DCx16 waveforms. Pulse width voltage control.
The base frequency is 400 Hertz.
This is "Full Power." The width of the on-cycle is maximized but not actually 100% on. The 400 Hz frequency can actually be picked up by things such as relays.
This is Half-Power. The waveform is about evenly divided between ON and OFF.

The load sees a 50% duty cycle. Since it is 400Hz, you can't see any flicker.
As you may have noticed, there is a lot of noise in the waveform. It is there even when the DCx16 is "OFF."

Playing with time and voltage settings, I found the noise to be 4.5 Mhz and about 0.5 volts

I don't know if it can or should be filtered. My power supply was a 12vdc car battery so it isn't from the input power.