Below are the wavelet ridges of the sum of parallel linear chirps.
The frequency tracking gets worse as the frequencies increase. This is because the frequency resolution of the wavelet transform decreases when the frequency increases. Indeed, for these linear chirps, the relative frequency difference goes to 0 as t increases, and this creates "interferences" between the ridges. Similarly, interferences can be observed in the figure below, at t=900, between the linear chirp and the lower frequency Gabor chirp.
On the contrary, the increase of time resolution as the frequency increases makes it possible to track the instantaneous frequencies of the hyperbolic chirps:
Conclusion on Instantaneous Frequency Detection