A new system for measuring the betatron tune of the Fermilab Tevatron has been designed and tested. An unconventional phase‐locked loop using analog adaptive filters is used to lock to the betatron oscillation harmonic. The resulting tracking filters have narrow measurement bandwidth, and high quality factor, while maintaining a wide tracking range. Interfering signals can also be tracked and filtered out. The higher signal to noise ratio makes a significant improvement in the tune measurement accuracy. Shown are measurements and comparisons to the existing conventional phase‐locked loop systems.