USRE17069E - clement - Google Patents

Description

- E. E. CLEMENT v SUBDIVIDED SERVICE SYSTEM OF RADIO BROADCAST DISTRIBUTION Sheet "ori inal Filed. un nzz, 1924 2 Sheets- Aug. 2a, 1928. Re. 17,069

E. E. CLEMENT SUBDIVIDED SERVICE SYSTEM OF R ADIO BROADCAST DISTRIBUTION 9x153). Filed Marbh 22, 1924 '2 sheets-s 2 I Q 7'0 /v z L004; OJC/LLITOE I Reissuecl Aug. 28, v 1928. n

UINITEDSTATEVS PATENT OFFI E."

EDWARD E. CLEMENT, or wasnmeronfnisrnrcr or COLUMBIA, ASSIGNOR no I I EDWARD r. COLLADAY, or WASHINGTON, ms'rnrc'r or COLUMBIALV a sunmvrnnn SERVICE sYsrmvr or RADIO BROADCAST nisrmnu'rroiv.

Original No. 1,522,362, dated January 6, 1925. Serial No. 701,128, filed March 22 reissue filed March 18, 1926. Serial No. 95,792..

My invention relates to systems of radio, broadcast distribution and has for itsv object the organization of a system capable of giving service to subscribers in regional groups, which may be related to each other by a general organization corresponding to the long distance telephone organization.

I attain my object by relating my subscribers in each area to one or more local central oflices,.by means of wired circuits, which may conveniently be telephone line circuits. Each subscriber is providedwith'. a

standardized form of receiving radiophone, and each central otlice is also provided with receiving radiophones, but much more elaborate and-powerful than those at the subscribers stations. Local service, that is to say," local broadcasting, is received by the subscriber direct, but when he desires any station except those that are listed as local, he secures a long distance connection'through his line wires to a central oflice radio receiving set capable of picking up and receiving the station he wants. The subscribers instrumentmay conveniently be a singletube regenerative set Wlth common battery con nections, taking all its current supply over the subscribers wired circuit. The central oflice radio sets may conveniently be superytalker or loud speaker.

heterodynes or the equivalent thereof, capable of receiving from distantstations and transforming the carrier wave length so as to relay or retransmit the original modulations over the subscribers line on a long care rier wave, preferably at superaudioj; frequency, such as 30 to kc. per second.

The advantages of this arrangement will be apparent on brief consideration. A single tube set is usually sufficient to give excellent results with local broadcasting, and by using a dynamic receiver, itis even possible to operate therewith a moderately loud table For distance work.

the antenna or equivalent wave collector is unnecessary, and the input side is connected through a. tuned coupler to the line circuit. The same tube detector in the subscribers y; set then receives the distant signals on long waves, without the necessity of elaborate tuning on, the part of the subscriber. local service, since no operators are required, a flat rate may becharged; but the long dis 5 tance service is strictly comparable to the For the i 1924. Application for long distance. service .in the I telephone ex-'5 change,'and calls for toll charges apportioned to the amount of service rendered, as well as the investment involved.

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

Fig. 1 1s a diagram of a subscribersstation.

Fig. 2 is a connected'diagram of the central ofiice end of the subscribers wired line circuit, showing terminal devices and switching meanstherefor. i Fig. 31s a dlagram showing a central ofiice superheterodyne receiver with its terminal switching device and an operators supervisory circuit.

Referring to the drawings, Figs. 1, 2 3 i in Fig. 2 will u r Fig. 1 represents a subscribers instrument 1 1 is a detector'tube with the usual filament 2, grid 3 and plate 4. 5 and 6 are rheostats, 7 is a choke coil, 8' is a telephone transmitter of standard type adapted to be bridged across the line wires9 and 10 by the'push button or key 11,, which however, opens as soon as pressure is removed from it. 12is thesub scribers headphone, 13 is a loop antenna for 1 local receiving, 14 is a tickler loop or regenerative coil, 15 is the usual tuningcondenser acrossthe loop, 1617 is a coupler for con necting the instrument to line'for long dis-i tance receiving,- 18 and 19 .are tuning condensers for the long distance circuit, 20 and 21 are radiofrequency choke coils included in the branch of the ordinary telephone set 22,

and 23- is'a gang switch adapted to connect the instrument for either long distance or local receiving to the telephone line wires 9-10.. or to disconnect it entirely therefrom,

at will. There are no batteries at the subscribers station, all energy for all purposes being supplied over the metallic circuit 9-10,

from the telephone exchange central ofiice.

