Patent GB-778121-A (GB)
Title: Electronic plotting station for automatic plotting of one or more movable objects
IPC: G01C21/22
Filed: 1955-10-07
Abstract: 778,121. Air traffic supervision. STANDARD TELEPHONES & CABLES, Ltd. Oct. 7, 1955 [Oct. 8, 1954], No. 28619/55. Class 118 (2). [Also in Group XL (c)] In a system for displaying the plan positions of a number of aircraft as the positions on a screen of a corresponding number of distinctive luminous identification symbols, pairs of voltages proportional to the x and y co-ordinates of each aircraft are stored selectively in a corresponding number of storage devices in accordance with distinctive identification information and are applied sequentially to produce (1) an array of symbol charge patterns on the target of a storage cathode-ray tube R, Fig. 3, which is coupled to a projection C.R.T. V to produce a corresponding luminous display or (2) corresponding continuous D.C. voltages which position a corresponding number of optical projectors, Fig. 7 (not shown), each producing a luminous symbol. As shown in Fig. 3, the pairs of x and y coordinate voltages of the different aircraft are computed sequentially at F and applied to a plurality of storage devices H by a selector G controlled by signals from a unit B derived from aircraft identification signals. The devices H are shown as capacitors but are preferably magnetic stores. The stored pairs of x and y voltages are applied sequentially by two sections of a ganged multi-section switch I to the X and Y plates R<SP>1</SP> of a storage C.R.T. R and sawtooth waveforms P and Q, Fig. 4, are applied from generators P and Q to the deflection plates R<SP>1</SP> and to the deflection plates L<SP>1</SP> of a C.R.T. L whose luminous spot is focused on to a photo-cell N through a transparency M depicting a horizontal row of numerals 0-9. A generator J produces a plurality of recurrent groups of three contiguous selector pulses 1, 2, 3, the group recurrence period T being equal to that of the waveform P and the amplitudes of the component selector pulses of any one group being proportional to the three digits comprising the identification number, e.g. 297, of a particular aircraft. The outputs from generator J are applied to the X plates of the flying spot scanner L through three sections of switch I such that in any one position of switch I the output group of selector pulses corresponds to the identification number of the aircraft whose co-ordinate voltages are being selected by switch I and the beam of the scanner L is shifted by the selector pulses during each X deflection as shown in Fig. 5 to scan the three digits comprising the identification number, i.e. 297 as shown. The output from the photo-cell N modulates the writing beam of the storage tube R to produce a charge pattern representing the identification number 297, the position of said pattern being determined by the corresponding x and y co-ordinate voltages and a corresponding luminous display, Fig. 6 (not shown), is produced by applying the output from storage tube R through an amplifier U to a projection tube V which is scanned synchronously with the reading beam of tube R by time-base generators T and S. Additional symbols, e.g. letters and numerals, Fig. 10 (not shown), representing the aircraft radio channel, height and speed may also be displayed adjacent the identification symbol, such additional display being controlled automatically as above by signals transmitted from the aircraft or manually in accordance with information received from the pilot by radio. Enemy aircraft as detected by a P.P.I.radar can also be displayed on the screen by applying the radar video signals to another storage C.R.T. similar to R whose output is applied to the projection tube V. Alternatively, identification symbols, Fig. 10 (not shown), corresponding to groups of enemy aircraft may be generated and positioned as described above by means of corresponding x and y co-ordinate voltages generated manually by the radar operator and transmitted to the display unit by a telemeter system. Small portions of the main display may also be displayed on auxiliary small C.R.T.'s which are viewed directly. In the other embodiment, Figs. 7-9 (not shown), the outputs from the storage devices H are applied sequentially to a corresponding number of units producing corresponding pairs of D.C. co-ordinate voltages each voltage pair being applied to control the orientation of a respective optical projector producing a luminous image of the identification number on a screen. The x and y co-ordinates of an aircraft are computed in F, Fig. 3, from the range and bearing as determined by a ground beacon and airborne responder, Fig. 1 (not shown) (see Group XL (c)).