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by graycat 4174 days ago
Sounds like what used to be called inertial navigation and was used on the US SSBN (intercontinental ballistic missile firing submarines) before the Navy's version of the later USAF's GPS.

Inertial navigation was good enough to be quite useful before the Navy's version of GPS.

The Navy's version of GPS was done, at least started, at the Johns Hopkins University Applied Physics Laboratory (JHU/APL). They had a receiver on the roof, and it routinely navigated itself to within a foot.

I heard about that project because for a while I was doing applied math (the fast Fourier transform, power spectral estimation) and writing software in the JHU/APL group that did the orbit determination calculations for the satellites.

That project was a good example of how to do the technical side of a very ambitious project:

(1) Problem. The US Navy very much needed a means of navigation for the SSBNs.

(2) One or a few physics guys at the JHU/APL had an idea, of course, in terms of Doppler shifts from several satellites, etc., on the back of an envelope.

(3) Not much later, the project was approved.

Biggie Huge Project Point: Not long after the back of the envelope solution, the whole project was low risk and high payoff with, really, only routine, low risk work remaining.

Lesson 1: The problem sponsors were able to evaluate the project just on paper.

Lesson 2: After a good evaluation just on paper, the rest of the project was low risk and high payoff.

Lesson 3: The Navy did not say: You do the work, put up the satellites, show that it all works, and we will buy receivers for each of the dozen or so SSBNs.

For Silicon Valley: Want to do great projects, low risk, high ROI? Part of what you need to be able to do is to evaluate projects just on paper.

Of course, what evaluates well just on paper is mostly just the technical part. But start with a biggie problem so that clearly, obviously, no evaluation, no customer feedback needed, the first good or a much better solution is a must-have and not just a nice-to-have and where, due to the size of the problem (e.g., number of happy people times earnings per person), for financial success all that is left is that first good or much better solution and that is just technical and can be evaluated just on paper.

This way of doing projects is much of why the US has GPS, why the US Navy has it's version of GPS, why in WWII Patton at the Battle of the Bulge praised the US proximity fuse (a little radar set inside an artillery shell that told the shell when to explode -- great for exploding near an airplane or over the heads of troops) from the JHU/APL, the SR-71, the F-117 (Saddam, sorry you spent all that money on air defense -- all of it never put even on scratch on even one F-117).

Ah, Silicon Valley will never do that, not now!

1 comments

A lot of planes use that as well