Radio Tidegauge Receiver RGC705B-81, by Van Essen of Delft (The Netherlands), with a tide measuring unit and transmitter (3 parts). The radio tide measuring system type RGC705B measures the tide and transmits the measured value to the user by radio. The data received is displayed in digits and is suitable to be recorded printed or used for further handling. Tide measuring is delivered with a float, by which the real water level is measured, or with a pressure transducer. The waves are filtered out with wave restriction When applying a pressure transducer the signal is corrected for the specific gravity of the water and for the barometric pressure.