US1388450A

US1388450A - Transmission of intelligence

Info

Publication number: US1388450A
Application number: US48789A
Authority: US
Inventors: Edwin H Colpitts; Arnold Harold De Forest
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1915-09-03
Filing date: 1915-09-03
Publication date: 1921-08-23
Anticipated expiration: 1938-08-23

Description

E. H. COLPITTS AND H DE F. ARNOLD.

TRANSMISSION OF INTELLIGENCE. v APPLICATION FILED SEPT 3, I915. RENEWED IAN. I3, I92I.

Patented Aug. 23, 1921. *Wwv- MW Q I s: Q q

/n I/enfons:

' tions in message wavds-of 'comparativelylow' quired high frequency, but of a power value I UNITED STATES. PATENT "oFFrc-E.

EDWIN n. coLrrr'rs, or nasal omen, Am) HAROLD DE ronns'r ARNOLD, or Maren- WOOD, NEW JERSEY ASSIGNORS, BY MESNE ASSIGNMENTS, TO WESTERN ELEC- TRIO COMPANY, INC0E1ORA-TED,- A. CORPORATION OF NEW YORK.

TBANSMIsSION OF INTELLIGENCE.

Specification of Letters Patent.

Patented All. 23, 1921..

Application filed September 3, 1915, Serial No. 16,78 9. Renewed January 13, 1921. Serial No. 437,125.

To allwitomc't may concern: 7 v 7 Be it known that we, EDWIN H. CoLrrrrs and Harrow Dn Fonnsr ARNOLD, citizens of the United States, residing respectively at East Orange, in the county of Essex and State of New Jersey, and Maplewood, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in the Transmission of Intelligence, of which the following is a full, clear,

concise, and exact description.

This invention relatesto the transmission of intellligence, and more particularlyto systems in which sustained oscillations'of high frequency are employed as carrier waves, and in which the amplitude of such oscillations is made to vary .in accordance with variafrequency.

Its object is the production of high frequency waves which are are accurately modulated in accordance with the messagewave and of sufficient power for effective long distance communication.

To these ends the invention provides for the generation of carrier waves of the recomparable with that of the message impulses, as distinguished from that ultimately required for effective transmission. It further provides for modulating or changing the amplitude of these oscillations of low power in accordance with the form of the message wave and for amplifying the power value of the modulated high frequency oscillations to -a degree suificient for long range communication.

The arrangement of this invention makes it possible to use, as the low fre uency message source, a telephone transmitter or other device capable of handling only a small amount of energy, whereas in previous systerns it has been assumed that for effective long range'communication it was essential that the low frequency-message source should be one capable of handling an amount of power comparable with that necessary for radiation.

In other words, the power value of the generated oscillations is chosen with reference' to the power delivered by the primary modulating source rather than with reference to the amount of power necessary for radia tion. I Y

, The invention will be more clearly understood byv reference to the accompanying drawing, in which Figure 1 represents the system of this invention arranged for radio telephonic transmission; andFig, 2 shows an improvement on the system of Fig. 1, in-

which are the inventions'of others and which have been made the subject matter of other plifier 3 includes the anode 5, condenser 10,

primary winding 11 of transformer 12, Wind ing 13 of transformer 14, condenser 15, bats 'corp'orating certain specific modifications amplifier includes the cathode l, the electrode 1 Y K tery 16and the cathode 4. An impedance coil 17 is inserted, as shown, to provide a.

direct current path for space current supplied to the amplifier 3 by the battery 16.

Secondary winding 18 of transformer 14.

is bridged across the cathode 4 and electrode 6, as shown, and serves to feed back, into the input circuit of the amplifier, currents generated inthe output circuit, thereby causing the amplifier 3 to function as a generator of high frequency oscillations, the periodicity of which is determined by the adjustment of condensers 10 and 15. For a more complete understanding of this action, reference may be had to the Colpitts Patent 1,137,384:.

Primary winding 19 of transformer 8 is connected through another transformer 20 to a source of low frequency impulses, which in thiscase comprises a telephone transmitter 21 and a battery 22. By this arrangement the telephonic electromotive forces, generated by transmitter 21. in the winding 7, serve to vary the amplitude of the high frequency oscillations produced by the amplifier 8, and cause to be impressed on the transformer 12 a wave impressed.

