1. A continuous-emission radar detection method, a propagation delay for a useful target situated at a maximum radar range being greater than a duration of an elementary ramp, said method comprising: generating a frequency-modulated continuous signal, an emission sequence being formed of successive and contiguous ramps, of excursion ΔF and duration Tr, which are centred on a carrier frequency F 1 ; simultaneously and continuously receiving from at least one target an echo corresponding to the signal emitted, delayed by a propagation time for an outward-return journey to the at least one target kTr+θ, k being an integer and θ a duration less than Tr; demodulating the signal received by the signal emitted, resulting in a signal being composed for each emission ramp of a first section of sinusoid at a frequency δFdim=(1−(θ/Tr))·ΔF and of a second sinusoid at the frequency δFd=(θ/Tr)·ΔF; sampling at the each emission ramp, in a continuous manner and in synchronism with the emission signal, the resulting signal, a start and an end of each sampling sequence being chosen respectively at the start and at the end of the each emission ramp; performing a first digital Fast Fourier transform (FFT), on the resulting signal, at each sequence corresponding to the duration of an emission ramp; performing a vector sum of two spectral lines appearing at the frequencies δFd and δFdim on output from the FFT, after resetting them into phase with respect to one another; and performing a detection by comparing modulus of the vector sum with a predetermined threshold.