US1522357A

US1522357A - cuement

Info

Publication number: US1522357A
Authority: US
Publication date: 1925-01-06
Anticipated expiration: 1942-01-06
Also published as: USRE16231E; USRE17847E

Description

E. E. CLEMENT if j* aAnIoPHoNE ss'rnn Original Filed Aug. 14, 1922 e sheets-sheet 1 ffW-fl l "l l i 'Aren/z5 ZZ a/ 3 :wrm

l .fm me ro/v Jan. 5, 1925 1,522,357

. E. CLEMENT BADIOPHONE SYSTEM A f-y/ j z Filedl Aug. 14. 1922 e {sheets-snag.: 2.

Iam 6, 1925.

E, E. CLEMENT RADIOPHONE SYSTEM.

Original Filed Aug. 14, 1922 6 Sheets-Sheet 4 nac!! Jan. 6, 9253.

E. E. CLEMENT #mot-'Hwa sysai! 6 Sheets-Sheet E Y B J| |v .m @Nu l Jan. 6, 1925.

E. E. CLEMENT RADIOPHONE SYSTEM Original Filed Aug. 14',

1922 6 Sheets-Sheet 6 O O O O O rNM Patented Jan. 6, 1925.

UNITED sTAT'Es PATENT OFFICE.

EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOB TO EDWARD F. COLLADAY, O'F WASHINGTON, DISTRICT OF COLUMBIA.

RADIOPHONE SYSTEM.

Application led August 14, 1522, Serial No. 581,829. Renewed July 22, 1924.

To all whom it may concern:

Be it known that I, EDWARD E. CLEMENT, a citizenof the United States, residing at Washington, in the District of Columbia, have invented certain new and useful Improvements in Radiophone Systems, of which the following is a specification, reference being had therein to the accompanying drawing.

My invention relates to systems of communication, and particularly to telephone and radio systems.

Itha's for its objects, among others, the following: To organize radio broadcasting Yservice on a commercial basis, and to control the service units or receiving stations so thatthe various contingencies incidental to commercial operation may be eliciently met, such as maintenance, supervision, and the imposition and collection of charges; to localize each unit of a system, so that it may v be tested and supervised; to standardize the distributed unit agencies in a system, while enabling them to receive messages broad- 4 caste-tl on various wave lengths; to control radio broadcasting so that it may supplement in organized service existing telephone exchange systems n such manner that the Government, in time of public need, may take over such radio broadcasting systems on an organized basis, and operate or supervise the same, without disturbance of the telephone service.

Incidental objects are to enable transition from wired to so-called wireless methods of communication to be accomplished without substantial changes in pract1ce, or injury to investment; and to ensure the proper and natural organization of radio systems when such trans1t1on occurs.

The foregoing objects are attained by the` s localized areas, of standardized receiving instruments. each local area taking its broadcasting service from its own central station .on such wave. length as ma)Y be fixed and determined for that area. Each receiving station is connected to the local central station by a wire circuit, through which both distribution and the control of the local station are attained. Without being subjectto the limitations of an all-wire telephone system, this arrangement enables me conveniently to feed the substations with current from central for divers purposes, to control the receiving instruments at said stations from the central station, and to meter the radio service rendered for the purpose of making charges. Other benefits flowing from this arrang ment will suiiciently appear from the detailed description hereinafter.

In order to make it possible for subscribers to both send and receive, without technical knowledge and without. the necessity for operators' licenses. I provide. the substation radiophone instrument with means for communicating over the wire circuits to the radio central station, where the. may be. connected through suitable amplifiers to broadcasting wave transmitters. This attains another object, that is to sav. it gives the radio operator supervision and control of the message to be broadcasted as it comes over the telephone circuit. and be.- fore it goes on the wave transmitter.

The use of individual wire circuits as described, renders it possible to locate each unit and by special means which will be described` to test and supervise said unit at the substation, as well as to disconnect and disable theslime in case of necessity.

B v using standardized receiving units. all uniformly tuned to the wave length of the local distributing station. I am able to provide said distributing station with sensitive and powerful receiving and relaying apparatus and circuits, whereby distant stations muy he picked up. and various wave lengths muy be .received by variable tuning and their modulations relayed on the standard local wave length to the subscrilxrs. who can receive and recognize the original messages thus relayed. without the necessity of variable tuning or highly sensitive instrtunents at their stations. With the above arrangement for distribution, by which the ultimate receiving instru-ments are reduced to the simplest form compatible with their purpose. I .am enabled to concentrate apparatus requiring more elaboration and careful adjustment at the central stations. These are so related to existing high power broadcasting stations,

and to others equipped as a part of the system, that uniform service and uniform programs may be distributed to the local central station according to a regular schedule, and the cost of the primary broadcasting, as well as any special programs put on by the local distributing stations, and the operation of the same will be borne by the subscribers by way of ultimate distribution in individual charges against them.

