In checking out the performance of the PicoScope, I found that it did not seem to work properly when then input sensitivity was set to anything more sensitive than 10V full-scale. I'm not sure why this is. It may be that this particular unit is defective, or maybe I am setting it up incorrectly. I was using a signal generator to make a sine wave at 20 KHz. When I set the input range on BOTH the scope display and the spectrum display to 10V full-scale, I got the correct spectrum. However, when I set the input sensitivity to anything less than 10V for either the scope trace or the spectrum display, or both, the display becomes incorrect. When this happens, the display shows warning icons from the PicoScope software, indicating overflow or clipping. However, I get these warnings regardless of the input signal level. The result of this is that the lowest signal level that can be seen on the spectrum display is about -55 dB.
Any help would be greatly appreciated!