Comparison of observations by PSP and WIND when the minimum azimuth difference Δθ < 30° in the two cases of PSP near orbital perihelion and aphelion. Panel (a) shows the positions of Earth (or WIND) and PSP when PSP approaches the perihelion on 2019 April 6. The corresponding dynamic spectra observed by PSP and WIND at 07:30–12:00 UT on this day are shown in panels (c) and (e), respectively. In contrast, panels (b), (d), and (f) show the case of PSP near its aphelion on 2020 July 21, and the corresponding dynamic spectra observed by PSP and WIND at 01:00–08:30 UT, respectively.