inertial nav
Hello all,
Here is a question about inertial nav initial alignment: It is my understanding that the IRU, when it is initially aligned at rest on the ground actually finds true north thru a gyro-compassing technique (I understand the basic idea here, it is pretty neat). I can see how this works for the old style spinning gyro's. But apparently a similar thing happens for fiber-optic gyros and ring laser gyros (Sagnac effect, etc). Does anyone have better insight on the alignment technique, or a good engineering reference?
As an aside there was a recent Scientific American issue about Einstein and his legacy. He was apparently very involved in the early patent fight over the gyro-compassing technique. It was also mentioned that GPS position would not be more accurate than about 30 meters if relativisitic affects are not accounted for (not considering a differential GPS system).