US1776065A - Method of and system for radiosignaling - Google Patents

Description

Sept. 16, 1930. E; L. CHAFFEE 1,776,065

METHOD OF AND SYSTEM FORRADIOSIGNALING Filed Aug. 29. 1322 MflDUL A TOR awvemtoz Patented Sept. 16, 1930 EMORY LEON CHAFFEE, OF BELMONT, MASSACHUSETTS, ASSIGNOR TO JOHN HAYS HAMMOND, JR., 0F GLOUCESTER, MASSACHUSETTS METHOD OF AND SYSTEM FOR RADIOSIGNALING Application filed August 29, 1922. Serial No. 584,959.

This invention relates to methods of and systems for transmitting intelligence by radiant energy and has for some of its objects the provision of an improvedmethod and means for transmitting a message without interference by others; the elimination of effects of static and other atmospheric strays; and the provision of a plurality of message channels over which the message may be transmitted in variously characterized forms, whereby the message may be transmitted over any of the channels independently of the other or others. Still other objects of the invention will appear hereinafter.

In the drawings there is shown diagrammatically so much of a radio system embodying the present invention as is necessary to an understanding of the present invention.

Fig. 1 represents a transmitter and Fig. 2 represents a receiver.

In systems for radiant signaling it has been the practice to provide means at the sending station for modulating a fundamental frequency or carrier wave, commonly known as the A frequency, by a second oscillating current commonly designated the B frequency. The B frequency current may be a current of voice frequency, that is, may be produced by a usual telephone transmitter in accordance with voice waves. It is understood that the system of the present invention may employ such a sender which is shown, for example, in Fig. 1, provision being made for the production of a plurality of A frequency currents 1, 2, etc, of relatively different frequencies, all modulated in accordance with the same B frequency. In the specific embodiment shown and described for the purpose of illustration a pair of channels is provided and it is understood that the phase of modulation at the sender is to be opposite so that the modulation frequency efiects at the receiving station are'additive, in the filter circuit. This will be more fully brought out in the following detailed description of the receiving apparatus.

Referring to Figure 2, there is shown so much of a so-called wireless receiving systern as 1s necessary to an understandmg of the invention. As shown, the sald recelvlng denser 13, by which it may be tuned to one of the A frequencies. The circuit 12 of the loop 10 is operatively connected to a three electrode thermionic device 14 having a usual heated filament 15 forming a hot cathode for emitting electrons, a plate 16 upon which the electrons impinge, and a grid or potential gradient varying means 17 for controlling the passage of electrons. The grid or input circuit is thusarranged to be controlled by electrical oscillations in theloop 10 and. the oscillatory circuit 12. In series with the grid or input circuit there is provided a blocking condenser 21 and a usual grid leak resistance whereby the device 14 is caused to operate as a detector.

Similarly, the loop 11 forms part of a closed oscillatory circuit 18, including an adjustable condenser 19 by which it may be tuned to the other one of the A frequencies. The circuit 18 of the loop 11 is operatively connected to a second'three-electrode' thermionic device 20 similar to the device 14 and having a usual filament 15, plate 16 and grid 17. The grid or input circuit of the device 20 is arranged to be responsive to the electrical oscillations in the loop 11 and closed oscillatory circuit 18. In series with the grid circuit there is provided a blocking condenser 22 and usual grid leak resistance whereby the device 20 is caused to operate as a detector. A-filament heating battery 23 serves to incandesce the filaments '15 of the thermionic devices 14 and 20.