shown in Fig. y

Fig. 2 shows one telephone line 9-10 with the switching terminals in the form of spring jacks J, a line relay L, battery B, cut-oil Y .this line with others for telephonic use, standard Western Electric No. 1 switchboard cord circuits are supposed to be employed,

which however, are not shown separate herein. The line 9-10, and any number of other lines assumed to be taking radio service, must be supplied with centralized current. during operation of their radio phones without keeping their signal lamps S burning, this applyingto both local and long distance s rxjice. "For local service. no other "connection is required at the centraloflice, but for long distance, that is to say, .for receiving from) distant stations, the subscribers line must be connected with a central oflice receiving instrument such as thatshown in Fig.3.: The

. This connection is shown in Figs. 2land as simplest form of connection is a direct'connection fromthe line wires'9 -10,Ito the bus bars 24-25 of the receiving'*instrument.

established by means of keys K' K which may be left normally closed,.fb'ecause radio frequency condnsers'are included in the circuits. .In such case'the subscriber can secure long distance .service 'by mer ely turningi'his own switch into. the proper position How: ever, this permanent connection would give hlm access to only onecentraloffice receiver,

' and he would be limited to the lprogram' received from stations selectedbythe central ofice operators". In order to give hima wider v I the balancing local oscillator circuit 45.

choice, I 'have indicated also interchangeable switchin means .consisting of plugs cooperating with the line jacks J on one receiving instruments. I

' [The amount of current consumedinQthe arrange'ment herein indicated at the sub-' scrib'ers station, .using 1 99 tube, is milliamperes.

Referringto' Fig. 3, the superheterodyne.

receiver therein shown of itself and as to. the

I details of its construction, .forms no part of the present invention. It maybe replaced by any convenient, form of receiver which will give equivalent range, ,selectivity,fandvolume of output. .As shown it comprises as its essential elements the follow ng: antenna circuit 26, coupler'27', inputcircuit 28, provided with' the usual tuning devices including condenser 29, and a load coil 30 which may be cut in or outbymeans of a shunting switch 31, first detector tube 32, coupler '33, andthree stages of radio; frequency amplification 34:,

' 35 and 36, each including a tri-ode' tube and transformer; also a local oscillator circuit 37 including the tube 38, and the usual coils to connect it with the input circuit 28. This oscillator circuit is tunable by means of the condenser 39 and the longwave switch 40 .to

any wave lengththrough the/usual rang'e'o'f broadcasting, as for example from 200 to 600 meters inclusive. To this circuit I have added a local modulating circuit 41, having a microphone transmitter 42, and a modulator tube 43 with the usual connections. .It is to be understood that thisarrangement is typical only, and may be varied without departing from the invention. The batteries A and. B for this receiving set are indicated in the upper part of the figure, and the power connections maybe varied, or additional batteries employed, as required in practice. The

,choke coil whichis usually included in the battery branch of the standard modulator circuit is also shown for convenience at 44 in the upper part of the figure.

"In order thata continuous program may be furnished when subscribers are'connected to long distance, giving them forexample a part of the program from a distantsta'tion, and then without changing the tuning or their connections, giving them other parts originate d locally'l add 'afsecond local oscillator circuit 45., having a coil 46 so related to the coupler 27 that localoscillations in the cir cuit 46 may take the place otthecarrier waves received from'a distant station, thusma'intaining the heterodyne effect and thefiow'fol long waves amplified at 34c, 35 and '36. to'the subscribefisline w ires9'-1'O'a=nd soflto his station receiver.

