US1580409A - Trunking system of radio distribution - Google Patents

Trunking system of radio distribution Download PDF

Info

Publication number
US1580409A
US1580409A US9355A US935525A US1580409A US 1580409 A US1580409 A US 1580409A US 9355 A US9355 A US 9355A US 935525 A US935525 A US 935525A US 1580409 A US1580409 A US 1580409A
Authority
US
United States
Prior art keywords
line
station
subscribers
relay
central
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US9355A
Other languages
English (en)
Inventor
Edward E Clement
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EDWARD F COLLADAY
Original Assignee
EDWARD F COLLADAY
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by EDWARD F COLLADAY filed Critical EDWARD F COLLADAY
Priority to US9355A priority Critical patent/US1580409A/en
Priority to GB3240/26A priority patent/GB247550A/en
Priority to FR613000D priority patent/FR613000A/fr
Priority to DEC37842D priority patent/DE567672C/de
Priority to CH122696D priority patent/CH122696A/de
Priority to BE332313D priority patent/BE332313A/fr
Application granted granted Critical
Publication of US1580409A publication Critical patent/US1580409A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/65—Arrangements characterised by transmission systems for broadcast
    • H04H20/76—Wired systems
    • H04H20/82—Wired systems using signals not modulated onto a carrier
    • H04H20/83—Wired systems using signals not modulated onto a carrier not sharing the network with any other service
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/65—Arrangements characterised by transmission systems for broadcast
    • H04H20/76—Wired systems
    • H04H20/77—Wired systems using carrier waves
    • H04H20/81—Wired systems using carrier waves combined with telephone network over which the broadcast is continuously available

