GB750276A - Improvements in or relating to radar systems - Google Patents

Abstract

750,276. Radar. TELEFUNKEN GES., [formerly TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE]. Aug. 10, 1954 [Aug. 14, 1953], No. 23184/54. Class 40 (7). A pulse radar system capable of identifying a particular target includes at the target, means for deriving the pulse modulation from the received radar transmitter and for using it to modulate a reply transmitter and, at the radar, means for receiving the reply signals and using them in addition to the normal echo signals to provide a display on which the target can be identified. In a simple embodiment (Fig. 1, not shown), the normal echoes are used to give a P.P.I. type display and the reply signals, after compensation for any delay at the target and separate receiver at the radar, are applied to the same display to intensify the indication of the target. Alternatively, the reply signal may be used to vary the indicator tube focusing at the time of display of the corresponding echo signal or to produce a double dot indication ; it can also be displayed by itself on a separate display tube. In a second embodiment the reply signals received at E2 (which receiver may also form part of a communication link and is provided with a loud-speaker L for that purpose) are demodulated and fed to phase bridge P.B. The radar modulation signal is fed through phase compensator L.Z.G. and phase adjuster P.S. to a second input of bridge P. B. When the two inputs to the bridge coincide the local signal form P.S. is passed to unit I.G. which produces the distinguishing mark signal for application to the display tube S.A. Manual adjustment of the phase shifter P.S. to obtain coincidence may be facilitated by the provision of a visual indicator P.I., or a phase discriminator arrangement may be used to adjust unit P.S. automatically for coincidence. It may be arranged that the target transmitter can be switched on and off from the radar station. If it is required to identify more than one target each may have its own reply frequency and a display tube IT be provided fed from a frequency sweep receiver W.A. to indicate the frequency of each of the signals received. Receiver E2 may be adjusted to feed an identifying signal corresponding to one of these to the main display S.A.