Patent GB-729923-A (GB)
Title: Improvements in or relating to radar display systems
Inventor: MERCER ARTHUR KEITH
IPC: G01S7/20
Filed: 1952-04-24
Abstract: 729,923. Pulse radar. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. March 9, 1953 [April 24, 1952], No. 10375/52. Class 40 (7). In a pulse radar with a P.P.I. display the height of a target producing a response, e.g. b, Fig. 2, is also displayed by arresting the radial range sweep on receipt of the echo pulse, deflecting the beam from its arrested position b in a direction parallel to a radial height scale H by an amount bl proportional to the height of the target and then restoring the range sweep to its datum condition so that the beam traces a path b<SP>11</SP> parallel to the forward range ,sweep which intersects the height scale at a distance bl from the centre O, thereby indicating.the height; the height deflection is removed (thereby restoring the beam to the centre of the screen) before the commencement of the next range sweep. The height indication may be limited to responses displayed in a selectable sector or annular sector. The resultant range sweep waveform RV and height deflection waveform VW are shown in Figs. 3 (ii) and (iii) respectively. In one embodiment, Fig. 4, a pulse h, Fig. 3 (i), coincident with the echo pulse and of amplitude v proportional to the height of the corresponding target is produced by known means and applied to a circuit PL producing the deflection waveform VW which is applied to the height deflecting coil VDC which may be the normal shift coil or an additional coil. The duration x of waveform VW is determined by a pulse X of duration x produced in a generator RWG triggered by a pulse T coincident with the leading edge of pulse h and a pulse X is also applied to BU to brighten the portions b<SP>1</SP>, b<SP>11</SP> of the modified trace. The normal range sweep waveform, Fig. 3 (iv), is applied to the radial deflection member RDC and is produced by a generator TB gated on by a pulse R from a generator TBWG triggered by a pulse S, additional outputs from TBWG being applied to BU and to PL to black out any signals received after the termination of the sweep and to prepare the circuit PL for the next height pulse h. On receipt of a height pulse h a pulse T2 coincident with the leading edge thereof triggers generator RWG2 producing a pulse Y of duration y which is applied to a control circuit TBC to modify the 'range sweep waveform to the form RV. The height indication may be limited to a selectable sector indicated by azimuth markers and it may be limited to targets above a selectable minimum height or beyond a selectable minimum range. In some cases, e.g. response a, Fig. 2, the cathode beam is deflected off the screen and in order to avoid confusion the height scale and coil may be rotated through 90 or 180 degrees. In a modification, the circuits PL and RWG are omitted and replaced by a generator SG producing pulses SVW, SX and ST2, corresponding to pulses VW, X and T2, the timing and azimuth of these pulses being controlled manually by adjustable range and bearing markers or automatically by the first echo pulse received within an annular sector defined by adjustable range and bearing markers.