US1754877A - Radio telephone system - Google Patents

Description

April 15, 1930. E. E. CLEMENT RADIO TELEPHONE SYSTEM Filed Feb. 9, 1924 4 Sheets-Sheet gmentot April 15, 1930. E. E. CLEMENT RADIO TELEPHONE SYSTEM Filed Feb. 9, 1924 4 Sheets-Sheet 2 A ril-15,1930. Ef CLEMENT 1,154,817

RADIO TELEPHONE SYSTEM Filed Feb. 9, 1924 4 Sheets-Sheet 3 April 15, 1930.

E. E. CLEMENT RADIO TELEPHONE SYSTEM Filed Feb. 9, 1924 4 Sheets-Sheet 4 Patented Apr. 15, 1930 UNITED STATES PATENT OFFICE EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO EDWARD F. OOLLAIDAY, OF WASHINGTON, DISTRICT OF COLUMBIA RADIO TELEPHONE SYSTEM Application filed February 9, 1924. Serial No. 691,825.

'My invention relates to radiowire systems of broadcast distribution, with special reference to the use of electric light, power, railway or other wired circuits, so that the wires may be employed for transmitting modulated waves, metering, and other purposes. This application is a continuation in part .of my,

phone system, either automatic or manual,

and broadcast to said instruments from a central station which may be the centralpower station or a substation belonging to the system or the telephone central station or a substation thereof. In any case the radio operators are provided with telephone switching means whereby they can connect. themselves to various radiophone stations for purposes of observation and supervision of the system. At the radiophone stations, I provide local switching connections to the current mains, and through these connections when closed eifect current feed to the instrument for metering, and also bring to the instruments modulated carrier current transmitted from the central station referred to. This central station is provided with amplifying and modulating apparatus for original matter, and with relaying apparatus for distributing to the local subscribers signals received from a distance. By thus organizing a combination system, it is possible to unify the service in all respects-and to make service charges on a fair and accurate basis. I may meter the service, using asimple constant speed current meter, with means to register units of time use, or to register the number of times an instrument is used. In the latter case, the

meter may be reduced to ultimate simplicity, being in effect nothing more than a record- 1ng magnet cooperating with a suitable switch service. 11 any case, it' is intended that the subscribers instrument shall be adapted to receive by pure radio waves from a distance, for which no meter charge should be made, and also adapted to receive modulated waves transmitted over the wired network, for which a charge should be made. For this purpose, I make the subscribers in strument with an antenna circuit and coupler coil, a detector tube, and preferably one stage of audio amplification to permit the use of a loud speaker, together with heterodyne coupler. connected through switch contacts to the wired network, so that the instrument will function as a superheterodyne receiver when taking waves from both the ether and the wires. I further provide the plate circuit with a tickler coil, normally disconnected therefrom and the plate circuit closed on itself, but adapted to have its circuit closed through plate when the heterodyningcigguits to the wirednet work are broken. Thus the instrument will function as a heterodyne receiver, or by disconnecting the heterodyne coupler and connecting the tickler coil, may 7 be used to receive pure radio waves from distant stations direct. The meter circuit will be closed-"onlywhen the heterodyne circuit is closed. I

It is to be understood that the principles herein set forth are not limited to the use of lighting power or railway circuits as such, or to any particular type of telephone system, although I shall describe and claim herein a manual telephone exchange system of standard Western Electric type.

It is to be further understood that I am not limited to the specific circuits and connec tions shown by which my subscribers instrument is made a combination receiving instrument, and especially a combination of heterodyne and regenerative receivers, for the purposes stated. Such an instrument may be useful in other inventions, and it is also to be observed that the method of metering, by which a record is made of the pay service stead of time of use.-

only, may be useful for various other connections.

My invention is illustrated in the accompanying drawings, in which: t

Fig. l is a typical diagram showing a radiophone system combined with an electric lightingi system.

