Ok, say I have a sine wave block that has a frequency of 60Hz. What can I do to get that frequency as a number so I can use it as an input to another block? I've tried various things such as a "sign" block that counts when it switches from positive to negative and then a counter that resets after a second. That doesn't work. It counts up and resets, but it doesn't just tell me what the frequency of the signal is. I want something that will just say "hey, the frequency of the input signal is this." so I can feed it into another block. Essentially I am trying to get a frequency I can feed into a PID so I can control a variable frequency to keep it at a steady 60 Hz. I am actually trying to control the frequency of a Double fed induction generator that doesn't have a steady output voltage frequency. We can control the rotor frequency as a means of controlling the stator output frequency, but I am trying to do this automatically with a PID controller. I'm feeding the stator voltage into a controller that can run simulink models, but I can't get it to just say what the stator frequency is. I can't find anything is simulink that will just give me a block that has the frequency of the input signal that I can feed into something else. Any suggestions?