I think I understand that the minimum of the Allen variance is the "in-run bias stability", measured with the benign conditions of ideal averaging, stable temperature, and no inertial motion. For the ADIS-16490, for example, that's 1.8 deg/hr, given as a typical spec and the average on the Allen chart.

**First question:** does that mean that 67% (one sigma) of ADIS-16490 devices will show a heading deviation (integrated deg/s output) of up to 1.8 deg after an hour, if they're sitting still? This would have to include bias effect too, then, not just noise.

**Next question:** how do I determine the real-world error over temperature which I might expect? It seems like sensitivity, nonlinearity, and bias effects like repeatability and tempco errors would have to be added to the in-run bias stability figure.

**And finally:** what should I do to get the very best performance? Operate in a constant-temp oven? Do system calibration for temp? For sensitivity (i.e. over the full range of input rotation speeds)? What are the repeatable error factors I can calibrate out?

Thanks very much for any help,

Gerrit

First question:does that mean that 67% (one sigma) of ADIS-16490 devices will show a heading deviation (integrated deg/s output) of up to 1.8 deg after an hour, if they're sitting still? This would have to include bias effect too, then, not just noise.ANSWER:I am not familiar with the term, "bias effect." In-run bias stability represents the accuracy in which you can observe the bias of that gyroscope, under static conditions and with ideal integration time. For heading estimation, it represents the best possible performance. Mean + sigma means that 67% of the units will offer this level of performance, or better.