  The quasi normal modes (QNMs) associated with gravitational-wave signals from
binary black hole (BBH) mergers can provide deep insight into the remnant's
properties. Once design sensitivity is achieved, present ground-based
gravitational wave interferometers could detect potentially hundreds of BBH
signals in the coming years. For most, the ringdown phase will have a very weak
signal-to-noise ratio (SNR). Signal summation techniques allow information
extraction from the weak SNR ringdowns.
  We propose a method to constructively sum the (2,2) QNM from different BBH
signals by synchronizing and rescaling them. The parameter space adopted to
test the method is presently limited to mass ratio $q\leq3$, initially
non-spinning black holes with face-on orientation. Moreover, since the
synchronisation procedure fails for the weakest signals, we select all
ringdowns with SNR above 2.6. Under these conditions, we show that for
different BBH populations, 40 to 70% of all the potential detections could be
used for the summation while still ensuring a summed SNR of $\sim$80% of the
maximal achievable SNR (i.e. for ideally synchronized signals).
