Method and level measuring device for determining the level of a medium by means of continuous wave radar measurement

摘要

A method (1) for determining the fill level of a medium (2) by means of CW radar measurement and a corresponding fill level measuring device (3) is described and illustrated, wherein a code sequence (7) is generated by a code sequence generator (6) and transmitted by a transmitter ( 8), a transmission signal (9) coded with the code sequence (7) is emitted, the transmission signal (9) being reflected at least partially on the medium (2) and received as a reflection signal (10) by a receiver (11), the reflection signal (10) and a signal (12) derived from the transmission signal (9) are subjected to a correlation analysis with a correlator (13) and a correlation result results, wherein a control and evaluation unit (15) correlates the correlation result with the time offset of the correlated signals and therefrom determined the medium level. The disadvantages of purely analogously constructed receive lines or purely digitally structured receive lines are avoided by the correlator (13) having an analog mixer (16) and the reflection signal (10) and the signal (12) derived from the transmit signal (9) with the analogue Mixer (16) are mixed into a mixer output signal, that the correlator (13) comprises an analog / digital converter (17) with which the mixer output signal is sampled and quantized to a digital mixer output signal and that the correlator (13) is a digital integrator (13). 18) with which a sequence of digital mixer output signals is digitally integrated into the correlation result.