Local modulations may I then 'be imposed upon the long waves thus transmitted, by means of either the inodula-l tor41, or a; suitable'modulator connected "to For the purpose of tuningandsupervision, I have shown an operators receivingset 47. comprisingthe usual'elements of the tube 48. tuned input circuit 49. and a 50 by which the set may be "connected to the output circuit 51 of the s'uperheterodyne. 'lhe sa me operators set {l7 may be used witha plurality of main 1'e ?eivingsets,as indicatedby the multiplekeyhfl Als0,,the output circuit 51 of each long distance receiving set may have bus'jbars 24- 25 connected'to a plurality of switchi'ng terminals' shown as multiple jacks sertion when necessary of repeaters: and'-amp'hhersin the circuits 5243 leading to ind'i-j vidual subscriberslines.

It should particularly be observed in the present case that I have shown no second detector'in'Figf3, the out-put circuit '51' delivering a carrier wave at low or beat radio frev. quency, lhat is to say, transmission of the received and amplified waves from the rece iving set shown in Fig. 3 over the subscribers lines is at superaudio frequency,

versely, the telephonic currents or audio frequency waves, will not disturb the radio receiving, although this is notso important, be-

bridge with these cord circuits, and in the dia-.

- ing and bypass resistances.

cause in any combined system of this type, preference must be given telephone service.

At the subscribers station, the choke coil 7 guards the filament circuit from both radio and telephone audio currents while the high resistance in the plate circuit 54: of the order of 20,000 ohms) is suflicient to prevent shunt ing of the telephone apparatus at the stution 22.

Referring to Fig. 2, theplug circuit PP is typical of a long distance radio connecting circuit, by which the subscribers line 91O through a jack J or J and a trunk jack J or J a in Fig. 3, may be connected toreceive any desired distant station. This cord circuit is what is known as the standard VVeste-rn Elec tric No. 1 switchboard cord circuit, with listenin and ringin kevs IQ-K res ectivel D b v i 7 repeating coil RR, supervisory elements ss', supervisory relays r-r' and the usual balanc- The main battery B is supposed to have its busses connected in gram its positive pole is shown grounded as usual. For'special radio service, however, this ground may be omitted, a separate battery B being then employed. Since all of the batteries shown herein are at the central station, they may be combined into one, or may be made separate units, as circumstances and good practice may dictate. In exchanges car rying a heavy radio load, it may be advisable to provide a separate power plant, which may" conveniently be used in parallel relation to the telephone power plant,but the relation of the two load curves, that is the radio load and the telephone load, is such that only in very exceptional cases will their peaks coincide or even approach each other. The main telephone peaks occur approximatelybetween 10 and 11 in the morning, and 2 and 3 in the atternoon, with subsidiary peaks at one or two points between 4 and 7 grams usually come on between 3 and 4 in the afternoon and after 7 in the evening. Sub sidiary programs peaks would be between Con-.

. tors.

p. m. The radio pro- 2 and 3m the afternoon and6 ancl'7. in the evening, with occasional concentration at other hours, as for example when a special speech is broadcasted from Congress, or the like. The variations in thetelephone load are due to well established business and social conventions but the distribution of the radio load, (or programs) is to a great extent un der the controlof those who do the broadcasting. The diurnal variations in efliciency of wave transmission through the ether'render distance receiving more effective at night, and this coincides with the hours of leisure of the majority of subscribers, as well as with the low or flat portion of the telephone load curve. 7 In general therefore, it may be said that the two services will not conflict, but will sup-- plement each other according tomy system, and this being so, furnishes reason for pre senting herein a connecting circuitof the type shown at PP' in Fig. 2. In a great many exchanges the same ,switchboards and the same operators may be employed to switch radio connections that are employed to switch telephoneconnections. The circuit P'P is therefore made convertible, by means of switch contacts 5a, 55, 57 and 58. The first two of these control the connection of a radio coupler 59-60, and the other three control the continuity of the ordinary cord circuit connections 61, 62 and 64 to the plug P, from the battery B and repeating c'oil R. The conductors 6465 and'66 leading to the plug P are left intact at all times in order to furnish operating current to the subscriber, and to supervise the connection by means of the lamps s, with the ancillary purpose of op-. erating the cut-off relay G and-putting a special tone test on the multiple jacks, so that the line will not test busy to telephone opera- This tone test 68 is controlled by a switch 67, closed when the cord is in use for radio use, and opened along with the contacts 5 i.55 when in use for telephone service. \Vlien the. contacts 54, 55 and 67 are closedfor radio service the contacts 56, 57 and 58 are opened, although it has been found that this is not absolutely essential to good radio transmission. One winding of each coil R is left 7 between the battery B and the conductors 64 and 66, and may be supplemented by a radio choke coil, if the battery B is the same as or is connected with the main telephonebattery, the purpose being to keep the radio waves ofi the battery busses. i