To control the radio communication in order that it ma supplement existing wire agencies, I combine the above described radiophone system with a standard telephone exchange system, locating the standardized radiophone instruments at the telephone subscribers stations, making their wire circuits the existing wire circuits of the telephone system,'providin means whereby the use of the radiophone side of the system may be carried on to the fullest extent without interferin with the telephone side of the system, and without changing any of its circuits or apparatus. The telephone service is iven precedence, so that whenever a subscri er is calling or called over his telephone line, all radio connections which might interfere are temporarily broken. From the telephone standpoint, the radiophone instruments may be regarded as extension telephones su erimposed on the telephone lines at the su scribers stations, and in a larger as ect the radiophone system as a whole may e regarded as a phantom duplication of the te ephone exchange system upon which it is superimposed. It is intended that the two shall be controlled and operated by the same company, and since telephone circuits are usually idle more than 90 per cent of the time, an opportunity is thus afforded to increase the earnings of the existing physical equipment, as well as to produce substantial earnings on the additional investment required to install the radiophone instruments and switchboards.

This device for controlling and directing the radiophone service over existing lines renders it of organized telephone exchange systems, ossible for the Government, in case of nee to take over the radio systems of the country as an organized unit, under trained expert management, and to superrise all transmission thereover without any interference with the general telephone service. and if necessary, without the knowledge of the subscribers thereto.

It will be apparent after reading the foregoing statement, that my incidental objects are attained as a necessary result of the general organization and arrangement described. The amount of capital invested and to be invested in telephone exchange systems in order to meet. the demands of service is rapidly increasing, and it is not only highly desirable to increase the earning capacity of the physical telephone plant without a corresponding increase in the investment, but it is also necessary to forestall independent development of disorganized radio communication systems as well as their illicit or disorderly use.

With the foregoing arrangement, the management of and responsibility for the great bulk of the radio apparatus in the country will be placed in responsible hands organized and trained to exercise it eiliciently according to law. For the detection of crime, for the general dissemination of intelligence, and to meet emergencies, including the national emergency ol war, it is indispensable that such an orderly arrange ment be brought about as will regulate the distribution and control of the apparatus, and the systematizing of the radio service on such a basis that it will pay for itself.

No claim is made herein to the method of broadcast distribution disclosed as such, nor to the method of control of the substation radio hone apparatus from central, the same eing claimed in a separate eopending application, Serial No. 755,574, filed December 12, 1924.

My invention is illustrated in the accompanying drawings in which:

Fig. 1 is a diagram showing a general system embodying the same;

Fig. 2 is a diagram showing a central station telephone switchboard, subscribers lines terminating thereon, and subscribers telephones connected thereto;

Fig. 3 is a diagram to be read in connection with Fig. 2, showing the r-.idiophone set at one of the subscribers stations, and the radio switchboard and associated equipment at the central station;

Fig. 4 is a diagram showing a substation battery charged and controlled over a phantom circuit imposed on a metallic magneto telephone circuit;

Figs. 5,*6, 7 and 8 are schematic circuits showing methods otl connecting the radio battery with relation to the centralized telephone battery: and

Fig. 9 is a diagram of a modified arrangement of circuits.

Referring to Fig. 1. 1. 2 and 3 represent telephone subscribers stations connected by wires 4. 5 and 6 to the central telephone exchange T, constituting the distributing center for the area in which local subscribers 1. 2. 3. etc.. are located. Superposed upon this telephone system is a radiophone system comprising a central station 8 and subscribers stations 1. 2, 3*. ete. The central radio station or exchange is provided with switchboards and a complete broadcasting equipment. and the subscribers` stations l". 2". 3. etc., are provided with receiving instruments all standardized for the same wave length, and adapted to relan Iii)

spond to the waves radiated from the central station S. The. interrelation between the telephone system and the radiophone system is by means of physical connections indicated at 1*. 2* and 3b at the subscribers stations. and multiples or trunk extensions from the telephone exchange switch boards to the radiophone exchange switchboard in station No. 8. The detail of these connections will appear hereinafter, but it should be stated here that the system of connections is such that telephone wired traie has the right of way over the wires, while the radio trailic has the right of way over the radio side of the system. The arrangement is such that the radio operator cannot interfere with telephone operation, nor can a telephone operator interfere with the radio operation, although under proper conditions each can act freely by way of borrowing facilities from the other. At all times. should a question of precedence arise, the apparatus is arran ed so as automatically to cut o' the ra 'o connections and to leave the wired lines clear for telephonie use.

