Determining Frequency On An A/d Channel

[AshPowers]

I have constructed a turbine rotor balancing rig and and acclimating myself to DAQFactory so please bear with me.

 

I have incorporated a small magnetic angle position sensor to the rig which has a sawtooth analog output signal. This is connected in to a differential analog input on a Labjack U12.  I am trying to figure out how to setup the program to determine the RPM of the rotor.

 

Here is a screenshot of what the signals look like: (blue is the position sensor).

 

 

Any help here is greatly appreciated! =)

 

-Ash