Doppler¶

Doppler shift module.

acoustics.doppler.frequency_shift(frequency, velocity_source, velocity_receiver, soundspeed=343.0)[source]¶

Frequency shift due to Doppler effect.

Parameters:	frequency – Emitted frequency \(f\). velocity_source – Velocity of source \(v_s\). Positive if the source is moving away from the receiver (and negative in the other direction). velocity_receiver – Velocity of receiver \(v_r\). Positive if the receiver is moving towards the source (and negative in the other direction); soundspeed – Speed of sound \(c\).

\[f = \frac{c + v_r}{c + v_s} f_0\]

acoustics.doppler.velocity_from_doppler_shift(f1, f2, c=343.0)[source]¶

Calculate velocity based on measured frequency shifts due to Doppler shift.

Parameters:	c – Speed of sound \(c\). f1 – Lower frequency \(f_1\). f2 – Upper frequency \(f_2\).

\[v = c \cdot \left( \frac{f_2 - f_1}{f_2 + f_1} \right)\]

The assumption is made that the velocity is constant between the observation times.