As previously pointed out, instead of being connected through-the cord circuit P-P, the subscribers line 9-10 may be connected to the centralofiice distant receiver of Fig. 3 by means of the circuit .52-53, provided with switches at both ends. As a matter of fact, the circuit 5253, instead of being individual, may be common toa'number of lines as indi cated by the branch wires 52* and 53*, the single pair 52-53 thus becoming an extension of the output bus. I The transmissionover the line 9-40 is facilitated by turning both ends of the line, as well understood in the art, and I therefore include a coupler 6970 and a tuning condenser 71, the elements 70- -71 being bridged across the line by the key K. These elements in conjunction with the corresponding elements 17--19 at the subscribers station not only render the transmission better, but'e'fi'ectuall'y absorb the radio waves .and block audio waves over the line. The

' also shown a tuning condenser 72; and it is to be noted that in the output circuit 51 (Fig. 3) there are two fixed condensers, intended to prevent any possible short-circuiting of telephone or battery currents through the secondary of the transformer :74. These may be omitted if tuning condensers are employed as at 72 in series with the coil 59.

The operation of my system thus described isas follows: 1 i

The .su'bscribers station in'Fig. 1 is shown With all parts in a condition of disuse. If the subscriber desires telephone service. he removes his'telephone receiver from the hook and thereby signals central through the parts 'L and S, as usual. A cord circuit which may be that shown at PP, with the contacts56, 57 and 58 closed and the contacts 5155 opened, is then employed,-

to answer, test," connect, ring the wanted subscriber, and superviseyas usual. If, on

the other hand the subscriber desire s'radiophone service,-'he sets his switch for local or'long distance, as the case may be. Assum ing that he desires only local receiving,

and that sufficient battery current for the filament '2 may flow through the line without disturbing the central oflice signal or protective devices, he'need do nothing further.

If he desires long distance receiving however, he calls the'operator in the usual way, either by means of his ordinary telephone set, or by means of the transmitter, '8 controlled by the push button 11 associated with the radio set. In'accordance with standard practice, distant stations will be numbered. and in response to the inquiry Number, please, the'subscriber gives the number, as for example Radio, 412, The'operator then connects him with the superheterodyne receiver of 3 which can give him the station he wants, and if necessary communicates at the. same time through an order circuit with the radio operator in charge ofthe radio receiving apparatus. As an alternative. and in accordance with long distance practice, the'local or A operator may answer the call and learning it is for radio may communicate with the radio operator over an order circuit, and the radio operator will then connect with one of the multiple terminals of the calling subscribers line, ascertaining direct from the subscriber what station he wants, andsetting up the necessary radio connections accordingly.

This arrangement has the obvious advantage of avoiding a tie up of the operators cords on an A board or answering positions.- This automatic in its mode. of operation. This method has also the additional advantage that the calling and switching tothe radioboard may be simplified byestablishing a conventional form of radio calling, which may be made by" flashing line lamp S, The A operator perceiving a line lamp to flash, would knowthat the line desired long distance radio connection. and, would pass-the call to the radio operator as before stated. using anxorder circuit. If the lamp burns steadily, it would indicate'a desire for telephone connection, and where the subscriber is using his instrument for local radio receiving there would preferably be no indication at all on the lamp S. v

hat I claim is:

1. In a 'radiophone system of broadcast distribution, a central station and lines .lead ingftherefrom to subscribers stations, radio phone receivers at the subscribers stations arranged to be supplied with operating current over the line, means at the central station vfor supplying current over the lines. broadcast transmitting means at the central station, link circuits at the central station and switchin means associated with .a link circuit for adapting it either to the interconnection of subscribers lines with each other or to the connection of said transmitting means with subscribers" line. a I

