The signal arriving from the probe is analog. It needs to be transform into a digital signal.
- The analog signal arrives at the digitizer
- Data points are taken along the analog signal to create a digital equivalent. In most digital instruments, the points are taken at a rate of 100 MHz which means one point every microsecond (10-6 second)
The rule of thumb for digital signal quality is a sampling rate 5 times faster than the frequency of the probe. Hence, a 100 MHz sampling rate is sufficient for probes up to 20 MHz.