The output circuit of the thermionic device 14 includes a winding 30 of a transformer 31 and a plate potential battery 32. The output circuit of the thermionic device 20 includes another winding 33 of thetransformer 31 and also the plate potential battery 32. The plate potential batter 32 determines thenormal plate voltage the plates 16.of the devices-14 'and 20, its polarity being such that said plates are positive with respect to the hot cathodes. A

third winding 34 of the transformer 31 forms part of a filter or resonant circuit 35 which as shown includes a suitable condenser 36 and a winding 37 of a second transformer 38. The capacity of the condenser36 and the inductance of the windings 34 and filament 15 and plate'16. A filament heating battery 42 is arranged to incandesce the filament 15. A condenser 43 is provided in the grid or input circuit of the device 41 for a purpose which will be subsequently set forth. The output or plate circuit of the thermionic device 41 includes an indicating device 44, a plate potential battery 45, and a winding 46 of a transformer 48. The potential of battery is such that the plate 16 of the device 40 is made positive with respect to the hot cathode. A by-pass condenser 47 is provided in shunt with the indicating device 44 for currents of relatively high frequency. The secondary winding 49 of the transformer 48 is included in the grid circuit of the device 41 for feeding back energy thereto. 1

nthe operation of the embodiment shown in Figure 2 the sending station impresses on the ether a plurality of fundamental or A frequencies, differing from each other and modulated in accordance with the same B frequency current which may be super audible or may be an ible as in voice modulation). -The respective oscillations produce currents in the coils 10 and 11, and these currents are respectively rectified or detected by means of the thermionic devices 14 and 20. .The rectified or detected currents flow through the respective windings I 30 and 33 of the transformer 31, the direction of winding being such that they produce additive effects upon the winding 34.

A local currentflows in the filter circuit 35 I 'which is inductively coupled to igqe winding 40 of the transformer 38 and t s to the input circuit ofthe thermionic device 41. The windings 46 and 49 are arranged so that energy is fed back from the plate or outplut circuit of the amplifying device 41 to t e input or grid circuit. If the modulation frequency is super audible device 41 isvused as an autodyne. The frequency of the current fed back is then such that it dif fers from the frequency of current flowing in the filter circuit 35, by a relatively small amount, there being thus produced a series of beats which are sufliciently low in fre-' .ing 40.

It will be seen that the effects of the true message currents are additive in the circuit 35 while the effects of strays and static disturbances will be subtractive. true message will'be reliably received with substantially no interference thereto by strays or static disturbances, or by other. interfering messages.

Thus it will be seen that I have provided a receiving system for receiving telephone or telegraph messages which is-essentially proof against interference from atmospheric stra s or so-called static or other radio .distur ances. Furthermore, the system provides two channels through either of which the message is received, each of said channels being adapted to receive the message independently. Danger of block by malicious outsiders is thus minimized since each of the Thus the channels will operate independently of such outside interference to actuate the indicating device, and thus the message will be received in spite of the attempted interference. Furthermore, the system is relatively free from 00 interference by strays or so-called stat1c. 1

Illustrative apparatus and circuits have been shown for the purpose of showing some of the ways in'which the invention may be practiced; but it is expressly understood that the scopeof the invention is not to be limited thereby, reference being had to the appended claims for that purpose.

What is claimed is 1. A method of electrical communication which consists in transmitting two series of wavesmodulated in opposite phase relation, receiving said series'of waves, producing at the receiver currents corresponding in frequency with said modulations, additively combining said currents, and indicating them.

'2. A method of electrical communication which consists in transmitting two series of waves modulated in opposite phase relation, impressing signal variations on the modulated series of waves, receiving said series of waves, producing at the receiver currents phase for each of said series of oscillations,

means for demodulating said series of oscillations to produce currents corresponding 1n frequency with the modulations thereof,

means for additively combining said currents, an indicating device, and means for causing said combined currents to actuate said device.

A. A radio receiving system comprising two channels for the reception respectively of two carrier waves having unlike frequencies and modulated in opposite phase relation, a detector operatively connected with each of said channels, an indicating device operated by said detectors, and a filter circuit connected oppositely to the output circuits of the detectors and interposed between said detectors and said indicating device for permitting the "passage of currents of a selected frequency band.

5. A radio receiving system comprising a plurality of channels for the reception of a plurality of carrier waves having unlike frequencies and modulated at the same fre quency but in different phase relation, a detector operatively connected with each of said means, an indicating device operated by said detectors, and a single filter circuit differentially connected with the output sides of the detectors and interposed between said detectors and said indicating device, said fil-v ter circuit being responsive only to a predetermined frequency band.

