Abstract This paper uses a Fourier self-deconvolution method for improving the wavelength resolution in transmission experiments at continuous neutron sources utilizing a double-crystal monochromator device to probe as well as correct the generation of higher-order neutron scattering in a monochromatic neutron beam. The cold neutron radiography CONRAD-2 equipment has been utilized to resolve the steel transmission spectra of changing BCC phase and FCC phase fractions. Therefore, both low and high spectral resolution instruments with equivalent wavelength resolution have been proposed. The primary benefit of Fourier self-deconvolution is its ability to precisely narrow individual bands without modifying their relative position or the total band area. Thus, the resolution of the transmission spectrum has been improved by a factor of 3.16, and the info that the sample material comprises two crystallographic phases has been determined by the wavelength resolution improvement employing the deconvolution approach. Additionally, the slight variation in Bragg edge position for different phase fractions and the locations of the double phase Bragg edges have also been obtained using the ray-tracing simulation tool McStas. Steel’s resolving Bragg edge is put to the test in a high-resolution neutron wavelength-selection experiment at the European Spallation Source (ESS test_ beamline V20) using an equipment that utilizes neutron time-of-flight detection.