US827523A - Wireless-telegraph system. - Google Patents

Description

No-827,523. Y PATENIED JULY 31, 1906.

E L. DE EOEEST.

WIRELESS TELEGRAPH SYSTEM.

APPLICATION FIL ED DEO.6. 1905.

3 SHEETSSHEET 1.

No. 827,523. PATENTEDJULY 31, 1906.

- L. DE FOREST.

WIRELESS TELEGRAPH SYSTEM.

APPLICATION FILED DEO.6; 1905 s SHEETSSHEET 2.

\A/PFHESEEE:

N0. 827,523. PATENTED JULY 31, 1906.

L. DE FOREST.

WIRELESS TELEGRAPH SYSTEM.

APPLICATION FILED 1350.6,1905.

3 SHEETS-SHEET 3.

UNITED STATES LEE on FOREST, OF'NEW YORK, NY.

WIRELESS-TELEGRAPH SYSTEM.

Specification of Letters Patent.

Patented; Julyifi, 1906 Application filed December 6,1905. Serial No. 290,567.

' To a It'll/717% it may concern:

. tion.

. the receiving operator at said station is 'en-,

- My invention relates td Wireless telegraphy and has for its object a systemwhich is provided with separate transmitting and receiving antennae at the same terminal station and which thereby has the advantage that abled to cut in upon and interrupt the transmitting operator at another station, as well as certain other advantages hereinaftei" set forth. f I

In the drawings which .accornp'a'ny and form apart of this "specification and which illustrate diagrammatically several systems i of circuits whereby my invention may be carried into effect, Figure 1 represents a transmitting and receiving system and Figs. 2, 3 and 4 represent receiving systems and a portion of their accompanying transmitting apparatus.

I shall first describe the system shown in Fig. 1 inwhich the transmitting and receiving sets are provided with separate antennae and shall then show by reference to Figs. 2, 3 and 4 how such constructionenables a receiving operator tointerrupt the transmis sion from a distant station.

In Fig. 1, X represents the building in which the sending and receiving instruments are located and M represents a mast, tower, or other suitable support for the antennae. The sending-antenna A is insulated at its upper end by the insulators D and is secured by the members I and J to the spar B which in turn is secured to the mast. The receiv ing-antenna A is not insulated at its upper end being conductively connected to the rod J of conducting material which by me ans of the cable G passing over the pulley F is sup ported at any desired height by the mast.

'The cable G is secured to the cleat H when n the antenna A has been hauled up to the desired height and the lower end of said cable is connected to earth at E.

It is preferred to give the two'a ntennae dif ferent shapes and for this purpose the conductors of the antenna A are separated by the spreader K a distance about ten feet apart-while those of antenna A are sepatwenty-five .feet apart.

and the insulator n.

rated the spreader K a distance of about spreaders K, K are equal in length and many more conductors are employed in the transmitting-antenna than in: the receiving-antenna. the guys V, V, in the usual manner.

Preferably the.

The spreaders are guyed by When the circuit of the generator A is I closed by the key 70 the high-potential, lowfrequency current developed in the secondary ofthe transformer Q charges the con denser C and said condenser discharges across the gap S therebyproducing highpotential, high-frequency oscillations in the oscillation circuit C S c which, by means of theifisul'amr N and passes out to the earth connection E through the insulator a. The'ratio of transformation, as well as the periods of the oscillation-circuit and the antenna, may be varied by the adjustable contacts c and c, and preferably said periods are made equal.

A certain number of the wires of the rethe auto-transformer L, are conveyedsto the antenna A'Which enters the station through ceiving-antenna, herein shown as the two wires 1, 1, enter the station through one of 'the'insulators N and the rest of'the wires of said antenna enter through the other insulator N, and each set of wires tl'len passes to earth at E through the induetances L, L

By means of the variable contacts (1, d, the desired amount of inductance may be included in the two sides 1, 1, and 2, 2, of the loop antenna A, so that the period of the latter may be madeequal to that of the. tuned receiving-circuit d R C which includes the receiver R, the variable condenser C and a portion of'the -inductance L, and so that said period may be made equal to that of the electromagnetic waves to bereceived. The local circuit which is connected across the terminals of the receiver R includes the head telephone T and potentiometer P which regulates the potential of the battery B to be impressed upon said receiver.

O is a switch for connecting the two sides 1, 1, and 2, 2, of the loop antenna A to the receiving apparatus during the receipt of messages and for disconnecting said antenna from said apparatus during the transmission of messages.

