I try explain to all how work my little instrument. Who know English better than me (my is very bad), please help me correct the text below.
Mouse with polling rate 500 Hz send movement data to OS each 2 ms (1/500 Hz = 0.002 s = 2 ms). What kind of data? It's counts.
If you move mouse with 400 CPI (C
nch) for 2 inch, than OS recive 800 counts (400 cpi x 2 inch). Just imagine that in first 2 ms mouse send to OS 200 counts, in second 2 ms - 400 counts, in third - 200 counts. Sum = 200+400+200 = 800 counts.So in first 2 ms mouse moved for: 200counts/400cpi=0.5 inch. In second 2 ms: 400counts/400cpi=1 inch. In third 2 ms: 200counts/400cpi=0.5 inch. So, speed in first 2 ms: 0.5inch/2ms= 0.5inch/0.002s = 250 inch/sec. Speed in second 2 ms: 1inch/2ms= 1inch/0.002s = 500 inch/sec. Speed in third 2 ms: 0.5inch/2ms= 0.5inch/0.002s = 250 inch/sec.
We can record data of mouse movent by loger into the file and convert that file to wav. When we open this file in sound editor we can see time on horizontal axis (with 2 ms step - OS recived data every 2 ms or mouse work with 500 Hz polling rate). On vertical axis we can see counts recived by OS (or sended by mouse). Now we can convert counts to speed in "mm/s". Method described above. Final formula is: 25,4/(CPI*T), where 25,4 = number of mm in 1 inch, CPI - mouse CPI, T - polling rate in seconds (for 2 ms it's 2/1000 = 0.002 seconds).
For mouse with 400 CPI and 500 Hz (2 ms) it's 25.4/(400*0.002)=31,75. So we should increase scale (amplify signal in audio editor) in 31.75 times (or 3175%) to get "mm/s" on vertical axis.
Now results of real expirements:
One of recorded movements for Logitech G3 mouse:
We can see that sensor fall to zero when mouse reach speed about 2000 mm/sec. You can think that is malfunction speed. But is not accuracy. We can see that sensor start catch surface in about 1600 mm/sec - it's more impotant for us. And after analyse other recorded movments we can shurely say that real malfunction speed on tested surface is about 1500-1600 mm/sec.
One of recorded movements for IMO 1.1a:
In this graph we can see that negaccel speed of IMO 1.1a is about 1500 mm/sec. And when speed reach peak (it's about 2000-2200 mm/sec) cursor speed don't fall to zero as G3. It just get a little lower than negaccel value. It's good.
So, I measure with this simple instruments perfomance of two mouse in specific surface and estimate negaccel speed for MS, and malunction speed for G3. In my opinion 1.1a work better than G3 on this surface.Edited by outerspace - 1/22/11 at 10:26am