ETS is the process which allows the timebase to be set to display a waveform which would ordinarily require a sampling rate in excess of the maximum sampling rate for that instrument. This process can only work for repetitive signals (i.e. signals which repeat the same each cycle) since the way this actually works is by taking samples at different points in the cycle over a number of acquisitions and thereby building up a picture of the signal. In all Gould Digital Storage Oscilloscopes the timebase ranges which use the ETS process are clearly labeled as such.