Hi Brooke, There is no proposed theoretical basis for the statement below, is there? It sounds like it was arrived at by just surveying existing technology. I've used QRS rate gyros which are around 1 deg/sec/hr drift, which is almost 10 times better than what is given in your table. (They cost $$$$) MEMS rate gyros have a trade-off between bandwidth and noise. Air (or any gas) inside the sensor causes noise by random motion of the molecules. However, it also provides damping (this is basically Johnson noise which all dampers have), thus broadening the bandwidth, which is desirable. Thus, the noise floor (and partly the drift) is somewhat determined by the necessary bandwidth. One could probably take two rate gyros (a low noise, low bandwidth one and a high noise, high-bandwidth one) and combine their outputs with a Kalman filter or somesuch and get the benefits of both. I also don't think that laser ring gyros are as small as they could possibly get (although I know little about them). Sean On Thu, Mar 6, 2008 at 1:17 PM, Brooke Clarke wrote: > Another interesting thing about gyros is that there long term drift rate is a > function of the volume of the sensor independent of the type of sensor. I > posted at table at: > http://www.prc68.com/I/Sensors.shtml#Gyroscopic > > -- > Have Fun, > > Brooke Clarke > http://www.prc68.com/P/Prod.html Products I make and sell > http://www.prc68.com/Alpha.shtml All my web pages listed based on html name > http://www.PRC68.com > http://www.precisionclock.com > http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Web Cam > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist