Electronic circuit for processing the measured values from a vortex sequence produced by a Karman vortex path

An electronic circuit for processing the measured values obtained from a vortex sequence produced by a Karman vortex path, the circuit incorporating:

• (a) an oscillator which excites an electro-acoustic transducer and acts as a transmitter,
• (b) a receiver for receiving signals transmitted from said transmitter,
• (c) an amplifier connected in series with said receiver and a demodulator, along with
• (d) a data handling circuit for evaluating of signals received therefrom, characterized by
• (e) a comparator connected in series with said amplifier, the comparator having a trigger threshold for suppressing spurious signals and for converting sinusoidal input signals into square wave signals,
• (f) a PLL-circuit connected in series with said comparator for filtering-out a mean value from the low frequency frequency spectrum and for improving the pulse width-repetition ratio of the square wave impulses,
• (g) a parallel connected computer branch I and recorder branch II connected in series with the PLL-circuit,
• (h) an adjustable frequency transforming arrangement connected in series in the computer branch with the computer for balancing the circuit, and consisting of a frequency-voltage converter and a voltage-frequency converter,
• (i) an additional adjustable frequency-voltage converter connected in the recorder branch in series with the recorder and an integrator, along with
• (j) a control logic inserted between the computer branch and the recorder branch and which, after activating the computer, starts the recorder only when signals which can be evaluated are present.