vertical frequency: English: Vertical scan rate, also refresh rate, indicates the speed that the electron beam needs to build up a complete image, measured in Hertz (see Hertz). At a TV picture after PAL-Standard (see PAL) this is 50 Hz, with a NTSC-Picture (see NTSC) 60 Hz, a good one roar-Monitor has at least 80 Hz, below 50 Hz the vertical frequency is perceived by the eye as increasingly noticeable flickering.