Stations

12, 13 and 14 in this figure are typical of indiierently located distant sta tions which may or may not be a part of this particular system. As the figure is typical only, no attempt has been made to give the geographical location of such sta tions or to show the actual arrangement and distribution ofthe telephone centers through which iinal broadcasting to the subscribers must take place. The main purpose of this figure is to crystallize the method employed. by which the development of a very large lnumber of unrelated individual receiving stations is replaced by an orderly system of distribution through the telephone centers, whereby the individual receiving instruments are localized. maintained, controlled. and supplied with definite service through regular channels, for which a definite charge can be made and collected in the manner usual in wired systems of communication. lnasm-.ach as the number of Wave lengths available for transmission is limited in the to such stations as those indicated at 12, 13

and 14. as well primary stations maintained and operated by or under the direction ot' the telephone organization itselt'. Il v means understood in the art. messaffes rcteived at the radio central stations are reis made for keeping the telephone lines and central office circuits clear of all grounds or other disturbing connections during conversation. When the radiophone go s into servv ice, by closing the filament switc its operation in receiving is identical with that of any radio receiver. and in the event that use is made of any partial transmission of waves over the line wires, as will be hereinafter pointed out, said waves will be at a frequency above or below the limits of audition. In the present diagram, Figs. 2 to 9 inclusive, l have shown the-circuits arranged with nothing but continuous current for radio purposes over the telephone line wires. This is the simplest form of control and the one nearest to present-day telephone practice. and is absolutely certain not to produce any disturbance in adjacent conductors in the telephone cables. Each radiophone set is provided with a cut off relay energized when the telephone set goes into commission. either by calling or beingr called, and at the central oce whenever the radio operator takes control ot the line. he disables it in the usual manner by pulling up thc cur. ot'f relay at the telephone switchboard. this however being subject to the condition that a special tone test may be put on. so that all operators may know that the line is held on the radio board.I and subject to interrupt-ion for telephone connection. I prefer to use this tone test. onl v with the radio operators testing plug. because his regular connecting plm.r inf-Hides within its functions that of connecting a subscriber through the station amplifier to the broadcasting transmitting set. and a connection of this character .should not be interrupted without permission.

Referring now to the diagrams.I Fig. 2, A and A are two subscribers stations connected by line. wires 16-17 and 18-19 respectivelx tothe central station C where they terminate on jacks .l and J. P--P are plugs forming the, terminals of a cord circuit itl-Q1. 2:2--L3, having a bridged repeating coil I. ringing and listening keys K and K', supervisory signals 8-8 and bridging connection to the main battery B. The same battery is shown supplying current to the line relays L. L. and through contat-if; :1t the cut oli' relays L. L3 to the. respective lines for callin.;r purposes. In this system, when a subscriber takes down.

his receiver, the line relay lights its lamp, which is extinguished when the operator inserts the answeringr plug. Battery suppl)7 for the connected lines is thereafter taken through the cord circuit 20-22, 21-23, in a manner .well understood in the art. lVhen the substation telephones are out of service, with their receivers hanging on their hooks, the line circuits are conductively open for direct current, leaving the ringers Q and Q. in circ-uit for alternating ringing current passing through the condensers g.

Referring now to Fig. 3 it will be observed that. the radio switchboard which I have designated generally by the letter R, is connected to the subscribers lines by multiple taps marked 16. and 17, and 1", and 18, 19, 19". These terminate on multiple jacks J2, J3, corresponding to the multiple jacks on the telephone switch-l board. It should be noted that throughout this system the tip wires 16 and 18 with their branches are connected to ground, while the sleeve wires 17 and 19 and their branches. are connected to battery. This is extended into the radio side of the. system for the purpose of securing proper balance between the main battery or power plant of that side and the main battery or power plant ot the telephone side of the system.

At the subscribers stations taps are also taken ott' from the telephone terminals to the radiophone terminals as indicated at 18, 19, and 19". (The. radiophone is shown only at one substation for sake of simplicity oi illustration.) The two branches 19c and 19 are taken from the sleeve or battery side of the line 19. and are connected to opposite terminals of the winding of a relay L, which constitutes the substation cut ofi' relay for the radio hone. The winding of this relay is bridge by a. condenser q2 through which both ringing and voice currents can pass without su stantial impedance. lVhere the radiophone is attached to a party line substation, this relay L* may be omitted. since on such party lines there are usually grounds on one side or the other. As will presently appear, the radio circuits described herein are applicable to two-party or four-party lines, with individual metering of the party stations.

Norn'ially. that is to say when the telephone. circuit is not in use, the cut ot'f relay L* is deenergized and as a consequence the wire 19 is connected through a back contat-t of the relay through extension wire 24 to the branch .25 connected to the A battery marked A, in Fig. 3. The wire 18 similarly passes through a back contact of the relay to the extension wire '26 leading to test or listening relay 27 and ground. 18, it will be, remembered, leads to the tip or ground side of the line, therefore it is the side which in the radiophone can be made. use of with a permanent ground or grounds, without disturbing the balance of the telephone circuit.

The radiophone receive' at the substation A is shown as comprising an antenna 22S, tuned coupler :29, detector tube 30, audio amplifier tubes 31 and 32, and the

usual transformers

33, 34, 35, the last mentioned transmitting the amplified audio waves to the. telephone receiver or loud speaker 36.

he ifilament battery is A? The plate battery is B, and suitable tuning condc-nsers and coils, ticklcr coil for regenerative effee-ts. etc., are provided as required. I should remark in passing that this representation of the radio receiver is intended to be typical only. The present invention does not concern itself specifically with the design ofthe local radiophone sets, and other circuits and apparatus may be substituted for those shown in the diagrams without departure from the invention.

