The purpose of this International Standard is to establish a flow Doppler test object for the acceptance testing, quality assurance testing and clinical calibration of Doppler systems, working at a frequency between 2 MHz and 10 MHz. As the response of Doppler systems depends on the signal level and on the spectral contents of the signal, it is desirable to test some aspects of a Doppler system with a test object that mimics the in vivo situation. This flow test object is not intended as a phantom mimicking clinical conditions.#,,#