The Starlink satellite processions are generally observable with the naked eye or in most cases with binoculars at certain times of the night. However, they can also be observed as they pass in the daytime or if they are in the Earth’s shadow. In this case it is necessary to use reception of radio signals originating from a distant transmitter and reflected to the ground by the satellites themselves. Each radio station can record the transit of the satellites in a narrow window, where the transmitter-object-receiver geometry is favourable.  For example, in the case of the radio station located in the Planetarium of Venice Lido, which constantly receives the radio impulses sent by the Graves radar located in the centre of France, the reflection geometry of the signals became possible on 26 March 2020 from about 10h07m to 10h12m UTC.

The image shows the spectrogram in false colors of a short fraction of the event as a function of time and radio frequency, as generated by the acquisition software. The radio echoes were recorded at Venice Lido in sequence and an audio signal with a frequency more or less shifted according to the Doppler effect was generated by means of a demodulator.
A clear sound example of this can be heard by clicking the link in [1].

taken from