drive a periodic waveform and sample repeatedly. Assuming you don't somehow sample the same point in the periodic waveform each time, you'll eventually get the complete waveform.
> Assuming you don't somehow sample the same point in the periodic waveform each time, you'll eventually get the complete waveform.
To add an example of a real technique: You can use a short laser pulse and change the time-of-flight (mirrored path on a stepper motor, for instance). This technique will get you to the terahertz region, which is pretty much state of the art for where electronic devices still have gain.
To add an example of a real technique: You can use a short laser pulse and change the time-of-flight (mirrored path on a stepper motor, for instance). This technique will get you to the terahertz region, which is pretty much state of the art for where electronic devices still have gain.
http://en.wikipedia.org/wiki/Terahertz_time-domain_spectrosc...