US1792746A - Radio transmission system - Google Patents

Description

Feb. 17, 1931. KQLSTER 1,792,746

RADIO TRANSMISSION SYSTEM Filed Nav. 27, 1926 IN YEN T00 B, Freaer/a ,4. Ka/s/en M53; PM

A A TTORIJEYS Patented Feb. 17, 1931 v UNITED STATES.

PATENT. OFFICE FREDERIGK A. KOLSTER, F FALOALTO, CALIFORNIA, ASSIGNOR TO FEDERAL TELE-.

GRAPH COMPANY, OF SAN ERANGISCO CALIFORNIA, A

FORNIA RADIO TRANSMISSION SYSTEM Application filed November 27, 1926. Serial No. 151,061.

This invention relates generally to radio" systems such as are utilized for the automatic 7 transmission of signals.

It is an object .of this invention togdevise a system'of radio signaling for facilitating the piloting of ships.

It is a further object of thisinvention to devise a novel form of automatic beacon radio transmitter suitable for use on shlps; 10 It is another object of-this inventionto devise an improved system and apparatus for operating an oscillator-from a source of direct current.

Further objects ofthe invention will appear from the following description in which I have set forth the preferred embodiment of my invention. It is to be understood that p the invention is to be accorded a range of mechanical and electrical equivalents conslstent with the state of the prior art.

Referring tothe drawings, the single view. is a circuit diagram illustrating the pr1nc1-' ples of this invention.

In the past, radio equipment'upon ships has been limited to-radio" compasses and the regulation transmitting andreceiving equipment, and sirens or other sounding devices.

have. been relied upon to prevent collisions in fog. Sound-waves-how'everare not en tirely reliable for beacon'signaling since theyare apt to be intercepted by an inter-i mediatevessel and'because their intensityis not always an indication of the proximlty of the source. In thisinvention it is proposed to supplyeach ship with a small radiotransmitteradapted to automatically transmit a warning signal upon a definitewave length.

If two or more ships come 'sufliciently close 40 together to be within the range of theirrewith suitable receiving apparatus so that they will be able to pick up the beacon signals] transmitted from the other ship. According to the intensity of these signals they can judge the proximity of the other ship or by the use of a directional receiving equipment they can locate the approximate directionxas well as the distance. The individual beacon transmitters'are in the from of a small'oscilspective signaling equipment, the operators upon the respective ships willxbeprovided" lator operated from a direct current supply, a suitable interrupting device being em- CORPORATION- OF GAIiI- ployed for converting this direct current to alternating current at the desired signaling frequency. An automatic coding device is also employed so that the transmitter will" automatically transmit a certain signal at regular intervals.

Thus referring to the transmitter illustrated in the drawing, there is shown a small oscillator, preferably of the tube type, employing an electron emission tube 10 having the usual plate or anode 11, electron emission I element or filament. 12, and grid orcontrol.

electrode 13.. The plate or output circuit of the oscillator tube includes an inductance 14' which is tuned by means of capacitance '15,

and which is. coupled as by means of induc-.

ternating current from a suitableconverter designated generally at 20, which serves to convert the direct current to alternating current at a signal frequency of say from 500 to 600 cycles per second. This converter in its 7 preferred form comprises a transformer havmg a secondary winding 21 included in the output circuit of the oscillator tube 10, and

