Digital Coriolis mass flowmeter having random frequency driving signals

A flowmeter comprises a vibratable flowtube, a sensor connected to the flowtube for sensing the motion of the flowtube and a driver connected to the flowtube to impart energy to the flowtube. A random frequency generator generates random frequency signals 1708. A control and measurement system supplies the random frequency signals to the driver during a first mode of operation of the flowmeter. The random frequency signals may be filtered 1710 to remove unwanted frequency components. The control and measurement system is able to transition the flowmeter into a second mode of operation, characterised by a second drive signal. The fluid flow may be two or three phase (e.g. water, oil and gas) and the flowmeter may measure the mass flowrate or density of the fluid. A temperature or pressure sensor may be provided.