The relay L5 has four pairs of contacts. one pair 27 closing the wires 25 and 3T from battery A, to the filaments. The second pair 27h closes the

wires

25 and 38 so as to put battery A, on the radiophone transmitter T', and through the induction coil I. to ground. The third and fourth pairs of contacts 12T, '27, close the wires 39 and 40. forming terminals of the secondary induction coil circuit I', to the tip and sleeve side of the telephone line respectively, through the back contacts of relay L. The transmitter T is shown hanging upon a hook switch H controlling the connection of wires 4l and 42. constituting a parallel link between the battery A, and the tilanicntbus-ll. Thus the filament can be heated and the radiophone put in service either through the agency of the relay L, or by the switch hook H. The former is controlled by the radio operator at central, and the latter by the subscriber at the substation. In addition to the hook. the subscriber has a manual switch /z by which he can connect the battcry wire. 42 through a wire 44 to his transmitter T, coil and ground, so as to energize his talking circuit. I provide an ordinary telephone receiver I" in series with the secondary of the induction coil I. and I interpose a pair of condensers g, if between the secondary of the induction coil I and the. receiver f on the one hand. and the terminals of relay L5 on the other. so that while the subscriber by means of switch h can connect his phone '1"-f for receiving calls over the telephone line. he cannot originate calls` thereorer from the radiophone extension.

Returning non to the central station. and particularly to the radio department thereof shown in Fig. 3. T represents a broadcasting transmitter, symbolized in very simple form. but supposed to contain theusual elements ot power supply. modulator, oscillator and aerial, with suitable a1npliication ot the audio waves supplied on the input side. The jack connected to the amplifier t2 and thence to the transmitter T, symbolizes a group of such jacks or equivalent connecting means such as automatic switches. controlled by dials or keys for connecting any of the wire lines to said radio transmitter. Detailed appliances. both for the switching and for the radio transmission. are well known in the art, and need no specific description in this specification, my present invention having to do particularly with the method of transmitting by wave radiation to the substations, and of bringing in all conversation originating or received at the substation radiophone over the subscribers wire line. This includes repetition of modulated radio waves received at the radiophone substation and also orig inating messages gathered up and to be put through the ainplier t" on the thransmitter T for broadcasting.

lt inav be explained here that the transmitter T for general purposes is assumed to he the standard wave length transmitter for the. local exchange area, to which all of the snbstations are tuned and upon which they depend both-for original messages and programs and tor those received and relayed from a distance. There are special cases` however. in which certain groups of radiophone subscribers may desire intercommunieation among themselves. and I contemplate therefore the installation of duplicates of this transmitter. which may be connected up for such group use. For example, a chess club desiring to meet. arranges a program. and at the appointed time its memhcrs attend at their radiophoncs. all removing their transmitters T from their hooks, while the radio .operator at the central station plugs up the multiples of their respective lines through their jacks J2 s, and connects them on to a special broadcasting `transmitter ot the type T. This plugging up mav be carried out in any desired manner. there being several ways well known in the art for thus connecting telephone lilies together. The radio operator then supervises the operation. since any one of the connor-ted snhsz-rihers may be speaking through the broadcasting transmitter to the others. and it is necessary to prevent interruption. The same might he said of any meeting of a group of people held in this nianuer. the most valuable feature of this part ot the invention being the absolute control atl'orded over the transmitted messages. The connection to the hrozulcasting transmitter is solely within the control of the radio operator at the jack or any other suitable form of switch. and he has it in his power therefore to cut oi connection at any time.

The cord circuit between plugs P2 and P in Fig. 3 is the same as the operators cord circuit in Fig. 2, but the radio operator also has special test cords such as that shown in the upper part of the figure connected to plug P. Here the keys K-K are. 0f standard construction, as in the other cords, and the test contact of the plug P* is connected through suitable resistance to the supervisory lamp s2 to the radio battery B', means such as the commutator pf' being provided to give special tone teston the test thimbles of the multiple jacks J J. J2; etc. It will be observed that the constant connection of the sleeve or battery wire. 24 at the radiophone substation to the bus wire 25 of the battery A.1 produces charging of that batter)7 by the constant flow of current therethrough from the main radio battery at the central oice. The amount of enervy thus delivered to the battery A, depends upon the size of the line wires. and the length of time available for such charging. As shown. the battery wire 24 is not cut oli except when the cut oil' relay L* pulls up which is only when the line wire is in use for conversation. With No. 19 line wires, and using` only the sleeve wire for conduction, it would be possible to safely transmit from one-hal amperes to two or three aniperes, according tothe line resistance and the voltage of the battery employed. lVhere this voltage is standard manual telephone voltage. say 22. and the single wire resist-ance to the substation is from 25 to 50 ohms. it would be possible to maintain the battery A, continuously charged. provided the time of discharge be not too long extended, and the charging be not interrupted by lother contingencies. such as the excessive telephone use of the line. In Fig. 4 of the drawing-'l'- show means for charging such a battery over a phantom circuit composed of the two sides of a magneto telephone line. Such a phantom circuit of course possesses still lower resistance than a single wire of the pair and correspondingly augments the amount of energy that may be delivered without a prohibitive loss. I wish to point out in connection with this, that radio instruments have recently been devised by the commercial radio corporations. and also bv the. United States Bureau of `Qtandards. which employ rectified alternating current. for lighting the filaments of the audion tubes. such currents being stepped -down to the usual voltage of the filaments from the voltage of house mains or feeder lilies. Using such a type of transformer and rectifier circuit. it is within the scope of my invention. to feed the filaments direct. and at the same time charge a floating storage battery A., if desired, by transmitting orer my line wire l9-l9-24 a sine ware current at. such voltage as will deliver the necessary energy.

