-time 3D system.
Cheers,
Peter
