The method of detection of a broad-band signal by results of the parallel frequency analysis, working in the conditions of uncertainty concerning structural parameters of a signal and statistical parameters of noise is offered. Rearrangement of units of an initial periodogram is fulfilled by summation of signal strengths in a number successively going frequency channels. As function of the accessory formalizing an accessory of units of reformed set to the noise cluster, symmetric rational function is used. Service capability and effectiveness of the offered method are confirmed by outcomes of modeling, on a concrete example shown in comparison with analogue arrival of effect of magnifying of probability of a correct signal detection. A usage of the developed method - digital systems of detection of the broad-band signals, working in the conditions of uncertainty of structural parameters of a signal and statistical performances of noise.