GB1505430A - Coherent pulse-doppler radars - Google Patents

Abstract

1505430 Radar INTERNATIONAL STANDARD ELECTRIC CORP 18 Aug 1976 [22 Aug 1975] 34456/76 Heading H4D A pulse doppler radar is described including a non coherent transmitter, e.g. magnetron 1, feeding an antenna with pulses whose carrier # 0 has phase and amplitude variations, a first mixer 6 receiving the transmitted signal E(t ) and a signal # OL from a stable local oscillator 7 to give the frequency shifted transmitted signal E'(t) of frequency # O -# OL , and a secon mixer 9 receiving the signal R(t) of frequency # O Π# D (# O = doppler shift) reflected from an object and the signal # OL to give the frequency shifted echo signal R'(t) of frequency # O Π# O -# OL . A first phase discriminator 12 measures phase shift Z(t) between E't and quadrature signals from a stable reference oscillator 11, the phase shift being averaged over the pulse to give quadrature averages Z 1 =A o Cos# o , Z 2 =A o Sin # o . A second phase discriminator 14 measures phase shift W(t) between R'(t) and the reference quadrature signals, the phase shift being averaged over each range increment to give quadrature averages W 1 = A Cos #, W 2 =A Sin #. A calculator 16 receives the signals Z, and Z 2 as stored during the receiving phase at 17 together with signals # 1 and # 2 to give results i.e. independent of the transmitter phase and amplitude variations. A digital version of the radar is described, Fig. 2 (not shown), together with details of the calculators 16, Figs. 3, 4 (not shown).