Two sensors are fitted to every mussel, one on each shell half. A 250 kHz signal is sent to the first coil. This induces a voltage in the coil fitted on the opposite shell half, with a strength inversely proportional to the distance between the two coils. The strength of the voltage is a measure for the position of the shell. In order to avoid cross over between the various measurement signals, the voltages are transmitted individually, and are only read into the corresponding receiver (multiplexing).
For the purposes of reading in the induced voltage, the signal is rectified and digitalized via an A/D converter.
A microcomputer processes the data and ensures checking against the prescribed evaluation criteria.
Through internal evaluation, the occurrence of an alarm situation can be ascertained and indicated via the (potential-free) alarm contact.
Data, alarm reports and possible evaluation values can, if desired, be sent to the terminal port (RS422) to interface to computer or terminal. Using Present IT 3 software, this data can be stored and processed.