In the postprocessing of open-loop radio science receiver (RSR) data, the frequency of a received signal is reconstructed and its amplitude estimated. Three types of algorithms can be used for the signal detection: a digital phase lock loop (PLL), fast Fourier transform (FFT) alone, or FTT with an optimization. One optimization, referred to as spectral analysis, is compared with the PLL and FFT detection methods especially for the case of signal with high-frequency dynamics. The reconstruction procedure is an important first step of processing radio science experimental data since its accuracy influences the resulting science observations. The comparisons deduce that the spectral analysis is superior for the cases of high dynamics signals.