I am trying to understand RAIM. My teacher explained three RAIM methods, I will just quote all of them because I think that the jargon might not be consistent.

  1. Maximum separation / Position comparison method (PCM): Different combinations of satellites calculate the position of the receiver and these results are compared with statistical methods

  2. Pseudo-Range residual / Range comparison method (RCM): All satellites calculate one solution. The residuals of the pseudo ranges are then investigated with statistical methods.

  3. Parity space: The teacher said that the system of equations of the satellites is transformed orthogonally with constraint equations. And these constraint equations are used to detect statistical inconsistencies.

My question: Could someone explain me in normal words what the parity space method does? If there is a simple/short mathematical explanation that would be great. Did I explain the first and second method correctly?

  • $\begingroup$ Good question, well-posed. If you don't get an answer here and find out by researching elsewhere, I hope you'll post a self-answer - I'd be interested to learn about that parity space method. I've only ever implemented the first two methods you listed; I think you explained them adequately. $\endgroup$ – pericynthion Aug 5 '17 at 18:52
  • $\begingroup$ @MrYouMath You may find this interesting: Does GPS spoofing ever come from space? How are spoofings usually detected? $\endgroup$ – uhoh Apr 3 '19 at 1:04

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