. 2 is a diagram of a single radiophone Fig. 7 is a similar detail of a modified form of meter to record number of connections in- Referring to the drawings, Fig. 1 is a condensed diagram showing an electric lighting system with a central power station 0, five transformer substations, C, C C", C, C, consumers mains M fed from the substations, and feeder mains M, distributing the power from the main generating plant typified by G to the substations. At the central station Sw indicates the usual main switchboard, and Sw a supplemental switchboard for urposes to be described. -From this board Sw' communication wires 35, 37, 39, 41

extendout to the substations, one pair of more.

accompanying each feeder cable in the ducts. At each substation a small switchboard S10 is provided, equipped with an automatic selective switch 36, 38, 40 or 42, having a switch arm or wipers connected to the incoming, line I 35, 37, 39 or 40, and contacts over which the wipers are stepped in operation, to connect with local lines to consumers radiophone stations. Thus at substation C the switch 36 has contacts connected to wires 43, 44, which extend from that substation to the radiophone stations 43", 44. This same substation C carries a feeder main M to a second transformer station 0, and the accompanying communication wire 45 extends to a switch 46 at said substation, from which wires 47, 48 extend to radiophone stations 47, 48*. This subdivision of the system requires an extra digit in the number transmitted from the central operators dial 32 or switchboard 811) at central station C, the switches 34, 36, and 46 corresponding to first and second selectors and connectors in an automatic telephone system. No detail of the switching circuits or the operating mechanism of the automatic switches is given herein, as such circuits and switches are well known, and of themselves form no part of the present invention, the

main feature of which as regards the communication circuits, lies in the ability of the central ofiice operator to automatically connect himself to any part of the system through the minimum number of wires, comprising in this case a single pair from the central station to each substation, and single pairs diverging therefrom to the further subdivisions of the system. The last link in any of these circuits is the individual drop wire, extending from a terminal box to'the building in which current is to he used. These drop wires are relatively short, and we contemplate employing them for a double purpose, viz., for communication by telephone or otherwise over the wires, and as antennae for the radiophone instruments, where found expedient or desirable. This will be described hereinafter.

Transformers K are the substation transformers, and transformers K are the house or pole transformers feeding the consumption circuit M from the house mains M. The consumption circuits M carry translating devicessuch as lamps L, and also supply current to the radiophone receivers RR, to be presently described. These radiophones are all standardized and of uniform design and construction, and are calibrated and locked-when installed, so as to receive on common wave length only, i. e., thewave length alloted to the broadcasting transmitter RT at the central station C. This transmitter maybe located at some other point than the central power generating staerator at switchboard Sw, who is also to listen in andobserve the operation of the outlying instruments.

The central station is equipped with a local oscillator 0G to send waves at heterodyning frequency over thewired network M, through the switch -60 and the coupler CC to the switchboard Sw. These waves may be modulated by the local modulator LM.. The central station may also transmit by pure radio waves from the local oscillator OC', and these waves may be modulated by closing the switch 62-62, the waves from oscillator OC being left unmodulated if desired by opening the contacts 61-451.

The net result of this arrangement is that the subscribers instrument in Fig. 2 can be supplied with pure radio waves over the ant'enna 25, modulated or umnodulated, with heterodyning waves over the lighting circuits M, M, M, either unmodulated or modulated; and these waves may either be relayed from the central ofiice after radio amplification, or they can originate there.

Referring now toFig. 2, we have therein shown a portion of the Y power and communication circuits, one radiophone RR, and

the general arrangement of a radio operators sumers station (telephones being provided) may be connected to the radio transmitter for broadcasting as provided in Reissue Pat- .ent 16,231 hereinbefore referred to., This e11- ables the operators to bring in contributions to the broadcasting programme, and also to organlze groups of subscribers for broadcast meetings on subjects of common interest,

. such as chess games,-debates, etc. In such cases, thevarious subscribers lines 30*, 31 of any desired group are all plugged in on the sameScircuit 30.31 to'the central broadcastingfstation, where they may be put on the transmitter RT asa group through ack J 5 and "suitable amplifying apparatus.

The feeder-did extends from transformer substation C to the house transformer K which supplies\main M carrying lamps L. To this main a shcket is connectedwith which a plug P cooperates to connect the feed wires 17-18 of the radiophone receiver RR. Current for the meter RM is supplied through this circuit. This meter as shown comprises a motor 22 driving a Veeder counter, 24, through a worm gear 23, and taking current through branch wires 1920. The motor may be of any standard type adapted to the current employed. In tne present case alternating current at cycles, single phase, is presupposed, and the'motor may be a single phase synchronous or split phase machine, or

any other capable of operating at constant speed on a constant potential. The Veeder counter is marked in time-use units.

In the receiving instrument 28 is a coupler, on the input side of the combined heterodyne and regenerative receiver. vWaves received over the antenna 25 pass through the tuned circuit to the tube detector 6d, while. waves received from the wired circuit M pass through the closed switch contacts 3 to the heterodyning coupler kc and thence to the detector. The combined input is detected and rectified and by the amplifier tube at delivered to the loud speaker 56 through the transformer 14;. The plate circuit of the tube ta? is normally closed at 3,1, which can be opened and contacts .2 closed to connect the tickler coil to in the plate circuit, this tickler being incharge is made.

ductively associated with the coupler coils 28.

