I'm compiling all this info I've written previously into one cohesive post to answer any questions about what COPS and Sensi are and how they work.
COPS and Sensi were anti-chop systems developed by WDP and used in three of their angel models. Both systems make use of identical hardware, and the only difference is in programming. COPS was the first of the two to be released, and was used only on the IR3 model. Sensi was the second incarnation, and was used on the original 03/04 Speed and the A4.
Sensi is an effective system, but not as pro-active as break beam eyes. To put it another way, it will slow you down more than eyes would, but because of that, it does prevent chops. The system uses a rod that sticks up into the breach. The rod rests on a pad below the breach in the grip frame. When a ball falls onto the rod, it causes a vibration, which vibrates the pad. The pad stimulates a quartz crystal, which, through the piezoelectric effect, generates an electrical signal. The signal is read by the board to determine if a ball has fully loaded onto the breach rod or not. If a ball hasn't fully loaded, then a timed delay takes place. The Sensi mode you are using (there are 4) determines the length of the delay time, and what happens after the delay time. Either the delay will expire, and then the next trigger signal will only fire the ball if one has been detected, or the delay will expire and the next trigger pull after the delay will fire regardless of whether a paintball has been detected or not. The latter mode results in a shorter delay time, but also runs a higher risk of chopping. That's Sensi in a nutshell. Sensi got a bad reputation that was mostly handed down to it from the COPS system. The COPS system required a bit of "tweaking" depending on your loader and other settings. If it wasn't properly calibrated, it didn't work worth a damn. Sensi is self-calibrating, but many people were soured on the whole idea from the get-go, and many people complain about performance. In my experience with an 03 Speed and an A4, it has been effective if you pick the right Sensi mode for your hopper (the 2 longer-delay modes work better with gravity-fed hoppers, the short-delay modes work better with force-fed or high-speed hoppers).
COPS operated on the exact same hardware, but did not self-calibrate. Here's a little info on setting up COPS/COPS II (the second version of COPS software that came on IR3 board from Mem4 and up):
Ideally, COPS should only work when a ball falls onto the sensor rod. COPS operates identically to Sensi: a ball falls onto the breach rod, it vibrates the COPS pad in the gripframe, which vibrates a quartz crystal, which, through the piezoelectric effect, produces an electrical signal that the board reads as "ball present". Vibrations from shooting the gun, or diving, or other such things can accidentally cause a "ball present" signal if your sensitivity is set too high. The manual has very good instructions for setup (www.wdp.tv/manuals
). Basically, you need to rapidly dry fire the marker with the default Sens setting of 12, and adjust the Sens setting until your marker "throttles down" to the Bas number. For the sake of testing, put the Bas number very low (like 1) so that you can easily tell when the marker has "throttled down". When you get it to where the marker "throttles down" when dry firing, try it with paintballs. Ideally, the marker will fire as fast as you pull the trigger when a ball is detected, but "throttle down" if a ball isn't detected. If it doesn't throttle down with paint, then adjust the Sens level one number at a time until it works. When you're all finished, set the Bas setting to the appropriate speed for your loader. The Bas is the ROF that the gun throttles to if a ball isn't detected. You don't want to set it too high, because then you're more likely to chop because there will be a much shorter delay in the shot cycle when a ball isn't present. You want the shot cycle to delay enough that a ball is able to load. Originally, COPS only had Bas settings of 1-3, but people with faster loaders whined that it slowed the shot cycle down too much, so COPS II (new software released with the Mem4 board) has more adjustability. It's critical that you don't set the Bas too high. Many people over-estimate the capabilities of their loader, so they set the number way higher than it should be and then get upset when they chop.
This setup process is the reason why COPS got a bad rap. Most people either didn't take the time to set it up properly, or they set it up incorrectly so they still chopped. Properly setup, COPS will work. Unfortunately, people have the same attitude about Sensi, despite the fact that it is self-calibrating and doesn't require the same setup process. That's the primary reason why the A4 didn't sell very well until WDP equipped the Fly model with eyes.