Connected to the key K is a wire .30 containing a supplemental ke)` to connect the voltmetermr other suitable indicating instrument V and ground. The key K serves to connect the operators listening set, and also to put battery on the tip of the plug, by which means current is thrown out on the tip side 1S of the line.l then through extension 18 and back contact of relay L* to the winding of relay L5 and ground. The operation of these test keys will -be obvious from the description. Key L' enables the operator to take a reading on the battery A.. the line resistance being known. and the main batteries B. B being disconnected both at the cut ofi' relays L".l LT from the line itself and by the. back contacts of key K from the plug P. This is the most important test because the lamp filaments can be observed by the subscriber. and anv deects therein reported over the telephone. A companion test however enables the operator to detern'iine whether the radiophone instrument as a whole is functioning properly. assuming the transmitter T to be hung upon its hook H and as shown to have its mouth piece turned toward the emission orifice or diaphragm of the radio telephone receiver. Connection of battery B to the relay L causes the subscribers telephone set T. l. to be connect-ed to line and so to the multiple jack J plug P and the operators head phone connected through the listening key K. It is assumed of course that some form of broadcasting is going on from the transmitter T. so that the radio operator not only gets a test on the performance ot the individual subscribers radiophone, but also gets a test on his own broadcasting transmitter and on the relative tuning of the same with respect to the subscribers station.

lt should be noted that battery B in Fig. 3 is connected to the sleeve wires 17, 19a through the contacts of cut. off relays L, L?. energized in parallel with the line eut ott relays Lc and Ln either from the radio board or from the telephone switchboard. This enables the central office under all circumstances to keep a talking lintl balanced and supplied with current only through the connective cord or switch circuit. but as shown in Figs. 5 to S inclusive, the connections of the radio battery and that of the main battery are such that the balance is normally maintained. and current is supplied in such a way to the 4sleeve side of the line that no signaling apparatus on the telephone switchboard is aected thereby.

Fig. 5 shows the condition when a subscriber is talking through the telephone switchboard, the repeating coil I and the main battery B being shown as bridged across the line, and the radio battery B permanently connected through the sleeve side to the subscribers battery A1. Battery supply for both the subscribers transmitter and the. battery A, would as a matter of fact be drawn in due proportion from each of the centralized batteries B. B', and the resultant effect would be to divide the load between the two parallel sources, without changing the normal condition.

Fig. 6 shows the same arrangement when the subscribers telephone station is idle. and the. main battery B is bridged across the line wires between the two windings Z-Z ot' the subscribers line relay on the telephone switchboard; while the radio battery is connected in parallel to the sleeve side of the line through low resistance choke coils .T-.r

which do not appreciably reduce the poteni' tial placed upon the line terminal of the winding Z of the line relay. which, being exposed to balanced potentials, will not. be energized unless the subscriber calls.

Figs. 7 and S show corresponding conditions with the cut off relay L at the subscribers station for detaching the battery J., when the subscriber is talking.

It is not considered necessary to actually a( opt a permanent connection of the rado battery B because telephone conversations are usually brief and the time of use of the current flow in the sleeve wire would not be thereby greatly curtailed. At the same timi` I have provided means in the cut olf relays l Ln. L7 to disconnect the battery B when the lines are plugged up for conversation as at .r in Figs. 5 and 7, and when such cut olf relays are employed, the choke coils :v -ff may be omitted. so that a practically per feet balance may be had across the terminals of the line relay L. In other words` by using the cut on relays L. L", of Fig. 3. I am able to dispuse with choke coils -as and conneet the battery or charging generator of any type as shown in 'Fig'. 3.

