Bug Keys (5)

bugkey10

Now, we are sending six dots, the red trace showing the signal obtained at the dot contact, and the yellow trace out of a simple debounce circuit in an FPGA.

It is easy to include a counter in the device for measuring the length of marks and spaces.

bugkey9

By manually reading the numbers in the above figure, you can write a short script in R.

% R
> dat_v=c(1034, 883, 1028, 889, 1003, 923, 1053, 871, 1024, 901, 1048)
> barplot(dat_v, col=c("blue", "green"))

bugkey11

The blue bars correspond to the mark (=low) length, and the green ones to the space (=high). You will immediately notice that the mark to space ratio is not 1.0, and some more adjustment is required.

Bug Keys (4) dirty signals

dirty1

dirty2

If your bug key is not properly maintained mechanically, you will get very dirty signals, as is shown in the above figures, very easily.

You will notice something is wrong without observing the waveform, because the side tone, for example, sounds very annoying in such cases.

dirty3

After some cleaning of the dot contact, somewhat better signal is obtained, but the mark/space ratio is not correct, because during the process I touched some of the screws determining the gaps.

dirty4

The waveform looks acceptable now, but I still do not know how to do it in a reproducible manner.

http://www.vibroplex.com/techdocs/original_bug_adjustments.pdf