In this paper we propose a method for estimating the parameters of frequency-hopping (FH) signals embedded in noise. The method is based on two main steps: i) representation of the signal in the time-frequency domain; ii) integration in the time-frequency domain along paths expressed in a parametric form depending on the parametric law characterizing the signal instantaneous frequency. The method does not make any assumption about the alphabet of hopping frequencies, the duration of each hop, or the synchronization. The performance of the method are given in terms of estimation variances.