It is not new in wireless telegraphy to employ a switch for the purpose of connecting an antenna alternately -to the transmitting and the receiving apparatus at a station, but so far as I am aware no system heretofore has; been devised in which separate transmitting and receiving antennae are provided at the samestation and in which a switch is employed as above set forth. Some of the advantages of this construction are that it permits the employment for transmitting and receiving of the kind of antennae required,

difference between the point of attachment, I

of the switch to the antenna and the earth from rupturing the dielectric intervening be-- tween the switch and the receiving apparatus. In some of the commercial wirelesstelegraph stations of my construction, I have been able to draw a spark one foot inlength from the transmitting-antenna, and in such case it will be obvious that in order to make use of the same antenna for transmitting and receiving a switch for alternately connecting said antenna to the transmitting and receiving apparatus would have to be over one foot in length and to have a throw of over one foot. However, when a separate antenna is used for receiving, a small, low-potential switch may be used to disconnect the receiving apparatus'during transmission because but relatively small potentials are developed in such receiving-antenna by the oscillations created in the transmitting-antenna at the same station. In some of my stations constructed as shown in Fig. 1, the difference of potential between the pointsio, 0, and the earth during the operation ofthe transmitting system is so small as to produce a spark of only one and one-half inches in length,

and hence it will be seen that the switch 0 need have a throw of but little longer than one and one-half inches.

Another advantage incidental to separate transmitting and receiving antennae is that thereby the receiving-operator is enabled to cut into and interrupt the transmission from a distant station, and various means for accomplishing this result are shown in Figs. 2,

.3 and 4. r

In Fig. 2, a portion only of the transmittin -antenna and of the transmitting-circuits is s own, but it is to be understood that said antenna and circuits are arranged as shown in Fig. 1, and also that in Fi s. 3 and 4, in each of which a portion only of the transmitl ting-circuits is shown, said circuits also are arranged as shown in Fig. 1. At points above the connections d, d, of the antennawiresl, 2, with the inductances L, L, two conductors. connect said antenna-wires to two-pointed terminals of the anchor sparkgaps each about one sixty-fourth inch long, and the third pointed terminal of said gap is grounded at E. A similar anchor spark-gap s has two of its members connected in shunt to that portion of the inductance I) which is included in the tuned receiving-circuit and the third member of said gap 1s grounded at 6. It will now be obvious that as the oscillations created in thereceiving-antenna by the transmitting-antenna A are of sufficient potential to bridge the gaps in the anchor sparkgap 8 such oscillations will pass to earth by way of'sai'd gap andwill not therefore affect While the gap 8 is generally sufficient, it may, as an extra precaution, sometimes be desirable to employ the gap 8, which, in case any appreciable difference of potential exists the oscillations creating said potential to earth at e.

While, with receivers of certain types it would be possible to transmit signals from the transmitting side of the system (shown in Fig. 2) without affecting the receiver R when the anchor spark-gaps s ands are connected as shown, nevertheless with other and more sensitive receivers it is necessary to adopt a still further protection. Such protection is key closes the circuit of the generator A and primary of the transformer Q, and such shuntin may be effected by connecting one termina of the shunt to the outer end of said with the other terminal f of the shunt when the key closes the generator-circuit at g. It will be noted that the anchor spark-gaps do not interfere with the reception of signals from a transmitting-station because the potentials developed in. the "receiving-antenna are far too feebleto bridge said gaps, and hence, when the key is in such position that the shunt around the receiver R is open, any signals which may be sent out from a distant station may be read by the operator at the station shown in Fig. 2, who keepsthe telephone T in position while sending.

It Will be noted that when the shunt around the receiver R is closed at f, the battery B is practically short-circuited, and, inasmuch as the said shunt is closed from six hundred to one thousand times a minute in commercial signaling, the battery soon runs down. In order to remedy this defect, the circuits may be arranged so that the key will open thebattery-circuit as well as shunt the receiver. One arrangement whereby this result maybe the tuned receiving-circuit or the receiver R.-

afforded by shunting the receiver when the.

key and causing said outer end to contact gap 8, which consists of three or more spark- -across the terminals of the 0011 L. conducts 'efiected is shown in Fig. 3 in which for the purpose oi'illustration the receiver is shown connected in series with the antenna A and not in a tuned receiving-circuit as in Figs. 1 and An anchor spark-gap 8, connected to the antenna at point above the receiver and to earth at e, performs the same function as the gap 8 of Fig. 2 performs with respect to the loop antenna shown in Fig. 2. It will be obvious that as the key k of Fig. 3 is depressed, the double-pointed contact Z, which normally is held in contact with the spring h by the retractile spring j, is moved out of contact with h, thereby opening the circuit of the battery B, and immediately afterward is brought into contact with the spring i, thereby closing the shunt around the receiver R. Another way of protecting the receiver during transmission and at the same time preventing the batteryfrom running down by opening its circuit, is shown in Fig. 4, in which one terminal on of the receiver R is attached to the insulating member 1) which projects from the end of the key, so that when the key closes the contact 9, the member m is moved out of contact .With the electrolyte in which its lower end normally is immersed. of vibration of the member p during the operation of the key in commercial working, the member m ofthe receiver is subject to a certain amount of wear, so that I prefer an arrangement,- such as that shown inFig. 3, in which the members of the receiver are not subject to motion.

