Analysis of methods for demodulation of free induction decay signal that are suitable for use in pulsed nuclear quadruple resonance radiospectrometers was performed. The structure and MATLAB Simulink model of the receive path of radiospectrometer was synthesized, in which the Software Defined Radio technology was chosen for the implementation of a quadrature detector with a filtration and quadrature reflection suppression system. The application of the principle of direct digitization of the signal made it possible to significantly reduce the length of the analog portion of the receiver, and, consequently, reduce the noise of the useful signal and the level of out-of-band higher order spectral components.