USN Captain Mark Mathews said: "The frequency, it was a repetitive signal every second, the pulse whip was about 10 milliseconds in length - that's appropriate for the signal."
I thought the Dukane Seacom ULB MH370 was outfitted with has a signal interval of 0.9 seconds. Teledyne/Benthos models have a 1 second interval.
rampstriker,
It's a 10 ms pulse of 37.5 kHz ultrasound, repeated every 0.9 seconds. That's a duty cycle of 10/900 or about 1.1%.