US836531A - Means for receiving intelligence communicated by electric waves. - Google Patents

Description

No. 836,531. PATENTED NOV. 20, 1906. G. W. PIOKARD. MEANS FOR RECEIVING INTELLIGENCE COMMUNIOATED BY ELECTRIC WAVES.

APPLICATION FILED AUG.30,1906

GREEN LEAF WHITTIER PICKARD,

, :1? run I STATES AT NT OFFICE.

OF AMESBURY, MASSACHUSETTS.

MEANS FOR RECEIVING INTELLIGENCE COMMUNICA'I'ED BY ELECTRIC WAVES.

Specification of Letters Patent.

Patented Nov. 20, 190;}.

Application filed August 3 0, 1806. Serial No. 332,697-

' close the form of the invention which I now consider to be the best of the various forms in whichfthe principles of the invention may be embodied.

This invention relates to means for receiv- 'ing" intelligence communicated by electric Waves.

The object of the invention is to provide a v "commercially-useful means for operating a:

device for translating the communications into. intelligible form exclusively by the energy of the oscillatory current generated by thereoeipt of the waves.

To this end the object is to practically-util- Q2 ize a combinationxof the phenomena of the generation of heat by electrical ener at a thermo-junction and of the generation of electrical energy by the heat energy at a th'ermo-j unction.

o That these objects have been actually ac complished by this invention has been demv constrated by practical tests, consisting of: fthe' intelligible reception of communication over. longdistances in connection with com-' 3 5 fm'ercially-employed' wireless-telegraphy in- .stallations.

Oi -the drawings, Figure 1 is a diagram} its present most efiicient form, Fig. 3 being a slightly-modified form.

In Fig. 1 thegeneral arrangement is the well-known loop 'form of-.wave-interceptor A k A, o eratively provided zwith the usual 'ad-. justa 1e capacity C, inductance L,adjustable in both the wave-interceptorand oscillation}- receiving circuits, the inductance "L', adjustable in thewave interceptorcircuit, and the connections of the latter circuit to ground at G.- I

rinciples of- In Fi 1 the circuit L,-T J, C, T'i'eceives the osci lations generated in the -wave-intercepting loop, the inductance L be' adjustable in the oscillation-circuit, which is well adapted for use with the thermo-couple de tector, as it includes the adjustable condenser C and the device T in shunt to this condenser. The device T is preferably a telephone-receiver and may be any. other form of device, such as a sensitive galvanom eter, which will indicate an abrupt flow of direct current. The detector should in use be maintained in good electrical connection in the oscillation-circuit, and the thermo-junct1on T J should also be a good electrical contact. The lead to the shunt-connected condenser C and the tele hone T is taken from the lower end of the in uctance L, so that the telephone and its parallelconnected condenser are in series between the detector and a part of the inductance L, which is of lower potential with respect to the ground, the advantage of this arrangement of receiving means being that it obviates the establish ment of a deleterious-local condenser action which would otherwise take lace in the leads to and the windings Lofth'e indicating device if connected in a circuit through the detector.

A furtheradvantage of 'the arrangement is that the proximity to the human body of the 8 5 detector and the lower inductance connection is during the receipt of-the oscillations and with respect to them of the same potential as that cf the earth.

The detector, roughly indicated at T J in Fig. 1, is shown in detailin Fi 2. 1 is a wooden base to which are secure an angular metal su port 2 and a metal plate3, provided with bin mg-posts 415 for the leads of the oscillating circuit of Fig. 1. One element of the detector is the chuck, which is removably screwed into the plate 3 by the part 6. This chuck consists of apiece of metal M, to which is soldered a metallic plating M P, such as cop or or silver, which lating is, deposited' on t e material N in or er to minimze the generation of thermo-electromotive force between the material and the metal M by'p'roviding a large area of surfacecontact between them with respect to the area of the junction T J of Fig. :-1. The depositionmay be by electro lating or by fusing a layer of the material g1 upon a metallic surface, or otherwise, and, asshown in Fig. 3, 1t 1s sufiicient to place the material N ina liquefied mass of fusible metal F Mina chuck-cup 18, provided with a screw 17, so that when the metal F M cools and solidifies the materlal N will be firmly embedded in andin good electrical contact with the metal F M.

- The operative thermior-junction (TJ oi' Fig. 1) is located atrthe'lower end ofthe hol'low- W metallic sleeve 7 of {F1 2,;which junctionis of less surface areawit the material N than at the surface MP. This sleeve slides along.

the metallic roj eotion 8, .diepending from the metallic ball 9, the ball forming-a ball-and--' socket universal joint with the part 110, of thin metal, which is stamped to shape and -se-' cured tothe metallic support 2 so as t6 com- 'plete the circuit.

The sleeve member 7 of the thermo-'u.nction may be-of any suitable metal whic is a. good conductor of electricity. The other: member N of the thermo-junction shouldhave a high thermo-el'ectromotive force and ahigh electrical resistance iniorder to-concentrateas much as-possible of the energyof the received osoillations in the form of Joulean heat, at the point at which the'heat energy is converted into an electric current by reason-of the difierent physical characteristics of the two elements forming the thermocouple. The member N should havea thermo-electromotive-force in order to obtainthe maximum percentageof regenerated seriousopposition. to the electromotive forces setup by the-received oscillations,and' there by prevent the flow of the-feeble oscillatory currents whichif not so-opposed operatively heatthe thermo junction, to generate a thermo-electromotive force to cause the-loud clear click in the telephone. a

