Self adjusting comparator tricks, anybody know any?

Currently I have a circuit that amplifies the signal from an inductive
loop pickup, band pass filters it using more op-amp stages, feeds it
thru one last op-amp stage to raise the slew rate of the signal, and
then finally passes it to a comparator that has its inverting input
biased to approx 2V. The output of the final op-amp is biased at 1/2Vcc
(2.5V) and fed to the comparators non-inverting input. This means the
comparator's output idles high and pulls low when the detected signal
drives the op-amp output below 2V. This is all well and good, but I
need to measure the time between detected impulses with high resolution
(1uS) using the capture/compare module in a PIC. This is easy enough,
but the problem is that the impulse being detected flips polarity each
time. This causes a phase error on the detection because the comparator
won't be triggered until the op-amp drives low again 1/2 cycle later.
This creates an unacceptable amount of jitter in the measurements. I
can live with the phase error caused by having to wait for the op-amp
output to drive low enough to trip the comparator as long as it is
fairly consistent since each impulse is quite consistent. The answer
seems to be to include another comparator wired in parallel, that has
it's non-inverting input biased at 3V and the op-amp output fed to the
inverting input, so that it pulls low when the op-amp's output rises
above 3V. I don't mind doing this, but it seems a bit messy in that I
will have to really fuss with the comparator's biasing voltages to get
it balanced well.

Now my question: Is there an easier way that won't involve fussy
adjustments? I like "self-working" tricks. ;-) The output from the
coil is very weak (millivolts) so diode rectification at that point
doesn't seem very likely.

.

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