Gyro Questions

[eugenebrooks]

Originally Posted by Rickertsen2

Could you elaborate on this a little? Exactly how does the nyqyist theorum, bandwith, sampling rate etc relate to this application? How do you calculate the needed bandwidth for something like this. I don't know much about such things but i would like to learn.

The simplest way to think about this particular situation is from the point of view that you are sampling the signal at discrete points in order to integrate the area under the curve as a function of time. It is most usefully done with the trapezoidal rule, but in any event it boils down to adding up the sampled points in some fashion.

Suppose now, that the signal is a sine wave at the maximum frequency the bandwidth of the gyro will support, and you sample at this frequency with the computer. The computer will periodically pick off the same point in the sine wave, and get whatever constant value your luck will deliver. It might be zero, but it might also be the maximum or minimum value, and the integral you would get would reflect this problem. You have a sine wave with an average of zero, but you are getting a bias in the time integral as if you are integrating a constant.

If you sample at twice the maximum frequency, you will get alternating negative and positive values, and no bias for the integral. If you sample at an even higher rate you will start correctly integrating the sine wave with precision. To obtain this desired result, you either increase the sampling rate used, or decrease the bandwidth of the gyro by adding a suitable capacitor.

Taking it a little further, have a look at: http://www.siggraph.org/education/ma...ing/alias3.htm