Abstract: A pulse radar device which can sweep in the azimuth direction with a two element direction finding antenna (1, 2) having a fan pattern and wherein the path differences and Doppler frequencies are ranged selective to determine at each azimuth from the echo signals received a mean aspect angle (.epsilon.) and the azimuth maximum Doppler frequency which can be calculated therefrom. The mean aspect angles (.epsilon.) are determined according to the values of the measured Doppler frequencies with the equation .epsilon.=arc cos (f.sub.d /f.sub.dmax.alpha.). In this angle determination, smaller aspect angles are determined according to the measurement of the range selective determined path differences. Subsequently, an image point vertical deflection which is proportional to the aspect angle is utilized for perspective terrain display. The invention can be employed with pulsed radar devices on-board aircraft L for terrain display and for obtaining navigation data.

Abstract: A phase regulating circuit operating in accordance with the delay lock loop principle DLL for synchronizing the phase of a pseudo-random generator at the receiving end which is controlled by a pulse train oscillator and having two identical signal channels and wherein the inputs to the signal channels from the pseudo-random generator is rapidly switched between the two input mixers and wherein the output of the mixing networks is rapidly switched to a difference forming device so as to provide an output for the frequency control circuit of the pseudo-random generator.