It is not necessary that the separate transmitting and receiving antennae at a station should be supported by the same mast for it will be obvious that'ea'ch antenna maybe provided with a mast and that said masts may be separated by suflicient distance to permit of duplex working. For example, the transmitting and receiving antennae of a sta-' tion may be separated by a substantial distance of, say, ten miles, which separation will make it possible for the receiving apparatus to receive signals transmitted from a distant system by waves of one wave length or frequency at the sametime that the transmitting apparatus of said station is transmittingsignals by waves of different wave length or frequency. In such case the transmitting and receiving apparatus of the station may be connected y a pony telegraph-line so that the receiving operator can inform the [sending operator by wire telegraph just what he is receiving.

I do not limit myself to the specific apparatus and circuits which I have herein described for the purpose of more fully explain- However, in view of the rapidity I claim 1. In a wireless-telegraph system, the combination with transmitting and receiving systems at a terminal station, of separate multiple antennae forsaid transmitting and receiving systems, .the transmitting multiple antenna comprising a larger number of conductors than the receiving multiple antenna ,spaced than those of the receiving-anteima, and means attuning said transmitting and receiving antennae to different frequencies.

2. In a wireless-telegraph system, the combination with transmitting and receiving s ystems at a terminal station, of separate multiple antennae for said transmitting and receiving systems, the transmitting multiple antenna comprising a larger number of con ductors than the receiving multiple antenna.

3. In a wireless-telegraph system, a receiving-antenna, a receiver associated therewith,

' and means associated with said antenna for protecting said receiver from the effects of excessive electrical potentials.

. 4. In a wireless-telegraph system, a receiving-antenna, a receiver associated therewith, and an anchor spark gap so connected with said antenna as to protect said recei er from the effects ofexcessive potentials.

5. In a wireless-telegraph system, a receiving-antenna, a tuned receiving-circuit associated therewith, a receiver connected in series with said tuned receiving-circuit, means associated with said antenna for protecting said receiver from the effects of excessive potentials and other means associated with said tuned receiving-circuit for protecting said receiver from theei'l'ec'ts of excessive potentials.

6. In a wireless-telegraph system, a transmitting system including a transmittingantenna, a receiving system including a receiving-antenna and a receiver, a transn'iittingkey associated with both systems, and means operated by said key for closing a circuit around said receiver to protect the latter from the electrical efl'ects developed in said receiving-antenna by the oscillations created in said transmitting-antenna.

' 7. In a wireless-telegraph system, a receiver, a battery associated therewith, a transmitting-key and means for closing a circuit around said .receiver and opening the circuit of said battery'by the operation of said key. I

8. Inawirelesstelegraph system, a transmitting system including a transmitting-antenna, a receiving system including a receiving-antenna and a receiver, a transmitting-- key associated with both systems, and means associated with said key for protecting said receiver from the electrical eflects developed in said receiving-antenna by the oscillations created in said transmittingantenna.

9. In a wireless-telegraph systein, a receivand having its conductors more closely' ing-antenna, a tuned receiving-circuit associated therewith, a receiver connected inse ries with said tuned receivin'g circuit, a spark.

gap shuntedaround said receiving-circuit ceiver from the effects of excessivepotentials.

and connected to earth, and a spark-gap connected in shunt to said receiverand so constructedand arranged asto protect said re- 10.1111 a wireless-telegraph system, a receiver, a spark-gap consistin of at least three pointed electrodes connect receiver and aconnection to. earth for one o said pointed electrodes.

11. In a wireless-telegraph system, a receiver, a spark-gap connected in shunt thereto, a transmitting-key and means for closing a circuit around said receiver by the opera- I tion of said key,

. 12. In a wireless-telegraph:system a receiving-antenna,' a receiver associated therewith, an, anchor spark-gap so connectednto said antenna as to protectsaid receiver from the effects of excessive potentials, a transmitting key and means'for further protecting said receiver by the operation of said key. a

13. In a wireless-telegraph system,-a rein shunt to said -with' said'receiver'for protecting said receiver from the effects of excessive potentials, a transmitting-key, and means for further protecting said receiver by the operation of said key.

14. In a wireless-telegraphvsystem, areceiv-ing-antenna, a receiver associated therewith, means associated withsaidantenna for protecting said reeeiverfrom the efiects of- -.excess1ve potentials, other meansassociated with said receiverfor protecting said receiver from the eflects-of excessive potentials,a transmittin key, and means for closing a-circuit 'aroun said receiver by the operation of said .key.

. In testimony whereof 'I havehereunto subscribed my name-this 29th'day of November,

1905; LEE DE "FOREST.

Witnesses: I

. PHILIP FARNSWORTH,

A. E. PARKER.

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