6. A multi-channel radio receivingvsystein comprising a pair of loops arranged at an iii) angle of substantially 90 to each other and at angles of substantially 45 to the direction of propagation of a signal wave, a corresponding pair of closed, oscillatory circuits each including one of said loops, a detector operat'ively connected with each of said closed, oscillatory circuits, an indicating device operated by said detectors, and a filter circuit interposed between said detectors and said indicating device.

7. In a receiving system for radiant energy, a plurality of receiving channels tuned to energy of difierent frequencies respectively, means for producing currents of like frequencies but of different phases from the received energy, an indicating device, and

means interposed between said channels and the indicating device for causing said currents to combine additively and to simultaneously actuate said device.

- 8. A method of wireless communication which consists in transmitting twoseries of waves having unlike frequencies and modulated in opposite phase relation according to a single series of variations impressed thereon, receiving and detecting the energy of each of said waves independently, additively combining the currents produced by said detection, combining the resultant current-with current of a different frequency to produce beat currents, and indicating the beat currents.

9. Means for receiving the energy of a plurality of waves modulated in out-of-phase relation accordingto a single series of variations, comprising an indicating device, means for producing currents from said waves of frequencies corresponding to said variations and of similar out-of-phase relation, and means for additlvely combining said currents to actuate said device and for differentially combining the effects of other waves.

10. Means for receiving the energy of two waves modulated in opposite phase relation according to a single series of variations, comprising an indicating device, means for producing currents from said waves of frequencies corresponding to said variations and of opposite phase relation, and means for additively combining the energy of said waves to actuate said device and for differ entially combining the effects of other waves.

11. Radio receiving apparatus selectively responsive to the energy of two Waves difiering in a frequency characteristic and each modulated in opposed phase relation by a single signal current, comprising an indicating device, means for producing currents from said waves of frequencies corresponding to the frequencies of modulations of the waves, means for impressing said currents on the indicating device cumulatively, and

means for differentially combining the energy of waves otherwise modulated to effectively prevent the actuation of said device thereby.

12. Radio receiving apparatus selectively responsive to the energy of two waves differing in a frequency characteristic and each modulated in opposed phase relation by a single signal current, comprising an indicating device responsive to the energy of such waves, means for producing current from said waves of frequencies corresponding to the frequencies of modulations of the waves, means for causing said currents to operate the indicating device, and means for differentially combining the energy of waves otherwise modulated to effectively prevent the actuation of the indicating device thereby.

13.- A method of electrical communication which consists in transmitting a plurality of series of waves modulated in out-of-phase relation, receiving said series of waves, producing at the receiver currents corresponding in frequency with said modulations respectively and additively combining said currents to produce a signal, but differentially combining the energy of waves not so characterized.

14. A method of electrical communication which consists in transmitting two series of waves modulated in out-of-phase relation, receiving said series of waves, producing at the receiver currents corresponding in frequency with said modulations respectively and additively combining said currents to produce a signal, but difierentially combining the effects of static.

15. In a system of radio communication, 7

a pair of radio transmitters of difierent radio frequencies, modulating means afi'ecting the two transmitters in opposite senses, means for radiating differentially modulated waves *of the two frequencies, receiving and integrating means discriminating between the two transmitted frequencies and means for applying the integrated currents in opposite senses to a common receiver whereby the difierential modulation acts cumulatively on the receiver.

16. In a transmitting system for radiant energy, two radio frequency generators simultaneously emitting waves of different frequencies, a telephone transmitter, and means operated by the telephone transmitter for modulating the two transmitted waves simultaneously in opposite senses.

17. The method of transmitting and receiving radio intelligence which consists in generating and radiating two waves of different radio frequencies, modulating these waves 1n opposlte sense, separately recervmg the waves of different frequencies and combining their effects in opposite senses to produce a cumulative result.

In testimony whereof I hereunto afiix my signature.

EMORY LEON CHAFFEE,

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