Patent GB-353414-A (GB)
Title: Improvements in radio beacon and printing apparatus
IPC: H04L27/26
Filed: 1930-04-11
Abstract: 353,414. Type-printing telegraphy ; directive wireless signalling. SLEEPERRESEARCH LABORATORIES, Inc., 416, West 33rd Street, New York, U.S.A. April 11, 1930, No. 11601. Convention date, Jan. 14. [Classes 40 (iii) and 40 (v).] In a wirelessly-operated type-printing telegraph system the different characters are determined by the number of repetitions of audio-frequencies which modulate the carrier, and a radio beacon is combined with the system operated by two separate audio-frequency modulations. At the transmitter a motor 30, Fig. 1, drives a shaft 28 through a slipping clutch 31, wipers 29 and 34 on the shaft contacting with conducting segments 26 on one and 35, 36 on another insulating disc, the shaft being normally held stationary by the armature 32 of a solenoid 20 coacting with the toothed wheel 33 thereon. Two typical character keys 7, 8 are arranged, when depressed, to connect positive of battery 10 to one of the contacts 26 and also to break the circuit of solenoid 20 and thus allow the shaft 28 to rotate. This rotation proceeds until the wiper 29 reaches the live segment, whereupon the circuit of solenoid 42 is completed and an armature 43 is operated to stop rotation of the shaft. During this rotation the wiper 34 traverses a definite number of the contacts 35, 36, of which alternate ones are connected to two audio-frequency oscillators 39, 40 having frequencies I and II respectively ; these are brought into operation by the wiper 34 alternately to modulate the transmitter 49d. The operation of armature 43 also closes the circuit of an oscillator 45, producing a frequency III, after the signals corresponding to each character have been transmitted. The key 46 is adapted to send out a fourth audio-frequency modulation IV from the oscillator 49 to operate the carriage release at the end of a line, while the key 9 in association with one of the segments 26 is adapted to synchronize the transmitter and receiver mechanisms as described later. Details of the radio receiver are described, Figs. 3, 4, 6, 7, and 8 (not shown), and comprise filter circuits for the various audio frequencies associated with the printer and beacon and a change-over switch to utilize the type-printer or a loud-speaker for ordinary reception. The printing mechanism which is provided at both receiver and transmitter comprises a motor 102, Figs. 9, 10 and 11, driving a shaft 106 through gears 103, 104 and friction clutch 105. A type-wheel 107 is supported by a carriage 108 splined to the shaft and also supporting inking wheels 109, 110. The rotation of the shaft is controlled by a ratchet wheel 113, Fig. 15, with which co-operates a yoke 114 having arms 115, 116 reciprocated by means of magnets 117, 118 and the armature 119 connected to the yoke, the magnets being energized by the frequencies I and II alternately and allowing the type-wheel to rotate to the correct character. Static is said to affect both coils to the same extent and therefore causes no interference. The frequency III performs two operations, by energizing simultaneously the magnet 125 and the magnets 126. The latter operate a striker bar 127 which presses the paper 130 against the type-wheel ; while the former operates a rack 123, Fig. 14, coacting with a pawl 121 attached to the type-wheel carriage 108 to move it longitudinally one step along the shaft 28. A fixed rack 122 coacting with another pawl 120 prevents the carriage from retracting when the magnet 125 is de-energized. When the type-wheel carriage reaches its extreme right-hand position, the frequency IV is sent from the transmitter by the operation of key 46, and the magnet 149 of the printer is operated to raise the bar 143 and release the pawls 120, 121 from their respective racks. This allows the carriage to be pulled to the lefthand end by a weight attached to the cord 140 running over the pulleys 141, 142 and attached to the carriage. The tapered projection 137 on the carriage strikes a ratchet rod 138 co-operating with a ratchet wheel 139 fixed to the shaft of the paper roll 132 and moving the paper one line upward. The key 9 at the transmitter may now be depressed causing the type-wheel to rotate until a stop 150 on it comes in contact with a stop 151 on the bar 143. The radio beacon transmitter co-operating with the type-printing system comprises two angularlydisposed directional aerials 3, 6, Fig. 2, energized by carriers of the same frequency but modulated by frequencies V and VI from oscillators 1 and 4 or alternatively by frequencies I and II of the typeprinting apparatus if appropriate switching arrangements are provided. The receiver comprises angularly disposed coils 97, 98, Fig. 5, fed currents corresponding in strength to the audio frequencies V, VI respectively, and influencing a magnetic needle 99 moving over a scale 100. If a vehicle carrying the apparatus deviates from a course midway between the directions of the two transmitting aerials 3, 6 the needle 99 is deflected from its middle position. Specifications 354,749 and 355,216 are referred to.