Originally Posted by
microe 
Mice have some characteristics that we have in general classified using the following terms:
Tracking Speed: Moving the mouse quickly is reported correctly by the mouse. Some mice when you move them too fast will lose tracking and either stop reporting entirely or spaz out and give you random reports or cap out at some count.
Move the mouse very quickly and look at the velocity. In general you should see a curve that is unbroken and maybe has some jitter at high speeds. If the velocity drops to zero or there is some garbage then the mouse lost tracking. The highest velocity along the curve that still looks okay is in general the max tracking speed. Some mice the top of the curve is a plateau, this is indicative of internal data path saturation in the mouse sensor or firmware which results in negative acceleration. Others have used Enotus in the past, but without the data curve plotted you can't see if Enotus is falsely reporting because of some garbage or jitter from the mouse.
Acceleration: Moving the mouse the same distance fast results in different total reported counts than when we move it slow. Can be positive (moves farther the faster the mouse moves) or negative (moves less the faster you move the mouse).
Move the mouse fast in one direction and then move the mouse slow back to exactly the original position. If you plot the X-Y you should see the mouse counts return exactly back to the origin. You can also do this test in game and there are some youtube videos of in-game tests.
Jitter: Moving the mouse in a relatively straight line results in an inconsistent (random staircase) movement.
Move the mouse slowly in a diagonal motion and view the data in the X-Y plot. You are looking for big stair-step or non-linearity along the path. Look around for old Razer Abyssus paint plots.
Angle Snapping/Prediction/Drift Control: This one has been called a few things but in general it is the mouse reporting straight line movement even when the user might have meant to draw a slight angle or curve.
You can sometimes see this during the fast swipes for max tracking rate. The "Y" reports from the mouse will go to zero and hold there (which is highly unlikely from swiping your mouse fast). The other way is to draw a circle and see if the mouse "forces" a straight line. People have done this in paint or you can do this with the X-Y plot and capturing a circle. One of the nice things with my tool is you can draw the shapes in paint and then plot the corresponding raw data with my tool, as long as it is one complete motion and you hold the button down the entire time.
Excessive Anti-Jitter: Moving the mouse slightly or very slowly from a standstill may result in a delay or no movement registration.
Move the mouse very slowly and see what the counts reports look like. This one is kind of hard to test.
Polling Rate Consistency: Move the mouse and see if the report rate from the mouse is consistent at the supposed setting (125, 500, 1000 Hz). Some mice have had a problem with 1000 Hz in the past.
Just move the mouse around and plot the interval. It should be a relatively straight line at the desired report rate. 1ms = 1000 Hz of course. There are other report rate measuring tools out there.
Interpolation: Scaling the counts from a mouse to one that is not native to the sensor. Magnified counts is a form of interpolating CPI up, while halving counts can be seen as a form of interpolating down. Doesn't have to be a power of two, can be any factor since it's just math. Mouse driver sensitivity slider is a form of interpolation that runs on the PC.
This one you can't really see with my tool alone. If I had an oscilloscope and captured the communications from the sensor to the mouse microprocessor and compared that to the counts from the microprocessor reported to the PC then I could see if the mouse microprocessor is interpolating the data.
Measuring CPI: 400 DPI/CPI isn't necessarily 400 CPI! Due to manufacturing tolerance and other factors the CPI that you set may not be exact. You can use my tool to measure the "real" CPI and compare that to the "desired" CPI setting. Some mice are way off, others are dead on. Ruler + counts doesn't lie, but of course take into account human error and maybe do some averaging. Moving the mouse quickly is reported correctly by the mouse. Some mice when you move them too fast will lose tracking and either stop reporting entirely or spaz out and give you random reports or cap out at some count.
Move the mouse very quickly and look at the velocity. In general you should see a curve that is unbroken and maybe has some jitter at high speeds. If the velocity drops to zero or there is some garbage then the mouse lost tracking. The highest velocity along the curve that still looks okay is in general the max tracking speed. Some mice the top of the curve is a plateau, this is indicative of internal data path saturation in the mouse sensor or firmware which results in negative acceleration. Others have used Enotus in the past, but without the data curve plotted you can't see if Enotus is falsely reporting because of some garbage or jitter from the mouse.
Smoothing/Frame-Induced Delay:This is a new one that has come up recently but unfortunately it is very difficult to measure, the following is my somewhat simplified understanding of the process. The mouse sensor acquires images of the surface called "frames". The frame rate of the sensor may or may not be constant. There are signal processing algorithms that takes these frames and translates them into counts. Depending on the signal processing algorithm there is an inherent latency from when the movement occurs to when the sensor has the counts available in the motion registers (frame delay). These counts are acquired from the sensor by an external microcontroller which accumulates these counts, optionally does some additional processing, finally sending a value to the PC on the next USB poll.