Fig. 9 shows a modified circuit in which the telephone switchboard and radio switchhoard are provided with multiple line connections as before. the radio switchboard having connections to the radio broadcasting transmitter T and the radio operato:- having a full equipment of cords and plugs of known types symbolized at I". 'l`he sulstation is provided with a radio detector set and receiver 36. normally connected to the radio detector set through back contacts ot' the relay L5, which when energized by means of the opcrators key l at the radio board. will disconnect the receiver 36 and connect the radio detector set on its audio side directly to wires :SQ-53 and so through the contacts of eut oi relay L* to the line wires 16-17. As there is no battery shown for the detector set (which is typical only), the i...

llO

radio central battery feed is omitted in this iig-nre. which represents a very simple standardized system in which however the radio operator still has perfect control for all purposes ot the substation radiophone. It should lic noted that the continued energization of relai` L5 disables the radio set, and hy winding this relay so as to consume little current. this affords means to disconnect thc subscribers circuit from the radio switehboard until an inspector can make his rounds and the instrument can be removed.

It it be desired to have no grounds on the radio battery busses at snbstations. such as that on the A battery at station A', in Fig. 3, the ground Wires may be carried through contacts on switch hook H', opened when the hooks are up. Many other details of operation ma;7 be introduced and changes made. without departing from the scope of m v invention.

I claim:

1. A broadcasting system comprising primary high power stations using ditierent wave lengths, secondary stations having receiving radio sets tunable to the. dili'ercnt primary wave lengths and also having relay transmitting apparatus controlled h v the receiving sets and operatingr on a standard fixed wave length the same for all secondarvt` transmitters, and subscribers receiving radio stations grouped around each secondary transmitting station in its local area and tuned permanentlyv to the lined transmitting wave lengths thereof.

2. A radio system of intercommunieation having a plurality of standardized uniform receiving stations divided into groups, all said stations being tuned to one common frequency and of scnsitiveness limited to the areas covered b v their respective groups, a local transmitting station for each group working on said common wave length. and means for modulating the waves radiated from said transmitting stations as determined bv primary stations using variable wave lengths.

3. The combination of a pluralitiv of substations. a central station. a radio broadcastf ing transmitter at said central station. a radio receiver at each substation. a Wire line, connecting each substation with the central station and a telephone on each line at each substation, with means at the central station lo interconnect the substations for conversation through said wire lines. and means also at said central station supplying operating energy to the radio receivers at. the substations over said Wire lines.

4. A combined telephone and radiophone system, comprising a plurality of substations. a telephone and a radiophone at each substation, a central station common to said substations, line wires interconnecting the central station and the substations, and common means at the central station supplying operating current to both telephones and radiopliones over the said line wires. with means at each substation to differentiate between the two and to prevent interfcren.

5. In a broadcasting s vstem, a main station, a plurality of substations, means at said main station for generating and transmitting to the substations radio waves, means at the substations for receiving said waves, and individual wire circuits from the main station to the substations, with means at the main station controlling the wave re ceiving means at the substations over said wire circuits.

6. In a broadcasting system, a main station. a plurality of substations, means at said main station for generating and transmitting to the substations radio waves, means at the substations for receiving said waves, and individual ivire circuits from the main station to the substations, with a centralized source of current supply for the substation receiving means. connected to said Wire circuits and distributed thereby to the several substations.

7. A broadcasting system comprising a primary station, a secondary distributing station. and a plurality of local receiving stations related to the secondary station and all in permanenttune therewith, means at said secondary station to receive broadcast 'aves from the primar)1 station at its wave length. and to relaj,1 and redistribute the same in its own area at the standard wave length to which its receiving stat-ions are tuned, and means also at said secondary stationto determine when its transmitter is actuall;y tuned to the fixed wave. length of its receiving stations.

8. In a radio-telephone system, a transnzitfing station. a receiving station. a ivave transmitter at the transmitting station for radiatinggnodulated waves, a receiving set at the receiving stat-ion tuned to receive said waves, and a wire circuit connecting the. tivo stations with means to connect it to the. receiving set at the receiving station and means to transmit over said wire to the transmitting station modulated current corresponding to the said modulated waves.

9. In a radio-telephone s vstcm, a transmitting station. a receiving station. a wave transmitter at the transmitting station for radiating modulated waves. a receiving set at the receiving station tuned to receive said waves. and a Wire circuit connecting the. tivo stations with means to connect. it. to the receiving .set at thc receiving station. and means at. the transn'itting station to control said connecting means.

10. In a radio-telephone system. a transmitting station, a receiving station, a wave transmitter at the transmitting station for radiating modulated waves, a receiving set at the receiving station tuned to receive said waves. and a tvire circuit connecting thctvvo stations with means to connect it to the receiving set at the receiving station.l and means at the transmitting station to control said .connecting means through said wire circuit.

11. In a radio-telephone s vsteni, a transmitting station. a receiving station. a wave transmitter at the transmitting station for radiating modulated Waves. a receiving set at the receiving station tuned to receive s'aid waves. and a Wire circuit connecting the two stations with a source of energy for the receiving set located at the transmitting station and means for feeding said set from said source through said wire connection.

