If the starting point is that the error is random, your arguments all fade away. Averaging many measurements will result in a lower range of error with some probability. No measurement is contained in an error window with 100% probability.
Sylvia Else wrote in news:gc9co2Fmqn1U1 @mid.individual.net:
One exception might be when paralelling resistors. 1% resistors in paralell will generally be more accurate than the original spec. Maybe due to the way precision classed resistor sets get matched and culled. One can generally count on the members of the set to actually be more accurate than the spec they claim to be at least as good as.
Sylvia Else wrote in news: firstname.lastname@example.org:
The same reason that a mil-spec part had additional testing done on it. Cost. higher class chips cost more, but not always due to hard internal differences so much as exceptional performance compared to the rest of the lot.
Intel cpus still got sold when they exhibited too much heat ran at speced rate. Ran slower. Tag it with a different name, and sell it as a slower version. The 486's that had failed math cos still got sold. Intel die issues. Have to keep to a minimum the number of failed units on a single platter.
OK I did the sums. Based on the random walk of a laser ring gyro (0.0035 deg/sqrt-hour) and that of a MEMS accelerometer (2.25 deg/sqrt-hour) , you need about 400k MEMS accelerometers to approach the accuracy of a laser ring gyro.
It sounds like a lot of components to solder together but if done in a chip fab, it should be possible.
Is it possible to make a commercial accelerometer with no export restrictions by using such an array? Or will ITAR or the like be slapped on such a device once its accuracy is published in a brochure?
Refs:  Honeywell GG1320AN Digital Laser Gyro brochure  Error and Performance Analysis of MEMS-based Inertial Sensors with a Low-Cost GPS Receiver. Park, M & Gao, Y.  Sensors Vol 8
Incorrect. On the same superstructure there will be additional structural v ibrations whose amplitude and frequency are position-dependent. While these vibrations do not result in a net spatial or angular translation (you woul d hope so!) for the math to work the accelerometers have to be at the same location, the closer the better, sampling the same thing.
Within a chip yes.
The accuracy is good enough, especially if the gyros are only used in porti ons of the journey where other sensors (e.g. GPS) are unavailable, such as indoors or underground.
Perhaps you are saying this in a tongue in cheek way, but ITAR is one of th ose things where you are expected to know your device is restricted without anyone in the government telling you. Not only are you required to not se ll it to the wrong people, but you are supposed to know that the people you sell it to won't sell it to the wrong people.
A UK seismometer company did (does?) just this, 16 MEMS accelerometers per axis. I don't know what the improvement is, but I'm certain they'd lie about it knowing the customer couldn't check. [That's why I only stayed there a few months, shocking quality and shocking performance exaggeration.]