An ESP32 and a 24-bit ADC were used to capture the echo signal ... want to start seeing with sound, [Dzl]’s write-up has all the details you’ll need. If real radar is still your thing ...

As the train approaches, the sound waves that make up the whistle ... as "RF" on the color legend on the left side), the radar detected an echo but was unable to determine the wind velocity ...

Ultrasound travels at the speed of sound which is 330 m/s in air ... is transmitted and the time it takes for the reflection (the echo) to return is measured. The distance is calculated using ...