Edge fluctuation data from both COMPASS-D and calculations with the large-eddy simulation code CUTIE have been analysed with a number of techniques, revealing coherent structures which exhibit high-frequency, standing-wave oscillations; some of those observed during edge localized modes (ELMs) have an `inverse-chirp' character and these are related to a disturbance of the plasma boundary in the lower-inboard quadrant of the poloidal plane. A `precursor' mode, seen in Ohmic discharges at about 220 kHz just before large ELMs, appears to be outward ballooning in character. Although the CUTIE calculations do not yet include ELM simulations, the results seem to correspond qualitatively with those seen between ELMs or during ELM-free periods on COMPASS-D.