Electronic circuit for the processing of a measured value of a succession of vortices caused by a Karman vortex street

摘要

1. An electronic circuit arrangement for processing the readings obtained from the succession of vortices of a Karman vortex path, comprissing a) an emitter (1) in the form of an oscillator which energises an electro-acoustic transducer (2), b) a receiver (3), c) a demodulator (5) and an amplifier (6) which are connected in series with the receiver, as well as d) an evaluator circuit which incorporates a comparator (7) connected to the output of the amplifier (6) and having an adjustable trigger threshold for supression of interference signals and for conversion of sinusoidal input-signals into rectangular pulses, characterized in that the evaluator circuit furthermore comprises the following components : 1. a PLL circuit (9) connected in series with the comparator (7), for filtering a mean value out of the low frequency spectrum of the output signal of the demodulator, 2. a calculator branch (I) containing a computer and a printer branch (II) containing a printer, which are connected to the output of the PLL circuit in parallel with each other, 3. a frequency transformer array, which is preconnected in series with the computer (21) in the calculator branch (I), is adjustable, and comprises a first adjustable frequency-voltage converter (10) and a voltage-frequency converter (11), 4. a series connection comprising a second adjustable frequency-voltage converter (14) and an intergrator (18), preconnected to the printer (16) in the printer branch (II), as well as, 5. a control logic means (20) located between the computer branch (I) and the printer branch (II), which starts the printer after activation of the calculator only upon appearence of a reading derived from the succession of vortices of the Karman vortex path.