I could calculate the timings as I have a .WAV file as result of sniffing what the sensor is transmiting.
The sample rate of the file is 48000Hz; I could count the sample points for every pulse and divide by 48000 in order to get the timing in microseconds.
For transmitting the same signal it would be then very easy using the delay() function. It's just I only need to receive and, in case the sensor detects a leak, Arduino should be able to execute a defined action (email, SMS ... etc.)
The captured file is here: http://www.ciproconsulting.it/pdf/Soundcard_TEST.wav
(used Audacity to record it)