Define the signal first
Document useful input frequencies, amplitude and simultaneous channels. For baseband sampling, Nyquist is a starting point: real filters need a transition band.
Filter before conversion
Unwanted high-frequency content can fold into the useful band. A digital filter after the ADC cannot distinguish it from the original signal. Match the analog filter to the measurement bandwidth.
Converter checklist
- Input bandwidth and amplitude range
- Sampling rate and dynamic performance at the intended frequency
- Channel synchronization and transfer capacity
- Calibration and real-world noise tests
Bandpass undersampling requires its own spectrum and Nyquist-zone analysis.