[GreenKeys] Fw: BBC enquiry - telegraph machine

[Jim Haynes]

An undulator is an ink recorder.  Like a slow oscillograph, the inked line 
displays on a moving paper tape the polarity and amplitude of the signal 
coming out of an ocean cable.  In ocean cable work they used one polarity
for dot and the other for dash, thus gaining speed.  And they tended to
push the speed of signaling above the bandwidth of the cable, so that
the operator had to infer what was sent from the wiggles on the tape.

Ink recorders were also used in high-speed Morse work (up to 500 wpm
on radio circuits) but I don't think those were called undulators.  And
they used conventional Morse make-and-break keying so the dashes were
3 times as long as the dots.

jhhaynes at earthlink dot net