As work on a USB ADC continues, somewhere along the lines the problem of
calibration came up both with regards to the sound card, and the
in-development peripheral.
It was quickly suggested that a crystal oscillator based circuit be used to
generate square waves to help calibrate the time scale of
Ceramic resonators are less expensive than crystals. Their stability
and accuracy is not as good as crystals, but is much better than RC
oscillators.
The waveform that comes from most oscillators is nominally a square
wave, but when the frequency gets into the tens of megahertz range, it
