Spike chain A recordings from SAO and NRH. Upper panel: SAO dynamic spectrum for spike chain A (box in Fig. 2). The corresponding frequency of the NRH is marked on the right. Next panel: the NS 1D NRH images at 327 MHz. Last panel: we show NRH (blue) and SAO (red) normalized total flux time profiles at 327 MHz and at 150 ms resolution are presented; a second SAO high-resolution (10 ms) profile (red dotted) is included for comparison. Twelve spike-like structures, numbered (1–12), are marked by vertical dashed lines.