The monostatic coherent radar interferometer technique which has been applied in the past few years to studies of short-wavelength plasma turbulence in the earth's ionosphere can provide, in addition to the Doppler spectrum, estimates of mean size, mean angular position, and velocity transverse to the viewing direction. Here we describe the conversion of an inexpensive bistatic 50-MHz continuous wave (CW) Doppler system to an interferometer designed to investigate short-term dynamics of high localized scattering regions in the Auroral ionosphere, with mean transverse sizes in the range from about 0.5 to 5.0 km. Preliminary analysis shows, at times, high-coherence echoes, of type I or type III, to originate from localized, strongly unstable regions which are related to dynamic source regions of transient nature with mean azimuthal sizes possibly less than 1 km. Our observations suggest that the CW Doppler system, which provides high-quality spectra and excellent temporal resolution, has its measurement capability enhanced significantly when operated as an interferometer, becoming a powerful tool for studying short-term temporal and spatial variations of electrostatic turbulence in the auroral plasma. ¿ American Geophysical Union 1988