I amplifiers 27, 28 and 29.

25 be made to produce either fication or a current amplification, are discussed in the Arnold Patent No. 1,129,942

35 which forms with it 65 frequency action of the system. The resistance 25, in

, parallel withthe condenser 24 andthe wind-- ing 23, is included in the input circuit of an amplifier 26, also ofthe thermion-ic type.

Amplifier26 serves in the Well known manner to amplify the power value of the modulated high frequency oscillations produced by the amplifier'3. In'this case, this power.

amplification isdirected mainly to increasing the oltage of the modulated high frequency to the degree necessary -for controlling the input circuits of the high current The features of,design, whereby a thermionic amplifier of the type in question may a voltage ampliof March 2, 1915, and the 1,329,283 of January 27, 1920.

The'output circuit of" amplifier 26 includes Arnold Patent the inductance 30 for providing a direct current path for the space current delivered to-the amplifier 26 by battery 31. In multiple with the inductance 30 is a condenser 32 an anti-resonant circuit tuned to the frequency of the high frequency oscillations, and consequently of high im; pedance thereto.

Theinput circuits of the

current amplifiers

27, 28 and 29 are bridged in multiple across the terminals of condenser 32. This and also other arm ments for producing the same result are isclosed in the Arnold Patents, 1,129,942 and 1,129,943 of March 2, 1915. In the present case, the cathodes,

33, 34-and 35 are connected in series with a battery 36 and an The common output circuit of the ampli-.

fiers

27, 28 ,and 29 includes winding 38 of, the output transformer 39' and -a. sourceof direct current, which, in this case, is shown, as a direct current generator 40, though it is obvious that any 'other sourceof direct current may be employed. A condenser 41 is preferably shunted'about the terminals of the generator 40 in order to furnish a low impedance path for the l1igh-frequency.cur-

rents. The secondary winding42 of the transformer 39 is connected in series with the antenna 43, and serves to'impress thereon high currents of large power value This resistance serves as a from an antenna but of a adjustable resistance 37 and are heated to the required degree of incandescence by current supplied from this 50 battery. this case the output amplifiers 26 is coupled by the winding 57 .to the resonant circuit made'up of the windmodulated in accordance with the telephonic wave generated by transmitter. 21.

The'amplifiers 27, 28 and 29 are preferably of thehigh' current type described in the Arnold Patent No. 1,129,942 and in Arnolds application-,gSer-ial No. 277,578, filed February 17,1919, and while, for the sake of illustration, only three of these amplifiersare hereinlshown, it has been .found in practice thatany number of such amplifiers may beconnected in multiple, depending upon the amount of power required, an

that two or three hundred of such amplifiers connected in multiple produce a power amplification suflicient for effective long range communication.

frequency oscillations is employed. In this case, the high frequency oscillations are generated 'in a separate thermionic amplifier '50, whose operation will befound described in patent to Hartley 1,356,763, patented October 26, 1920, and which is designed to generate sustained oscillations of a frequency sufiiciently high 5 for radiation power value comparable with that developed by the transmitter 21. These high frequency .oscillations, together with the oscillations -of telephonic frequency, are impressed .upon the input circuit of an amplifier 51 andscrveto produce in the out ut-circuit of this amplifier a modulated "gh frequency wave similar to that developed by the. amplifier 3, as describedand cla'med in the patent to Van der Bijl 1,350,752, patented August 24, 1920.

These modulated high frequency oscillations are subjected to a voltage amplification bvmeans of a plurality of amplifiers of the type of'26, whose 5.6 offaboutl microfarad capacity each. In circuit of the voltage both the amplifier 'ing 58 and condenser 59. .Condenser 59 is shunted by a high resistance 60 and is included in the inputcircuit of the

power amplifiers

27, 28, etc.'

