This is a non-contact flow meter for open water channels mounted above the water surface. It uses a radar velocity sensor and an ultrasonic sensor for water level measurement. The two measurements and the dimensions of the cross section profile are used to calculate the discharge from the continuity equation (velocity-area method). The modular transmitter incorporates a flow computer with all required algorithms and software to ensure accuracy and repeatability of flow measurements. Parameterization of the measurement site, data logging, visualisation and data transfer is possible by using the browser based control and management user interface, which can be run in any standard web browser via PC, notebook, tablet or smart phone, regardless of location, time and operating system. The transmitter can be mounted in a distance up to 100 m from the measuring site with the velocity and level sensors.