The member'7 of the thermo-couple is me tallic; but the best results so far have been had with the member Not a non-metallicnaturalelement, such as silicon, which possesses in a high degree the desired properties of high electrical resistance and high thermo-electromotive-force. It appears to be most useful either in the massive amorphous or graphitic solid form. This material may be used commercially when pressed into good electrical contact between two good conductors, such as-c"opper, irrespective of the apparent relaasatsi tivesurface areas; but thisiisnoitijthe most I oscillations will cause the same temperature rise in each junction, and consequently the. same thermo-electromotive force-will lie-gen- Lunction by connecting the -erated at each-junction,-but of opposite signs, resulting -m a complete annulment of any useful action.

simple material etween two conductors in the circuit, and

1. However, by providing a relatively very large area of surface contact at thej-unction which it is desired to'make of lower resistance, as --by the metal plating or embedding in Figs. 2 and 3, it is possible to obtain nearly "all thethermo electromotive force as of one sign, and this is the preferredembodiment of the invention. 5

In .order to obtain the best results, the

above specification should be carefully fol lowed. In such case the operation is wholly as follows: The energy of the received oscillationsis converted into heat-atthe high-resistthermo-electromotive force with the low resistance or metallic element, the amount of heat and consequent temperature rise being proportional to the square of the-current and the resistance, according to the well-known law of Joule. This heat energy is then, ace cording to this invention, regenerated or converted into a direct electric current. So far I have been able to convert upward-of ten per cent. of the energy of the oscillations into direct-current energy. The device is therefore an. electrical converter orrectifier, and inasmuch as the potential of theregenerated direct current isdifierent from thatof .the oscillations. it is an electrical trans" vigor, as is indicated by'the fact that the only energy employed to commercially operate hence the amount of heat generated will always'be so much greater at one junction that there Will exist-a suflicient preponderance of thermo-electromotiveforce of one sign toop- ,erate the sensitive indicating device T of Fig.

-ance junction of the element having high TIC the telephone T is that of the received oscillations. bereduced to a minimum} because, so-far as it maybe permitted to exist, it is in the direction of an increase-which involves areducztion in the heat generated and a consequent reduction in the generated thermo-electrc- All resistance-varying action should Tr:

' tions u on the telephonet motive force and the useful effect of the latter upon the telephone. If any resistance-varying action be present in any embodiment of the invention, it will, however, have no other effect except to decrease the useful thermoelectric actlon, because it cannot alone operate an indicating device and because no auxiliary source of electromotive force can be used which it might vary to operate the telephone. Trials have demonstrated that the use of an auxiliary source of electromotive force with this detector results in an annulment of all effect of the energy of the oscillaat is, an annulment 0 the thermo-electric action-and that any resistance variation which might take place was ino erative, as to the auxiliary source, to pro uce'an indication in the telephone.

The remarkable fact that the telephone can be o erated in a commercial manner solel by t e converted energy of the received oscil ations is explained by the statement that that feeble energy which is received at the ordinary commercial wireless-telegraph station is amply sufficient to'operate a sensitive receiving instrument, provided that the translation of this energy into the form of a direct current is efficiently accomplished. It is of course necessary in commercial work to effect'this conversion, because there is no known indicatin means which can be sensibly affected by t 1e received energy of commercial long-distance wireless telegraphy when in the form of high-frequency oscillations, notwithstanding the fact that a sensitive tele hone ma as an experimental feat,

' be slight y afi'ecte bythe oscillations emitted thousandth of an erg per dot.

from a near-by or very powerful sending station.

The energy required to com n'iercially o erate a telephone'that is, to produce in it a 0 earlydefined dot, in, for example the Morse code is approximately one millionth (1 X 10 erg. The energy received by the average long-distance commercial Wireless-tele raph station is of the order of magnitude of one- The efliciency of the a paratus of this invention, as demonstrated y trial under commercial conditions,

- is upward of ten per cent. There is thus ample margin for commercialo erativeness for the least sensitive form of t iis invention in the case of the present longest-distance wireless telegraphy.

The speed of reception with this invention is unlimited, since it is not only self-restoring to its sensitve state, but this restoration is practically instantaneous, because the small quantit of heat which is generated by the receive oscillations comprising a signal is rapidly conducted away, partly by thermal conduction, to the metal ortion of the couple and the remainder by t e regeneration into an electric current, which finally expends its energy in the indicating device.

The advantages of the new detector are as follows: It fulfils all requirements of commercial Wireless telegraphy as to sensitiveness, speed,stability, and freedom from delicate adjustments. I have found that the continued sensitiveness of the detector is in no Wise impaired by severe static discharges. It is also simple and cheap in construction. It is not affected by changes in atmospheric tem erature or humidity. Its sensitiveness so far as not been impaired by continuous and continued use. It has no limited number of operative contact-points, as in the case of crystalline masses, which operate by the variatlon of resistance due to a heating of a small art of the masses. Any portion of an one o the classes of material havim high t iermo-electromotive force and high edectrical resistance, included within this invention, makes an op erative thermo-junction with a metallic conductor if held in good electrical contact-therewith. This invention requires no auxiliary source of heat, as has been necessary with previous converters designed for high-frequency oscillations.

It is an important, practical, as well as economical advantage of this invention that it essentially dispenses with auxiliary sources of energy in that such sources, such as batteries and the requisite accompanying poten tiometers, are expensive in initial cost and In maintenance for operation and repairs and require frequent replacement. There is apparently no limit to the operative life of the detectors included in this invention.

As an element of a means for receiving intelligence communicated by electric waves, the substance silicon, substantially as and for the purpose described.

GREENLEAF WHITTIER PICKARD.

Witnesses: r

SAMUEL HUBBARD MANSFIELD, HENRY AZOR WENTWORTH.

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