2. In a radiophone system of broadcast 1 distribution, a central station and. subscribers stations with lines interconnecting the radio receiving sets at the subscribersstations connected with the line to take operating current therefrom, means at thecentral station for supplying said current over the line, means for transmitting a modulated super,

' audio frequency carrier current over the lines, a receiving circuit at each subscribers station tuned to the frequency of said carrier current, and means at eachsubscribers station for connecting the input side of the said 1 radio receiving set through the said carrier current frequency tuned receiving circuit to the line. i

3. In a radiophone system of broadcast distribution, a central station and subscribers stations, radiophone receiving sets at the subscribers stations, an antenna at each subscribers station, means for operatively connecting the input circuit of the subscribers set with either the antenna or the line, and means operable upon the switching of said input circuit from the antenna to the line to automatically change the tuning of said receiving set from short wave lengths to long wave lengths.

4. In a radiophone system of broadcast distribution, a central station and subscribers stations, a network of wire lines interconnecting them, radiophone receiving sets at the subscribers stations, a receiving antenna at each subscribers station, means for distributing broadcast matter over the lines by wired radio and means at a subscribers station for switching the subscribers radio receiving apparatus from radio to Wired radio.

5. lna radiophone system of broadcast dis-v tribution, a common battery telephone system having subscribers stations and lines interconnecting the same, radiophone receivers at the subscribers stations, means at a subscribers station for receiving radio broadcast on the radio receiver, means for distributing broadcast matter over the telephone lines by wired radio, and means at the subscribers station for switching the subscribers radio receiver from radio to wired radio.

6. In a radiophone system of broadcast distribution, a central station and lines leading therefrom to subscribers stations, radiophonereceivers at the subscribers stations arranged to be supplied with operating current over the line, broadcast transmitting means at the cen-' tral station, link circuits at the central station for connecting said radio transmitting means with the subscribers lines for transmission thereover by wired radio, means for signalling the central station from the subscribers station over the line, and means at the subcribers station for switching the radio receiving set from radio reception to wired radio reception.

7. In a radiophone system of broadcast distribution, a central station and lines leading therefrom to subscribers stations, radiophone receivers at the subscribers stations, broadcast transmitting means at the central station, link circuits at the central station, switching means associated with a link circuit for adapting it either to the interconnec-- ripeo tribution, a central station and subscribers stations with lines interconnecting the same, radio receiving sets at the subscribers stations, a radio receiving antenna for each subscribers receiving set, means for transmitting a low frequency carrier current over the lines, a low lrequency receiving circuit at each subscribers station tuned to the said low frequency carrier current, and means at each subscribers station l'or connecting the input side of the said radio receiving set to either the antenna circuit or through the low frequency tuned receiving circuit to the line.

9. In a radiophone system of broadcast distribution, a central station and subscribers stations, radiophone receiving sets at the subscribers stations each comprising a thermionic tube with plate and filament circuits therefor connected to the line circuit for current supply, a common source of current at the central station connected to the line and of a suliicient voltage to operate said plate circuits thereover, voltage reducing means connected between the line and the filament circuit, an antenna at the subscribers station, means lor operatively connecting the input circuit oi the subscribers set with either the antenna or the line, and means operable upon the switching of said input circuit from the antenna to the line to automatically change the tuning of said receiving set from short wave lengths to long Wave lengths.

'10. In a radiophone system of broadcast distribution, a central stat on and subscribers stations, radiophone receiving sets at the subscribers stations each comprising a thermionic tube with plate and iilament circuits therefor connected to the line circuit for cur rent supply, a common soin'ce of current at the central station connected to the line and oi a sufiicient voltage to operate said plate circuit thereover, voltage reducing means connected between the line and the filament circuit, a receiving antenna at each subscribers station, means for distributing broadcast matterover the lines by Wired radio,and. means at a subscribers station for switching the tem' having subscribers stations and lines interconnecting the same, radiophone receivers at the subscribers. stations supplied with operating current from the central station over the lines, means at the subscribers station for receiving radio broadcast on the radio receiver, means for distributing broadcast matter over the telephone lines by Wired radio, and means at the subscribers station for switching the subscribers radio receiver from radio to wired radio. I.

In testimony whereof I hereunto atfix my signature. I

EDWARD E. CLEMENT.

Images