`On Mon, 1 Aug 2005, Paulo Marques wrote:> Jan Engelhardt wrote:>>> So in order to calibrate it you need a readily available source of>>> constant acceleration, preferably with a known value.>>>>>> Hint: -9.8 m/sec^2.>>>> Drop it out of the window? :)>> No, no. Constant gravity (like having the laptop sitting on the desk)> "feels like" constant acceleration.>> Dropping it out of the window should measure 0 m/sec^2, because the> accelerometer is not working on an inertial referential (I hope this is> the correct term in english...). For the accelerometer, this is just> like the feeling of free falling inside an elevator: no gravity :)>> --> Paulo Marques - www.grupopie.comYou need a centrifuge or something that works like one. You canmake one and you can calibrate it using simple techniques. Forinstance, you can swing the mass (laptop) over your head, roundand round with your arm. If the rate is such that the mass "just"falls over the top, the 'G's at that point are zero. At thebottom of the swing, the 'G's will be maximum. If you used afish-scale (spring-scale) to swing the whole thing, you couldmeasure its static weight, then observe the apparent weighteverywhere along the swing arc. If you don't have to go through0 Gs, you can just swing the whole thing around horizontallyand observe the fish-scale. The 'G' load is exactly the indicatedweight / static weight.As a relative measure, a 5.5 lb weight, swung through a 5ftdiameter, (2.5 ft radius) arc at such a speed that it "just"falls through the top, exerts about 4 Gs (22 lb) at the bottom.Don't accidentally hit something. Impact Gs may make yourexperiment expensive.Cheers,Dick JohnsonPenguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).Warning : 98.36% of all statistics are fiction..I apologize for the following. I tried to kill it with the above dot :****************************************************************The information transmitted in this message is confidential and may be privileged.  Any review, retransmission, dissemination, or other use of this information by persons or entities other than the intended recipient is prohibited.  If you are not the intended recipient, please notify Analogic Corporation immediately - by replying to this message or by sending an email to DeliveryErrors@analogic.com - and destroy all copies of this information, including any attachments, without reading or disclosing them.Thank you.-To unsubscribe from this list: send the line "unsubscribe linux-kernel" inthe body of a message to majordomo@vger.kernel.orgMore majordomo info at  http://vger.kernel.org/majordomo-info.htmlPlease read the FAQ at  http://www.tux.org/lkml/`