Doppler asymmetric spatial heterodyne spectroscopy(DASH)is a new technology for measuring upper atmospheric winds by observing the Doppler shift of atmospheric emission lines from a satellite using a limb viewing geometry.The real-fringe DASH interferometer is a modification of conventional DASH interferometer; it keeps the advantages of the conventional one.Moreover,this interferometer will not need exit optics to image the superposed fringes onto the detector; it will be more compact and lightweight,making it suitable for space-based platforms.We describe the concept of the new interferometer and present the exact expression of spatial frequency and phase of the interferogram.We also describe design and simulation of a real-fringe DASH interferometer for observation of the O [1D] 630nm emission.The simulation results agree with the theory.