1Q. In a radio-telephone system, a transmitting station. a receiving station. a wave transmitter at the transmitting station for radiating modulated waves. a receivingset at the receiving station tuned to receive said waves. and a wire circuit connect-ing the two stations with a source of energy for the receiving sct located at the transmitting station and means for feeding said set from said source through said wire connection as determined at the transmitting station.

13. .l broadcasting s vstem comprising one or more primaatY transmitting stations operating at variable wave lengths` a localized secondary station having receiving means capable of variablel tuning to receive said variable broadcast waves. and transmitting means connected therewith for rela;7 modulation. but tuned for a fixed wave length. and a pluralitv of receiving stations related to said secondar;y station by vvire circuits, and having receiving sets tuned to the fixed wave length ot said station. with means controlled b v an operator at said secondariy station and operable through said wire circuit to maintain said secondary station transmitting means and said local station receiving scts in constant tune to a common wave length.

14. The combination of a. plurality of substations. a central station. a radio broadcasting transmitter at said central station, a

radio receiver at each substation, a wire line connecting cach substation with the central station and a telephone on each line at eac-l1 substation. with means at the central station lo interconnect the suhstations for conversalion through said wire. lilies. and means: also at said central station controlling the. operation of the radio receivers at said substations over .said wire lines.

l5. The combination of a pluralit)y of suhstations. a central station. a radio broadcasting transzntter at. said central station. a radio receiver at each substation. a wire line connecting each substation with the central station and a telephone on each line at each substation, with means at the central station to interconnect the substations for conversation through said wire lines, and means also at said central station for testing the radio receivers at said substations through said wire lines.

16. The combination of a pluralit)l of substations. a. central station. a radio broadcasting transmitter at said central station. a radio receiver at each substation, a Wire line connecting each substation vvith the central station and a telephone on each line at each substation. with means at the central station to interconnect the substations for conversation through said wire lines. and'means also at said central station for connecting and disconnecting the radio receiving apparatus at said substations from said wire lines.

17. The combination of a plurality of substations. a central station. a radio broadcasting transmitter at said central station. a radio receiver at each substation. a wire line connecting each substation with the central station and a telephone on each line at each substation, with means at the central station to interconnect the subst-ations for conversation through said wire. lines, and means also at said central station for connecting and disconnecting the radio receiving apparatus at said substations from said wire lines. said means acting automaticallv to break the radio connections to the wire line when it goes into service telephonically, and to reestablish the same when said telephone connection is taken down or released.

18. A radiophone system of intercommunication comprising a central station. a plurality of substations related thereto. and individual circuits interconnecting the same. each circuit composed, in operation, of a vvire line and an ether return or vice versa. and transmitting and receiving means located at the central station and at the suhstations, adapted to interrclate the ether waves and-tbe wire currents so that modulated radio wares may be transmitted in one` direction. and correspondingly modulated waves mav be returned over the wire circuit in the other direction.

19. A radiophone system of intercommunieation comprising a central station. a plurality ot suhstations related thereto. and individual circuits interconnecting the same. each circuit composed. in opera-tion. of a wire line and an ether return or vice versa, and transmitting and receiving means located at the central station and at the. substations. adapted to interrelate the ether waves and the wire currents so that modulated radio waves may be transmitted in one direction. and correspondingly modulated waves may be returned over the wire circuit in the other direction. with means at the central station to control the transmitting means at each substation.

20. A radiophone system of intercomes munication comprising a central station, a

municatiou comprising a central station, a plurality of substations related thereto, and individual circuits interconnecting the same, each circuit composed, in operation, of a wire line and an ether return or vice versa, and transmitting and receiving means located at the central station and at the substations, adapted to interrelate the ether waves and the wire currents so that modulated radio waves may be transmitted in one direction, and correspondingly modulated waves may be returned over the wire circuit in the other direction, with means at the. central station to control the receiving means at each substation.

21; A radiophonev system of intercommunication comprising a central station, a plurality of substations related thereto, and individual circuits interconnecting the same, each circuit composed, lin operation, of a wire line and an ether return or vice versa, and transmitting and receiving means located at the central station and at the sublstations, adapted to interrelate the ether waves and the wire currents so that modulated radio waves may he transmitted in one direction, and correspondingly modulated waves may be returned over the wire circuit in the other direction, with means at the central station to control the transmitting and receiving means at each substation. 22. A radiophone system of intercom- ,f' munication comprising a central station, a

plurality7 of substations related thereto, and individual circuits interconnecting the same, each circuit composed, in operation, of a wire line and an ether return or vice verse, and transmitting and' receiving means lo- 'cated at the central stationv and at the substations, adapted to interrelate the ether waves and the wire currents so that modulated radio waves may be transmitted in one direction, and correspondinglyr modulated waves may be returned over the wire circuit in the other direction, with means at the central station to control the substation operation.

