Patent GB-1022186-A (GB)
Title: Improvements in or relating to chart position indicating apparatus
Inventor: ROBERTS GRAHAM ESTYN
IPC: G01S1/02
Filed: 1963-08-15
Abstract: 1,022,186. Selective signalling. DECCA Ltd. July 21, 1964 [Aug. 15, 1963], No. 32366/63. Heading G4H. [Also in Divisions G1 and H4] In position-indicating apparatus a sheet coated with material which changes colour, reversibly, when heated is arranged close to two sets of insulated electric conductors forming a two-dimensional co-ordinate frame, the conductors of one set forming a pattern of lines so that when any one conductor is heated by the passage of electric current the sheet material changes colour along a line representing a constant value of one co-ordinate, and similarly for the other, transverse, set of conductors, means being provided for selectively energizing one conductor in each set in accordance with coordinate input signal information corresponding to the position to be indicated. The invention is applied to signals derived from a " hyperbolic " radio navigation system. Temperature-sensitive materials.-The temperature-sensitive material may be (a) a double salt wherein, when the temperature is raised above a certain level, an ion exchange takes place between the two components; (b) compounds in which, when heat is applied, the shape of the molecule changes thereby changing the absorption frequency and hence the colour e.g. a cuprous sulphite-cupric sulphite com-, pound which changes from red to black at 45‹ C. and reverts to red when the temperature falls below 45‹ C. with a slight residual darkening which persists for some hours; or (c) a fluorescent paint. The material is applied as a coating on one surface of a paper sheet behind which the conductors are secured, a chart on a transparency being placed over the paper sheet, Fig. 5 (not shown). Electric conductor sets.-The insulated electric conductors may be arranged in cartesian or hyperbolic sets. Radio navigation, Fig. 1.-A receiver 10 is associated with a radio navigation system of the kind in which phase comparisons are made of the CW transmissions from spaced transmitters (" master " and " red," " green " and " purple " slave stations), see Specification 620,479. In the apparatus described, which is particularly for use by aircraft, phase angle information is sufficiently accurate if made to within a quarter of a cycle of phase change and therefore sine and cosine information from the phase discriminators in the receivers are used directly at the instants when they pass through zero magnitude, the phase angle information in quartercycle units being expressed in digital form. To select which two of the three sets of sine and cosine signals are to be digitized, a selector 15 is automatically controlled by the chart being placed in the display unit, Fig. 2 (not shown), e.g. by shaped edge-markings or photoelectrically as in Specification 914,185. Each digitizer 16, 17 produces a pulse when the sine and cosine input signal passes through zero and the pulse is stored on a capacitor until utilized. Digitizer, Fig. 3.-Inputs representing cosine A and sine A are applied to respective transistors 76, 86 having relay coils 77, 87 in their collector circuits. Relay 77 has change-over contacts 78, 79, employed for X and Y co-ordinate directions respectively; considering the X-direction contact 78 is connected during positive halfcycles of the input sine A signal to a source C and during the negative half-cycles to a source d, only one source being energized. Lead 80 is thus energized only during alternate half-cycles, and is connected to relay operating coil 81 having change-over contacts 82 ... 85; transistor 76 ensures that these contacts occur when the sine A signal input passes through zero. Capacitors 92 ... 95 are included, one for each of the four possible pulses per cycle. One, two or four pulses per cycle can be selected. The circuit arrangement for the Y-direction output lines 74, 75 is similar. The outputs of the digitizers are fed via a unit 18, Fig. 1, controlled by clock pulses occurring at a faster rate than the maximum possible rate of change of a quarter-cycle of phase, to accumulators 21, 22 each of which is an eight bit binary digital counter. For convenience in the display, translators 29, 30 convert the information in respective accumulators into two bit to radix sixteen; each translator has thirty-two output lines in two groups of sixteen, and comprises two relay " trees " one of which is associated with the four least significant, and the other with the four most significant, digits in the accumulator total, Fig. 4 (not shown). Each set of insulated electric conductors comprises 256 parallel wires, one bit of the two bit digit to radix sixteen being used to select one group of sixteen wires and the other bit selecting one of the sixteen wires in the group.