Patent GB-606887-A (GB)
Title: Improvements relating to apparatus for teaching aerial navigation by radio signalling
IPC: G09B9/26
Filed: 1945-02-13
Abstract: 606,887. Radio navigation trainers. LINK AVIATION DEVICES, Inc. Feb. 13, 1945, No. 3600. Convention date, May 18, 1944. [Class 40 (vii)] [Also in Group XIX] Relates to grounded aviation trainers for teaching the use of radio navigational signals provided with means for establishing a small scale electric field simulating the radiated field of a radio range and including a pick-up arranged for movement in the field in simulation of the movement of an aircraft. Means are described for simulating the A-N course signals, station identification signals, fan marker and Z marker beacon signals and noise, the component fields being alternating at frequencies equal to the modulation frequencies of the radio range. The instructor's microphone may be connected directly to the pupil's earphones for simulating airport control messages and for giving training instructions. As shown in Figs. 2, 3 and 5, the 1020 c/s. course signals are applied to an electrode system comprising four quadrantal annular members 32, 34, 36 and 38 connected to four quadrantal conical members 46, 48, 50 and 52 mounted under the recording table, Fig. 1 (not shown), so that the strength of the signal received by an electrostatic pick-up device mounted on the course recorder moving on the table simulates the field strength variations of a radio range. The signals applied to the two pairs of diagonally opposite quadrants 48, 52 and 46, 50 are keyed in A-N sequence by cam-operated switches', Fig. 4 (not shown), to produce equi-signal paths along the gaps 220 between the quadrants and the signals applied to the two quadrants of a diagonal pair are in anti-phase to produce a central cone of silence. After the completion of a given number of A-N signals, the 1020 c/s. signal is applied through preselected cam-operated stationidentification switches, Fig. 4 (not shown), first to the N quadrants and then to the A quadrants and the cycle is then repeated. The signal strength applied to the four quadrants is controlled by the four potentiometers 182, 182<1>, 174, 174<1>, Fig. 5, and a stronger signal controlled by the potentiometers 164, 164<1>, 154, 154<1> is applied to the pins 168, 168<1>, 158, 158<1> located in the centre to simulate the rapid increase and then decrease in field strength on approaching the cone of silence. The equisignal courses are adjusted by means of the potentiometers and each central pin, e.g. 168<1>, Fig. 3, is eccentrically mounted in a rotatable member, Fig. 10 (not shown), for adjustment of position. A 3000 c/s. signal is applied continuously to a centre pin 454 to simulate the Z marker beacon and the same signal is also applied through cam-operated coding switches to small elliptically-shaped plates 418, 428, 432, 436, Figs. 2 and 5 and Fig. 9 (not shown), mounted in the spaces between and projecting above the conical quadrants to simulate the fan marker beacons. The pick-up device comprises the inking wheel of the recorder (see Group XIX) and the output from the pick-up is mixed with a local source of noise and fed to the pupil's earphones, the intensity of the two components being controlled by a single volume control. The instructor's microphone is also connected to the pupil's earphones through an amplifier, the gain of which is automatically controlled by the intensity of the received navigational signals and a three-position switch is provided whereby the pupil can receive either or both navigational signals and the training instructions. A further switch is provided under the control of the instructor for connecting the microphone to the pupil's earphones irrespective of the setting of the pupil's switch. Specifications 370,128, [Group XXXIII], 476,816, 481,375, 484,243, [both in Group XXXIII], 569,440 and 606,886 are referred to.