To receive combined waves over the wires and the ether, switch a is opened and all the switch contacts 3/ are closed; while to receive a single train of pure radio only, which would be public broadcasting service, the contacts y are all opened, and the contacts z closed. This cuts oif the energizing current from the meter, cuts-off the heterodyning coil he, and connects the tickler coil to. It is to be noted thatthe subscriber in this arrange ment and in many other similar hook-ups,

can receive with practically equal efficiency over either circuit, by heterodyning or regeneration, but the former will give more satisfactory results because of the greater amount. of energy and better service delivered over the wires, for which of course a In practice, the miscellaneous independent use of the subscribers instrument would he covered by a flat rental charge.

It should be observed that if desired the co'ntactsz may be closed and the associated contacts y may be opened, in order to add the regenerative effect to the heterodyning through the two input circuits, a separate switch being then provided for the tickler coil and plate circuit, instead of the gang switch contacts shown in Fig. 6.

For purposes'oftesting and observation, the telephone transmitter T may be located in proximity to the horn of the receiver 56. The telephone equipment shown is of magneto type, (magneto-generator and ringer being omitted) with induction coil I and receiver t.v When placed as shown and plugged throughto central station C, the radio op erator canlisten to the receiver 56 over wires 30-3O-3131 Referring now to Fig. 3, we have shown therein part of a system similar to that of Fig. 2, but employing an ordinary telephone exchange line 15-16 for a communication circuit. In this case the radio operator at station C has a telephone Tt connected to'a telephone exchange switchboard G" from ceiver RR are shown. In this instrument, 1-

indicates balancing resistances, 2 the radio frequency transformers, 3 the audio frequency transformers, 4 is a telephone transformer, 5 the armature of a loud speaking receiver, .6 the field of the loud speaker, 7 a vacuum tube rectifier, 8 a plate voltage tube rectifier, 9 (as-stated) the power transformer,

10 the filament rheostat, 11 a condenser of one the loud speaker. No claim is made herein to this instrument or, its circuits, and it is presented as typical only of any instrument suitable for use with the current supplied to the mains M.

'The antenna circuit is completed from ground 29 and coil 28 or the equivalent, by wire 25 to plug P, and so to the lighting mains which thus become part of the antenna. We have shown condensers 26-27 of small capacity in this circuit, but any other known means of preventing current leakage from the, lighting mains may be employed.

For rendering measured service, meter RM is provided, its circuit wires 1920 being bridged across the main feed wires 1718 ofthe radiophone set. The constant speed motor '22, gears 23 and counter 2d are the same as before. The meter records time-use, as the circuit 17-18 is closed only when the radiophone is in service. An advantage in having the meter forming a part of the instrument equipment is that the entire equipment is thereby made portable and may be carried to any point where ]acks J a or J b are installed, in the same or another building, and the serv ice will be uniformly metered for all such use. In order topermit such portable use, and for other purposes to be explained, the various parts are assembled in two separate units, as illustrated in Fig. 4, wherein RU is a box containing the power'supply, including in the case described, the special transformer 9, with five windings and the rectifier tubes 7 and 8; and AU is a separate box containing the amplifier tubes, amplifier transformers, and other apparatus. By thus dividing the set, advantages are gained, viz., the amplifier isjemoved from immediate proximity to the power supply apparatus, from which it might pick up a hum, and second, the power supply box can be made interchangeable with others containing different sources of supply, such as a set ofstorage batteries or a special equipment for adapting 1-10 volt direct current supply to the feed circuits of filaments and plates, etc. For this purpose a small motor transformer may be employed, or suitable rheostats and switches. In any case the meter motor is placed in the same box RU with the power equipment and the dial arranged in the side of the box to be read from the outside. Where the box contains a storage battery, the meter is thus made a part of the battery unit RU and taken to a central station or 'service station for charging. We contemplate organizing this service on such a basis that three classes can be provided fori first those consumers who have alternating current supply on their premises, as herein illustrated; second those who have direct current ing, where the meter will be be read and the record of such readings will be periodically used in billing for the service. To save time in such cases, and according to similar practice. in other lines of business, the battery units RU may all be made interchangeable, and the meter readings of each unit' will be recorded, on receipt and delivery. By this means, a discharged battery can be exchanged at the service station for a freshly charged battery without delay. As the keeping of such records is in accordance with well known principles, detailed description is unnecessary. I lay no claim herein to a detachable power unit broadly, but I shall claim herein the interchangeable unit feature, whereby different sources of current supply may be furnished for a standard AU unit or instrument, and shall also claim the mounting of the meter as apart of the power supply unit so that it will always furnish a record of time use. An incidental feature of this arrangement is that the box containing any RU unit may be sealed, so that the battery, transformers, switches, rheostats and meters are secured against interference and the meter readings thereby made dependable.

