Patent ID: 7487057

Claim:
Field device electronics connected with a sensor unit for process measurements, wherein the connection exists over corresponding signal paths, and wherein analog measurement signals (S 1 ) of the sensor unit are received and wherein analog drive signals (S 5 ) are produced for the fundamental wave excitation of the sensor unit and wherein said analog drive signals (S 5 ) are transmitted to the sensor unit ( 4 ), comprising: an analog/digital converter for producing the analog drive signal (S 5 ), a digital phase shifter; and a digital/analog converter, wherein: said sensor unit is embodied as an active electromechanical transducer; said active electromechanical transducer produces an analog measurement signal (S 1 ) for determining and/or monitoring a fill level of a medium in a container; the analog measurement signals (S 1 ) are digitalized by said analog/digital converter and forwarded to said digital phase shifter, and an output signal (S 4 ) of said digital phase shifter is converted by said digital/analog converter into the analog drive signal (S 5 ) for the sensor unit; said digital phase shifter includes a ring memory; the values of the analog measurement signal (S 1 ) are written sequentially into memory locations of said ring memory; the phase shift of the drive signal (S 5 ) with respect to the analog measurement signal (S 1 ) is achieved by reading a value, which is output from said digital phase shifter, out of a memory location of said ring memory which is located a predeterminable number of memory locations before or after the memory location in which a currently read-in value is store; said active electromechanical transducer is embodied as an oscillating fork having a drive unit and a detector unit, said detector unit produces the analog measurement signals (S 1 ) and feeds them to the field device electronics, and the analog drive signals (S 5 ) are transmitted from the field device electronics to said drive unit; and the predeterminable number of memory locations represents a determined phase shift angle.