I used Cool Edit 2000 to analyze the following slices of the audio waveforms:
- First 30 msec of the first character sent on semi break-in
- Third 30 msec of the first character sent on semi break-in. This allowed some time for the pitch to stabilize.
- First 30 msec of the initial dah sent in full break-in
- Third 30 msec of the initial dah sent in full break-in
The annotated screen shots are shown below. Click on any one for an expanded view. All have background noise showing in the upper part of the spectrum. The area of interest is the tone peak around 690 Hz.