- The group delay describes the delay between the analog signal being present at the input to when it is seen at the digital output. For a single tone sine wave, for instance, it is the time between the voltage peak of the sine wave existing at the analog input and the same peak appearing at the digital output.
- The settling time is the full averaging time of the digital filter. If there were a step at the analog input, it takes the full settling time of the filter until the data output from the ADC has no correlation with that previous step at the input.
- The data collected after spanning the group delay is not the most accurate or settled data, but it is able to give an early indication that a change in the input has happened. This is helpful for low latency applications (i.e. car crash testing and response).
- The data collected after spanning the settling time is more frequently used and it is for precision measurement. Below is an example of Sinc5 step response
- The group delay is approximately half of the settling time.