Calibration mark transmitter

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A calibration mark transmitter is an electronic device that is used to test analog receivers . The output signal of the calibration mark encoder consists of very short pulses (a few ns) with a precise repetition frequency (e.g. 10 kHz, 100 kHz, 1 MHz). The spectrum of this signal consists of lines spaced at the repetition frequency.

If a calibration mark transmitter is connected to the antenna input of a receiver , you can receive signals ( whistling signals ) at intervals of the repetition frequency when turning the frequency scale and thus check the scale. If the amplitude of the individual spectral lines is known, the sensitivity of the receiver can also be assessed.

Modern receivers with digital frequency setting have such a high setting accuracy that checking with the aid of a calibration marker is no longer necessary today.

A calibration mark encoder consists of a quartz-controlled oscillator that oscillates at a "round" frequency (e.g. 8000 kHz). The frequency is divided down with a frequency divider (e.g. divider by 80) to the desired repetition frequency (e.g. 100 kHz). In a subsequent stage, very short, needle-shaped pulses are generated, the spectrum of which consists of a large number of lines spaced apart from the repetition frequency. Depending on the rate at which the pulses rise, signals up to the 10 GHz range are generated.

literature

  • Birger Qvarnstrom (Ed.): Instruments and Measurements. Academic Press, New York 1965.
  • Burkhard Kainka: Tube projects from 6 to 60 volts. Elektor Verlag, Aachen 2004, ISBN 3-8957-6142-7 .

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