Modeling of radio signal receiver detectors in the NI Multisim package

• Belous I.A.

  Vladivostok State University of Economics and Service
  Vladivostok. Russia
  Associate Professor, Chair of Information Technology and system

The process of functioning of demodulators of amplitude-modulated signals on the basis of a detector diode and analog multipliers together with a low-pass filter is described: the inclusion circuits and characteristics determining the quality of detection are given.

A brief review of publications on the use of synchronous reception and detection of amplitude-modulated signals in various fields is given.

Comparative modeling of practical and functional circuits of detectors of amplitude-modulated signals of the broadcasting standard is carried out. The most important characteristics are investigated: the detector characteristic and the coefficient of nonlinear distortions, taking into account the first ten harmonics in the output signal.

Computer simulation was carried out in the NI Multisim package, which allows simulating analog, digital, pulse and mixed electrical circuits and circuits.

It is shown that synchronous detectors of amplitude-modulated signals have a more linear detector characteristic, in comparison with detectors based on nonlinear elements. At the same time, demodulators, based on diodes, have a large slope of the detector characteristic. The comparison of the level of nonlinear distortions shows that synchronous detection has a much lower level of nonlinear distortion throughout the operational dynamic range.

 It is shown that the NI Multisim package has adequate models of electro-radio elements and macromodels of integrated circuits and, it is possible, to successfully simulate amplitude-modulated signal detectors. It is established that a synchronous detector can be successfully used in receiving devices of amplitude-modulated signals of the broadcasting standard, constructed by the criterion of sound quality with small nonlinear distortions.

Keywords: circuit simulation, detector, synchronous detection, detector characteristic, macromodel, amplitude modulation, frequency modulation.