| 摘要 |
1,265,331. Radio receivers and transmitters. AGA A.B. 7 Feb., 1969 [7 March, 1968], No. 6689/69. Headings H3Q and H4L. A selective switching device comprises a plurality of manually operable switching members A, B, C, D operatively connected with primary circuit elements A1-D1, A2-D2, secondary circuit elements 1-16 selectively connected in circuit with the primary circuit elements by activation of a plurality of photocells P1-P4, an adjustable member AM for activating selected ones of the photo-cells, and a displaceable apertured screen member including a tape SM interposed between a light source LS and the photo-cells and connected with the adjustable member AM so as to be displaceable in response to the adjustable member. As shown, the device is used to select different wavebands in a radio transmitter-receiver of an aircraft. When a pilot approaches a certain airport he selects that airport by turning knob AM until the name of that air-port is seen in window DM. This rotation of knob AM moves the tape SM into position so that the apertures (AP, Fig. 3, not shown), corresponding to this airport are positioned between the lamp LS and the photo-cells P1-P4. There is a photo-cell connected between each crossing point of the primary and secondary circuits A1-D1, 1-16, so that the photo-cells which are energized through the apertures in the tape connect certain of the primary and secondary conductors to select the required waveband. It is arranged that by pressing push-button A the transmitter receiver is prepared to communicate with the control tower of airport A. If it is required to communicate with the control tower of another airport B then this airport is selected in window DM by rotating knob AM, this selects a different aperture arrangement on the tape SM and the push-button A is pressed. Similarly pushbutton B will operate the transmitter receiver differently depending on the aperture arrangement, i.e. airport selected. |
