Abstract: The distinguishing of rain echoes from ground echoes is performed by an analysis of the attenuation of the radar echoes, a radar echo being classed as a rain echo if its attenuation on a logarithm scale as a function of distance fluctuates around an affine straight line according to a given statistical law.

Abstract: The distinguishing of rain echoes from ground echoes is performed by an analysis of the attenuation of the radar echoes, a radar echo being classed as a rain echo if its attenuation on a logarithm scale as a function of distance fluctuates around an affine straight line according to a given statistical law.

Abstract: A coherent pulse radar is activated successively according to at least two pulse repetition frequencies. These frequencies are of values such that (a) the received signal is ambiguous both with regard to distance and with regard to velocity, and (b) their ratio is reducible to the quotient of two integers which are preferably adjacent and have no common factors. For the frequency analysis, a number of samples is taken which depends upon the pulse repetition frequency, the numbers of samples associated with the two pulse repetition frequencies being, in relation to one another, in the ratio of the two integers. The distance/velocity resolution cell is then invariant with respect to the pulse repetition frequency; this permits removal of the ambiguity concerning mean information items appertaining to a long integration time.