A new method is proposed to detect the number of signals and estimate their Directions-of-Arrival (DOAs) in the multipath channels. Based on the coherency among signals, multiple independent sources resulted from multipaths are automatically divided into several independent groups from the multistage Constant Modulus array with power signal detector, and the spatial signature corresponding to each group is estimated. Then the problem for combined detection and estimation is transformed into solving for the coherent signals from each spatial signature and finally handled by utilizing the invariance property of noise subspace. The proposed method not only can deal with the situation where there are more incident signals than sensors in the array, but also is applicable to arbitrary array geometry. Effectiveness of the method is demonstrated by computer simulations and water tank experiments.