SA made GPS accurate to 10m.. With the "SA" feature disabled, you're down to 2m... And with Satelite enhancements, it's more like 20cm !
But that's irrelevant.. Because SA was intended to disable any enemy force from using GPS for accurate positioning - until they realized D-GPS (Differential GPS) made the whole point moot (you take a reference point - you send the signal to the receiver - And therefore - the receiver can deduce the SA introduced clock error - because now you have a ref point
However, the military still keep exclusive use of the 1Mhz band (with the 10Mhz being public) - for the only purpose of being able to make real time measurements on tropospheric distortions - so - what happens - is that the military can make 1m accurate reading WITHOUT sat aids.
Unfortunately, it is. The general thinking among some examiners is that the bigger companies mostly get patents defensively (i.e. to stop others from suing them with the threat of a big patent portfolio). They see it as harmless to let something like this out because a patent like this would likely be used against another company with enough money to shoot it down.
Yeah, HP shouldn't try patenting this...
In my time at the USPTO, I noticed that HP took the phrase "anything under the sun made by man" to the extreme and tried to patent everything under the sun made by man in every patent app filed. Each case was an absolute battle to get them to claim what they really invented. If the examiner wasn't willing to fight it out on the case, he or she could have just easily said "Screw it! They won't try to enforce it anyway..." and just allowed the case.
By MS helping to implement parts of Mono, they have, at a minimum, given up their rights to sue over those portions with which it helped. IANAL, but I have worked in the world of IP for a few years and from what I understand, MS has surrendered its rights to sue over those portions of Mono because of promissory estoppel. That is, since Mono was being implemented with help from MS, thereby giving the project its blessing to continue, MS has essentially given the developers of Mono a promise that it is OK for them to continue on.
What remains to be seen is whether or not MS would be allowed to sue for those portions of Mono that were implemented without help from MS. As usual, software development makes established IP law far more interesting to apply...
It has already been done.
Numeric stability is probably not all that important when you're guessing.