| 摘要 |
The need often exists of accurately detecting the speed of flowing media such as, e.g., gases, in particular air, and liquids, and of initiating a control operation, regulating operation and/or a signal depending on whether a specific prescribed value has been overshot or undershot. For this purpose, it is proposed according to the invention to connect downstream of a sound generator (1) which generates a sinusoidal signal an analog switch (2) which is controlled by a clock generator (3) and is connected to a sound transducer (4, 5) forming at least one measurement section (6) and, with its output, to an amplifier (7), and the measurement section or sections (6) is/are assigned a reference section (8), which is located in a medium at rest and whose one sound transducer (9) is connected to the sound generator (1) and whose other sound transducer (10) is connected to an amplifier (11), there being arranged downstream of the amplifiers (7, 11) two comparators (12, 13), to which the two amplifiers (7, 11) are respectively connected, of which one (13) is controlled by the clock generator (3) whose output is led to a display (14), while there is connected downstream of the other compensator (12) an integrator (15) whose output is connected to the display (14) and/or to a voltage-frequency converter (19) and/or to a trigger (20) or the like. <IMAGE>
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