Once the carrier is stripped out, there are going to be two remaining frequencies 10kHz and 15kHz. One represents a binary high and the other the low. I need to monitor the time the signal is either high or low, and I am looking to have .000001s resolution (I may have missed a 0in there).
I am thinking about passing it through a low pass filter, then doing a 64 point FFT with an overlapping moving window. I will then have a threshold that I start a counter once a requency reaches a certain level.