Top panel: the radio emission of AR11227 in NRH 173.2 MHz and 228.0 MHz band and the RHESSI hard X-ray count rate in 12−25 KeV. The start time of the flare, Train-1, Train-2 and Train-3 are labeled at the time axis. Middle panel: the time-distance plot for L3. The samples used to measure the phase speed are enclosed in blue rectangles, the centers are labeled in red cross. The measured results are over-plotted within each rectangle as dashed curves. Bottom panel: the amplitude variation at a fixed height of about 150 Mm (marked in red line in the middle panel). The dotted lines mark approximately the wave cycles of three wave trains in varied color.