  We propose a novel, frequency-domain approach to the analysis of the
gravitational-wave ringdown signal of binary black holes and the identification
of quasinormal mode frequencies of the remnant. Our approach avoids the issues
of spectral leakage that would normally be expected (associated with the abrupt
start of the ringdown) by modeling the inspiral and merger parts of the signal
using a flexible sum of sine-Gaussian wavelets truncated at the onset of the
ringdown. Performing the analysis in the frequency domain allows us to use
standard (and by now well-established) Bayesian inference pipelines for
gravitational wave data as well as giving us the ability to readily search over
the sky position and the ringdown start time, although we find that it is
necessary to use an informative prior for the latter. We test our method by
using it to analyze several simulated signals with varying signal-to-noise
ratios injected into two- and three-detector networks. We find that our
frequency-domain approach is generally able to place tighter constraints on the
remnant black-hole mass and spin than a standard time-domain analysis.
