Say I have a signal which is guaranteed to have a frequency between 110-120 Hz but is corrupted by interference signals that're very close to this frequency range. For example, let the interference signal have a frequency of 150 Hz and an amplitude of 10% if the fundamental.
What kind of filter or filtering technique would be suitable for estimating the frequency of the fundamental while ensuring that the group delay is low? I'm typically looking at a delay between 1-2 cycles of the fundamental frequency. I've experimented with Windowed sinc FIR filters having a cutoff frequency of 125 Hz & a stop band edge of 130 Hz but such a narrow pass band results in a high amount of group delay which'd be unacceptable for this application. The sample rate is pretty high at 25kHz.