Two direct TDOA geolocation approaches are proposed for FH(Frequency-Hopping) signals-the maximum likelihood direct geolocation and the maximum correlation-sum direct geolocation.The first approach makes use of the sparsity of FH signals in frequency domain

and constructs CCF(cross correlation function) matrix in frequency domain

the location estimate is obtained by searching the max eigenvalue of CCF in a two dimensional grid.The second approach directly uses the sum of CCF

and searches in a two dimensional gird to find the location estimate.The comparison between them has been made

and the first approach performs better than the second one

but needs much more computation.Monte Carlo simulations validate that the accuracy of the proposed maximum likelihood direct geolocation method is the best

and the maximum correlation-sum direct geolocation method also outperforms the two-step method.