carrier demodulation an obvious application is fm stereo broadcasting for class 2 input signals the pll is typically used as a frequency demodulator since the pts provides some additional filtering it could be used to improve the quality of the fm carrier prior to subsequent demodulation because of the noise behavior of frequency demodulators a small improvement in signal to noise ratio snr prior to demodulation can result in significant improvement in snr of the recovered message i e the demodulator output the pts application here may also include coherent cancellation of the input fm carrier for class 3 input signals the pll portion of the pts will lock onto one typically the dominant sinusoid and 34 track 34 that one while ignoring the rest the ptc output is then the inverse of the sinusoid that has captured the pll a summing network provides cancellation of this sinusoid as shown in fig3 there v 11 t is v 0 t less one sinusoidal signal thus each cascaded circuit of fig3 will remove one tone for class 3 input signals the pts may also be used for coherent clock recovery coherent reference demodulation coherent signal synthesis and coherent cancellation for example one pts may be used to cancel a dominant interfering signal while a second pts is series may be used to recover a weaker pilot signal with phase coherence which can be used as a clock or as a coherent reference if one of the components of a class 3 input signal is modulated in amplitude it is still possible to provide cancellation by removing the am from the input signal with an envelope detector and remodulating the pts output signal prior to summing the summer then.