A fourth class might be added to the foregoing, including those who have no direct connection to the lighting or power mains, but have local current supply of their own. This includes surburban and other places equipped with so-called farm lighting outfits. The voltage of such small generating plants is not usually standard, but lower than that on the city distribution systems, hence special RU units must be provided for such service, preferably containing storage batteries to give standard voltages, and a suitable charging set. In any case, regular or special, the meter forms a part of the power supply unit of the radiophone, and is always connected, as herein described, when the instrument is in use. Where standard municipal current supply is available, the inspectors who read the lighting meters will also read the radiophone meters.

Returning to Fig. 1, the drop wires such as 43, 44, 45, leading from the local distribution centers or substations to the consumers radiophone stations, may be used as antennae instead of the separate antennae indicated in 2, or the lighting mains indicated in Fig. 3. In such case plug and jack connections similar to PJ a of Fig. 3 may be em ployed, or the anteimia connection may be permanent, the drop wire being connected direct to the wire in Fig. 3, with or without the "interpositionof small capacity condensers, as

may be found desirable. The result of making such a connection is shown in a typical diagramin Fig. 5, wherein BB is the radio phone, 0 the central olfice, -451 the communication wire, and T the central operators telephone. The communication wires ary circuit of the loud speaking transformer on the audio side of the set, so that no telephone is required at the radiophone station. The circuit 3031 is thus at once antenna and an extension of the localradio receiving circuit, over which the operator can test and listen directly. v

In the system ofFig. 2, a subscriber'desiring radio service, plugs his set in on the line M through means of the plug-P, which supplies. power to his receiving set RR through i conductors 17 -18 and to the meter motor 22 through branch wires 1920. The meter therefor starts into operation and continues toerecord the length of time the connection is maintained. The receiver RR, being supplied with power will now pick up the broadcast signaling to which it is tuned through the antennacircuit 2528 and translate it into amplified audible signals through the transformer 14 and loud speaker 56 in a manner as will be understood by those skilled in the art. In the present instance the receiver ER is tuned to the transmitting station RT so that broadcast matter .is received there-- from.

Should the subscriber desire connection with the central ofiice 0 he can doso through the use of his telephone set T, t over the line 30-31 through the plug and jack connection J Fe-P at the substation G and over line 30-31, to station G, all in the usual manner as well understood in the art of telephone communication, details such as switching and 30 31 v are here shown connected also to the seconders loudspeaker through the transmitter T, which observation enables the operator to adjust the transmitter to the subscribers instruments which latter are permanently tuned to a common predetermined wave length.

Where storage batteries are used as a source of power supply with the time use metera part of the power supply unit, as indicated.

in Fig. 4 theoperation is similar to that previously described except that instead of the subscriber connecting with the common distributing system he connects his set with the portable source'of power supply, receiving the signalling energy through his independent aerial as in Figs. 1 and 2, or a distributing system used as an aerial as in Figs. 3 and 5.

' The storage battery and metering features described above and nbt claimedherein, are

network, and other means for broadcastingsimultaneously, properly related unmodulated waves through the ether.

In testimony whereof I hereunto affix my signature. I r a EDWARD E. CLEMENT.

signaling means and'their use being omitted I from the drawing and description for the sake of clearness. Similarly, the central station operator may be connected with the subscribers telephone set over the line 30-81 and 3O '31? through the substation C5. Thus the subscriber may communicate with the cen- I tral station for information or to report condition of service. When it is desired to have the subscriber broadcast, the above described connection is established and further extend.- ed through jacks J 2 and J 5 and suitable cord and plug connections, not shown, to the radio transmitter RT. 5

F or" supervision of the quality of reception by the subscribers radio receiver, and controlling the quality of reception, the operator.

at the central station C makes use of'the telephone connection above dGSCIlbBd tO listen in on the audio reproduction from the subscrib-

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