It has been found feasible to heat the filaments-33, '34, etc, from an alternating current source, and, as shown in Fig. 2, the

filaments

33, 34, etc, are heated from a 60 cycle generator 61." Where an alternating current source is employed for this purpose,

the filament circuit should be shunted b an inductance 62,'the-m-iddle point 63 of w ioh by condensers 55 and In the development of the system of Fig.

is connected to the output. circuit through a "ill resistance-64. .Each half of the inductance '62 is shunted by a condenser 65.

in a practical employment of the system herein described in which effective long range communication has been obtained, six voltage amplifiers of the type of 26 were employed, and were supplied with space current from a gener tor 5a of 500 volts output. 1 250 of the amplifiers of the type of 27 and 28 were employed, and were supplied with space current from a direct current generator 66 shunted by a condenser 67 of 100 microfa-rads capacity and deli ering space current at a; voltage of 600. The filament circuit was supplied by a60 cycle generator 61 delivering current at a voltage of 10 volts. The inductance 62 was givena value of .4 milli-henry and the condensers 65 each had a capacity oflOO microfarads.

Although this invention has been described in connection with radio signaling, it is also applicable to'selective transmission of any kind and to high frequency transmission over conducting circuits as well as to radio transmission;

What is claimed is: 1

' l. The'method of signaling which consists in modulating carrier waves of insufficient power for transmission to agdistant station and in increasing the power of said modulated waves before they are transmitted.

2. The method which consists in modulating, in accordance with other waves,

lll

carrier waves of "insufficient power for transmissionto a distant station and in in-; creasing the power of sand modulated waves before they are transmitted, V

' 3. The method which consists in modulating, in accordance with electric current waves, carrier waves of insufficient power for transmission to a distant station and in increasing the power of said modulated waves before they are transmitted.

4. The method which consists in modulating, in accordance with signal currents,

=carrier waves of insufficient power for transmission to a distant station and in increas ing the power of said modulated waves before they are transmitted.

5. The methodiof signaling which conslsts in generating carrierv waves, supplying message impulses of a power value comparable to that of said waves, modulating said waves in accordance with saidiim ulses and in amplifying the power value '0 the modulated waves to a degree sufficient for long distance transmission;

6I In a signaling system, the combination of means for-supplying modulated carrier waves, a conductor ada ted to transmit said waves, and an amp 'fier between said means and said conductor whereby said wavesare amplified beforethey are sent to a distance.

7. In a signaling system, the combination of means for supplying. modulated carrier waves, a conductor adapted to transmit said waves, and a vacuum tube of the audion type between said means and said con-o ductor whereby said waves are amplified before theyare. sent to a distance.

9'. The method of controlling'the emis-' sion of high power, high frequency waves bv means of feeble signal waves which consists in generating feeble high frequency oscillations, modulating said oscillations in their feeble state by means of said feeble signals, and amplifying said feeble modulated oscillations to the high power state in which they are to be transmitted.

10. The method of controlling the emis-' sion of high power, high frequency waves by means of feeble signal waves which consists in generating feeble high frequency oscillay tions, modulatlng sald oscillations .in their feeble state by means of said feeble signals, and separately amplifying the voltage and amperageofsaid feeble modulated oscillations. p

11. The method ofcontrolling the emission 'ofhigh power, high frequency waves by means of feeble signal waves which con sists in generating feeble high frequency oscillations, modulating said oscillations in their feeble state by, means of said feeble signals, amplifying the voltage, and sub sequently amplifying the amperage ofthe modulated oscillations.

12. The method of controlling the emission of high power, high frequency waves by means of feeble signal waves which consists in generating feeble high frequency oscillations, modulating saidoscillations in their feeble state by means of said feeble signals, amplifying said feeble-modulated osclllations into modulated oscillations having a relatively high voltage, and in amplifying said high voltage modulated oscillations intomodulated oscillations having both a relatively high voltage and a relatively high amperage.

13. The method of controlling the e1nission of high power, high frequency waves by means'of,feeble signalwaves which consists [in generating feeble high-frequency oscillations, modulating said oscillations in their feeble state. by meansof said feeble s gnals, and caus ng'said modulated osc1lla tions to vary the potential across the input circuit of asystem of thermionic amplifiers having a-lar'ge power output.