23. A radiophone system of intercommunication comprising a central station, a plurality of substations related thereto, and individual circuits interconnectingr the same, cach circuit composed, in operation, of a wire line and an ether return or vice versa, and transmitting and receiving means located at the central station and at the substations, adapted to interrelate the ether waves and the wire currents so that modulated radio waves may be transmitted in one direction, and correspondingly modulated waves may be returned over the wire circuit in the other direction, with means at the central station to control the substation operation over said wire lines.

24. A radiophone system of intercomplurality of substations related thereto, and individual circuits interconnecting the same, each circuit composed, in operation, of a wire line and an ether return or vice versa, and transmitting and receiving means located at the central station and at the substations, adapted to interrelate the ether waves and the wire currents so that modulated radio waves may be transmitted in one direction, and correspondingly modulated waves may he returned over the wire circuit in the other direction, with switches at the substations controlling the relation of received and transmitted waves. and means at the central station for controlling said switches.

25. A radiophone system of intercommunication comprising a central station, a plurality of substations related thereto, and individual circuits interconnecting the same, each circuit composed, in operation, of a wire line and an ether return or vice versa, and transmitting andreceiving means located at the central station and at the substations, adapted to interrelate the ether Awaves and the wire currents so that modulated radio waves may be transmitted in one direction, and correspondingly modulated waves may be returned over the wire circuit in the other direction.

26. A combined telephone and radiophone system comprising a plurality of telephone substations, a telephone central station, line wires interconnecting them, a plurality of radiophone substations, a radiophone central station, means to transmit messages from said radiophone central station to its substations by modulated high frequency waves, means at the radiophone substations to transmit messages telephonically, wire connections between the radiophone sub'- stations and the telephone substations. and wire connections between the radiophone central station and the telephone central station?- 27. A combined telephone and radiophone system comprising a plurality of telephone substations, a telephone central station, line wires interconnecting them. a plurality of radiophone subtsations, a radiophone central station, means to transmit messages from said radiophone central station to its substations by modulated high frequency waves. means at the radiophone substations to transmit messages telephonically, wire connections between the radiophone substations and the telephone substations, and wire connections between the radiophone central station and the telephone central station, together with means controlled by a tele hone subscriber in calling to disconnect t e wire connections between his telephone and the corresponding radiophone.

2S. A combined telephone and radiophone 'dans system comprising a plurality of telephone substations, a telephone central station, line Wires interconnecting them, a plurality of radiophone substations, a radiophonecentral station, means to transmit messages from said radiophone central station to its substations by modulated high frequency waves, meansat the radiophone substations to transmit messages teleplionically, wire connections between the radiophone substations and the telephone substations, and wire connections between the radiophone central station and the telephone central station, together with means at each radiophone substation to control the actuating circuits of the radiophone and means also at said radiophone substations for effecting telephone connect-ion with the corresponding line circuit.

29. A combined telephone and radiophone system comprising a plurality of telephone substations, a telepione central station, line wires interconnecting them, a pluralityof radiophone snbstations, a radiophone central station, means to transmit messages from said radiophone central station to its snbstations by modulated high frequency waves, means at the radiophone substations to transmit messages telephon- 4ically, wire connections between the radiotion to its substations by modulated high frequency waves, means at the radiophone substations to transmit messages telephonically, wire connections between the radiophone substations and the telephone substations, and wirc connections between the radiophone central station and the telephone central station, together with a centralized source of current supply at each of the central stations, both said sources feeding independently through the line wires to the -ae... .fun g.: .1

telephone substations and to tbe radiophone substations respectively.

31. A combined telephone and radiophone system comprising a plurality of telephone substations, a telephone central station, line wires interconnecting them, a plurality of radiophone substations, a radiophone central station, means to transmit messages from said radiophone central station to its substations by modulated high frequency waves, means at the radiophone substations to transmit messages telephonically, wire connections between the radiophone substations and the telephone substations, and wire connections between the radiophone central station and the telephone central station, together with a centralized source of current supply at each of the central stations, both said sources feeding independently through the line wires to the telephone substations and to the radiophone substations respectively, and means controlled by an operator at the telephone cen- 8 tral station to disconnect the radiophone central battery from a line when in use for telephonie conversation.

32. A combined telephone and radiophone system comprising a central station and a plurality of subscribers stations with line wires interconnecting them, a telephone switchboard containing connective terminals of said line wires for interconnecting the lines for telephonie conversation, a separate radiophone switchboard containing multiple terminals of said lines, a telephone set and a radiophone set at each subscriber's station, and means for calling said sets separately from the telephone switchboard and from the radiophone switchboard respectively.

33. A combined telephone and radin i I system cmnprxsing a central statinn"ar| a plurality of subscribers stations with line wires interconnecting them, a telephone switchboard containing connective terminals of said line wires for interconnecting the lines for telephonie conversat' separate radiophone switchboard containing multiple terminals of said lines, a telephone set and a radiophone set at each subscribcrs station, means at the telephone switchboard for calling the said telephone set, and means at the radio switchboard for calling either set at will.

In testimony whereof I hereunto atlix my signature.

EDl-VARD E. CLEMEN T.