Figure 3. Spectrograms of quasi-periodic hiss at 1230 UT at a northern station (a), at a southern station (b), and at 1232 UT at the northern station (c). The exit points of hiss from the ionosphere relative to the zenith of corresponding stations are shown to the right of the spectrograms. The exit points of the chorus are shown in the panel (d) in the range of 1.5-3.0 kHz.