Abstract: A device for estimating the scanning frequency of an unfriendly tracking radar of the conically scanning type comprises input circuitry for eliminating the d-c component of a detected radar signal and a sampler deriving a train of amplitude pulses from that signal which, after digitization, are fed to a calculator performing a Fourier analysis thereon. The index of the term of the resulting Fourier series with the largest sum of the absolute values of its real and imaginary coefficients is selected and weighted with a corrective factor obtained from the numerical values of the coefficients of a limited number of preceding and succeeding terms in the series; the corrected index yields the estimated scanning frequency.