14. The method "of "radio, transmission which-comprises modulating a carrier wave distant station,

" comprises modulating a carrier wave in ac= eordance with speech waves,

increasing the power of said modulated carrier w'ave before transmission, and radiating said wave of increased power.

means for supplying carrier Waves ofin sufiicient power for transmission to a dis-' tant' station, I means for modulating said waves, and means for increasing the power of said modulated Waves before transmission. 1 I

'17, A signal system comprising a source of carrier waves, means for modulating said u Waves in accordance with signals, a carrier cuit of said repeater, ulated oscillations to vary the, potential across the input circuit of a system of'ther wave transmission conductor, and means 7 connecting said modulating means and said conductor for inereaslng the power of said modulated waves.

18. The method of transmitting signals through space which consists in generating oscillations of radio frequency having a power value comparable with that of the signal impulses to be transmitted, impressmg said oscillations together with said impulses on the input circuit of, a thermionic repeater, whereby modulated high frequency oscillations are produced in the output cirand causing said mod? mionie amplifiers having a large power output: a 1 a I '19: In a signaling system, the combination of means for rents,a conductor adapted to transmit said waves, and an amplifier between said means' and said conductor whereby said waves are amplified" before they are sent to 'a dis:.

tance. i

tion otmeans for supplying carrier waves modulated by other waves, a conductor adapted to transmit said Waves, and an. am-' pllfier betweensaid means and sa1dconduc.-'

tor whereby said Waves are amplified before they are s'ent to a distance.

' 21. The combination with means for; gencrating high frequency oscillations and for modulating .sa'id oseillationsin accordance arranged in multiple, fier energized bysaid with low frequency mitted, of a plurality of current amplifiers and-a voltage impliinto said. current amplifiers,

creased;

power 'for transmission to a transmission system comprlsing circuit, a t

"the high power :state supplying carrier waves ;m'odulated'1n accordance w1th signal curimpulses to be trans:

means and working whereby the Power of a d modulatedoscillations s 1n--' erating high bfreqlienc oscillations and for modulating sa'id oscil ations in accordance with" low equency impulses to be "transmitted, of a plurality of thermionic amplifiers'arranged in multiple having a com mon inputcircuit, and a thermionic amplifier adapted to be energized by said means and working into said input circuit, whereby the power of said modulated oscillations is increased. i

23. The combination with means for generating high frequency oscillationsand for modulating saidoscillations in accordance with ,low frequency impulses to be transmitted, of a plurality of thermionic currentamplifiers arranged in multiple havinga common in ,ut circuit and a common output ermionic voltage-amplifier associated with said. means and working into said input 'circuit, whereby the power of said modulated oscillations is increased and an antenna circuit coupled with said output circuit.

24, Thecombination with a thermionic amplifier having an input circuit and an ,output circuit, of means for impressing a frequency electromotive force, and means connected with said output circuit for amplifying said high frequency oscillations to in which they are to be transmitted.

25. In aisystem for radio, transmission, the combination with a thermionic amplifier having an input circuit and an output circuit, of means for impressing an audio frequency electromotive force and a radio'frequency electromotive force of comparable I f; and feebie intensities on said input circuit 20.In a' signaling system, the combin ng whereby a low power modulated high frequency current is produced in said output circuit, and means'for' amplifying said modul'ated current to a high it isto be transmitted.-

26.,In a s the combination with a thermionic repeater having andnput circuit and an output circuit, of means for'iinpressing an audio frequency electromotive force and a radio frequency electromotive force ofcomparable magnitudes on said inputcircuit whereby a modulated high frequency current is produced in said output circuit, and a plurality of thermionid repeaters coupled with said output circuit for amplifying said modulatedfhi h frequencycurrents to a high power Va ue.

power state in which 27. The method 0f carrier current. telephony which includes generating speech waves and carrier current Waves of comparable magnitude, impressing all of said waves upon a modulator, amplifying the modu lated carrier waves and transmitting them to a distant station, said carrier waves be-' fore amplification being too feeble for transmission and reception at said station. a 28. The method of higl frequency transmission which includes generating low frequenc y modulatlng waves and carrier current waves of comparable magnitude, im-

pressing all of said waves upon a modulator, amplifying the modulated carrier waves 15v and transmitting them to a distant station,

said carrier waves before amplification be- .ing too feeble for transmission andreception at sald station.

In witness whereof, We hereunto subscribe 20