having apair of primary windings 22 and .23. These primary windings may for convenience be one continuous winding provided with a central tap 24. For alternately varying the current supplied to the windings 22 and 23, there is provided an interrupter which is preferably driven by a motor 26 supplied from the direct current lines Liandi L This interrupter is in the form of a-wheel" or disc 27 having a plurality of connected conductor segments 28 separated by a plurality of insulatingsegments 29. The stationary brushes or electrodes30 and '31'are arranged to contact with the segments and are connected to terminals of the windings 22 and 23. One side of the direct current line is connected to the central tap 24 while the other line is connected to the conductor segments 28. The brushes 30 and 31 are arranged so that one brush, say the brush 30, is leaving a conductor segment while the brush 31 is making contact with another conductor segment. Thus the successive energizing periods for the two windings 22 and 23 are overlapped, that is, before the winding 22 is deenergized winding 23 is energized. This arrangement practically eliminates all sparking between the brushes and the conductor segments since the increasing current in one winding as it enters upon its period of energization tends to neutralize or kill the field of the other winding. Thus when the current in a winding is broken there will be substantially no induced electromotive force to cause sparking. The speed of the interrupter wheel and the number of segments is such that the converter will impart to the oscillator a definite signal frequency in the neighborhood of 500 to 600 cycles per second.

In order to transmit modulated signals the energizing circuit for the windings 22 and 23 is interrupted according to any desired code combination. For this purpose there is provided a suitable code wheel 33 which is also driven from the motor 26 through suitable speed reducing gears indicated at 34:. A brush 35 contacting with this code wheel is connected to one side of the direct current line L while the code wheel is electrically connected with the conductor segments 28 of the interrupter wheel by means of a conductor path indicated by the dotted line 36. The code wheel is notched as at 37 so that at certain spaced intervals the converter will be energized to energize the oscillator, while for the intervals between signals the oscillator will be deenergized. In order to prevent the possibility of two transmitters being ex actly synchronized as to their code signals, the time interval between code signals is preferably made different for each transmitter as by a variation in the speed reducing mechanism 34 or a difference in the speed of the motor 26. Thus if signals of two transmitters become synchronized they will not continue long in this condition because of the difference in the frequency with which the code signals are sent out. The filament of the oscillator tube 10 is preferably energized direct from the direct supply lines L and L a suitable rheostat 38 being employed for controlling the filament current.

I claim:

1. A radio signaling system comprising a source of direct current, a transformer having its input supplied from said source, a motor also supplied from said source, an interrupter driven by said motor for varying the current supplied to the transformer at signal frequency, and a tube oscillator energized from the output of the transformer.

2. A radio signaling system comprising a source of direct current, a transformer having its input supplied from said source, an interrupter for varying the current supplied to said transformer at a definite signal frequency, a motor supplied from said source for driving said interrupter, a coding device driven by said motor and adapted to inter rupt the current supplied to the transformer according to a code combination, and an oscillator energized from the output of the transformer.

3. A radio signaling system comprising a tube oscillator having plate and grid circuits coupled together and an electron emission element in the form of filament, a source of direct current connected to said filament, a transformer having its input supplied from said source, an interrupter for varying the current supplied to the transformer at signal frequency, a motor for driving said interrupter, said motor being supplied from said source, and a coding device driven from said motor, said device serving to modulate the signal frequency in accordance with a code combination, the output of the transformer supplying energy to the plate circuit of the tube.

4. A high frequency transmitting system comprising a high frequency oscillatorincluding a three-electrode vacuum tube having a plate circuit, a transformer having its secondary winding included in said plate circuit, the primary winding of said transformer having two terminals and an intermediate tap, a source of direct current having one pole connected to said intermediate tap and the other pole connected'to a circuit path including two interrupters in series, one of said interrupters being operable to make electrical connections alternately with the two terminals of said primary winding, the other of said interrupters being operable to open and close the circuit through said primary winding periodically in accordance with a predetermined code signal to be transmitted, and an electric motor arranged to be operated by current from said source, said motor being drivingly connected to both of said interrupters for operating them simultaneously.

5. A system in accordance with claim 4 wherein the oscillator vacuum tube has a cathode connected to said direct current source for receiving heating current therefrom.

6. A radio signaling system comprising a vacuum tube having a cathode, an anode, and a control electrode, said cathode being adapted to be energized by current of low potential and the anode being adapted to have a higher potential impressed thereupon, a source of direct current of low potential connected to

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