Definitions

  • the present invention is a continuation in part of my copending application Serial No. 754,406, filed December 6. 1921; it re. lates to systems of radio broadcast distribution, and has for its object to organize such a system so that a program may be originated, relayed and distributed over a large area, uniformly and in a systematic and orderly manner to aut-l'iorized users or subscribers who will get the full benefit of the use of vacuum tubes in receiving and amplifying without the necessity of maintaining tubes at their stations, the tubes used by the subscribers in receiving being located at central points where supervision, maintenance power supply and control may be centralized and put under the care of expert operators.
  • both relay distribution and supervision of the broadcast service for a group of subscribers is carried on at the central station or exchange local to the group.
  • the object of the present invention ditfers from the aforesaid in that a district relay station and radio studio common to several subscribers central stations, is provided for distributing broadcast matter to the central stations by radio, the central stations distributing the broadcast matter to their respective sunscribers by wire, while supervision of the broadcast service as distributed by the several central stations and received by the subscribers is delegated to one of the central stations, and supervision of the broadcast service as furnished by the district station and received at the several central stations is reserved by the district station.
  • the invention is applicable to manual automatic or so-called semi-automatic or automanual telephone systems. the principles involved not being changed by dilferent methods of effecting or controlling the neces sary electrical switching connections.
  • Figs. 1 and 2 indicate diagrammatically, the telephone exchange portion and the broadcast distributing portion of a subscribers central station forming part of my system.
  • Fig. 3 is a diagram of the district radio relay station and studio.
  • Fig. 4 is a diagram of the primary supervisors station at the main central station.
  • Fig. 5 is a schematic diagram showing the system as applied to a district containing several local or exchange groups.
  • this shows the essential cir cuits of an ordinary telephone exchange system in which JJ' are line terminal jacks forming the terminals of telephone lines leading to stations to be interconnected such as the subscribers station A. These jacks are arranged to be interconnected through the usual answering and calling plugs P-P' forming the terminals of the usual common battery cord circuit shown.
  • the central office terminals of each line are provided with the usual line relay L, line lamp L and cut-off relay L lVhere service is to be metered a recording meter M is also individually associated with the line.
  • the circuit arrangement here shown is that of the standard multiple switchboard, common battery, telephone exchange system, and as such is well understood in the art further detailed description thereof will be here deferred and brought out later in the description of operation.
  • multiples 1, 2 and 3 representing multiples of the tip, sleeve and test or cut-ofi' circuits, respectively, I provide a fourth conductor 4 leading from a contact on the line relay along with the multiple conductors 1, 2 and 3 to the broadcast distributing system diagrammed in Fig. 2.
  • Fig. 2 shows the broadcast distributing system of which the portion to the left of the dotted line is situated at the central ofiice and connected with the subscribers telephone line terminal apparatus of the telephone central C (Fig. 1) through conductors 1, 2, 3 and 4, while the portion to the right of the dotted line in Fig. 2 is situated at the subscribers substation and connected with the subscribers telephone substation apparatus A (Fig. 1) through the multiple conductors 5 and 6.
  • the subscribers line multiples 1-2 terminate in the spring contacts 7-8 of a jack 9 which contacts are arranged upon the insertion of the dummy plug 10 to be spread apart to engage with the stationary contacts 11-12 to extend the connection of the multiples 1-2 to conductors 13-14.
  • the conductor 13 connects with the positive terminal of the common central ofiice battery B through the winding 15 of a repeating coil 19 while the conductor 14 connects with the negative terminal of the battery B through a sleeve or supervisory relay 42 and the winding 16 of a repeating coil 20.
  • An audion tube 37 individual to the line, is also provided which is arranged with its output or plate circuit conductors 21-22 connected in series with the windings 17 and 18 of the repeating coils 19 and 20 and a plate battery B.
  • the input circuit of the tube 37 is arranged to be connected through contacts 23-24 on the supervisory relay 42 and conductors 25-26 to the program busses 27-28 to which are connected the audio output terminals of the radio receiver or broadcast relay and distributer 29 which may be of any known or other suitable type of radio receiver capable of furnishing the busses 27-28 with audio signaling currents of sufficient strength to supply the input circuits of the several subscribers line tubes 37, it being understood that several such line tubes (not shown) are supplied from the common busses as indicated by the multiple branch conductors 30.
  • a normally closed contact 31 on the relay 42 connects the common battery B to the conductor 32 which terminates in a normally open contact 33 in the jack 9 operable to extend the connection of conductor 32 to the signaling conductor 4 to supply battery potential thereto.
  • This signal conductor is arranged to be connected with battery upon energization of the subscribers line relay through the line relay contact 52, Fig. 1.
  • the relay 42, Fig. 2 also controls the connection of the multiple test circuit conductor 3 to the common battery B through a normally open contact 34 which comiection includes a special tone test device of any known or other suitable form, indicated diagrammatically at 35, operable to superpose a characteristic signal current on the test conductor 3.
  • a signal lamp 36 mounted near the jack 9 in the manner of the usual telephone line or call lamp.
  • . and 2 are shown connected to or terminating the description of Figs. 3 and 4 with which they are functionally related.
  • the circuits and apparatus shown in Figs. 1 and 2 are those of the main central station and one of its subscribers stations but it is to be noted that the other central stations served by the common district station are similarly equipped.
  • Fig. 5 wherein 38 indicates the district station, 91 the main central station (diagrammed in detail in Figs.
  • A the telephone and broadcast receiving apparatus, respectively, at a subscribers station connected with the central station 91, and 92 and 93 other central stations similar in all respects to station 91 except that the primary supervisor and supervising equipment are not situated thereat.
  • the radio relay apparatus indicated diagrammatically at 39 may be of any known or other suitable form operable to receive radio broadcast matter from one or more distant stations and relay the same to the several subscribers central distributing stations like that of Fig. 2.
  • These district stations are preferably also provided with means for originating broadcast matter, for example, a microphone 40 and modulator 41 connected with the relay apparatus.
  • a telephone trunk 101-102 connects the district station Fig. 3, with the central station Figs. 1 and 2, which trunk terminates in a jack 38 at the district station, Fig. 3, and in the usual line terminal apparatus 43 at the central station Fig. 1, which line terminal apparatus is the same in all respects as that of the subscriber A.
  • This terminal apparatus like that of the substation A is provided with multiple conductors 221, 222, 223 and a signaling conductor 224 corresponding in function to the conductors 1, 2, 3 and 4 respectively, of the substation A, leading to broadcast line terminal equipment not shown but similar in all respects to that shown in Fig. 1 associated with the line terminals of the substation A.
  • Other jacks 44 and 45 at the district station form the terminals of other telephone trunks 201-202 and 301-302 connecting with other central stations like that of Figs. 1 and 2.
  • Any of the lines 101-102, 201- 202, etc. may be connected with the supervisory telephone set 46 through the plug 47 and the respective line jacks 38, 44, etc.
  • Anv of the lines 101-102. etc. may be also operatively connected with the modulator 41 through the plug 48 and their associated line jacks 38, etc.
  • the said jacks are connected with multiple jacks 138, etc., and connecting cords or link circuits such as 49 provided for connecting one or more lines to either or both the modulator and telephone set.
  • the district station is connected with the broadcast distributing portion, (Fig. 2) of the central station through a pair of test circuits comprising a test trunk 150-151 and an order circuit 152- 153.
  • the test trunk is a simple normally disconnected two wire circuit terminating at both ends in simple jacks 50 and 51.
  • the order circuit 152-153 terminates at the dis- .trict station in a jack 7 2 and at the central station in a jack 73 and the usual common battery line terminal apparatus 54 with line lamp 55, the jacks 51, 73 and lamp 54 being located before an operator at the central station equipped with means for communicating with an operator at the district station which means may he an ordinary common battery cord circuit indicated symbolically at 56 (Fig.
  • test trunks and order circuits 161-162, 163-161, etc. extend from the district station to other central stations equipped like that of Figs. 1 and 2, said trunks and order circuits terminating at the district station in jacks 81, 83, etc. situated with the acks 5'0, 72, before the test opera-tor and accessible to the plug 80.
  • the central oiiice may be provided with a duplicate relay apparatus 89 arranged to be connected to the busses 27-28 by closure of a switch 70 when the apparatus 29 is disconnected by opening the switch 71, for test purposes.
  • Fig. 1 the circuits and apparatus used by the primary supervisor or wire chief at the main central station.
  • This equipment hereinafter termed the primary wire chiefs equipment or position is indicated generally in Figs. 1 and 5 by the reference numeral 97.
  • It comprises testing and supervisory apparatus like that of Fig. 3, that is, a telephone listening set 7 1 and a set of testing apparatus 98 both adapted to be connected through their respective plug terminals 99 and 100, respectively, with the jacks 75, 77, 103, etc. forming the terminals of trunks and lines leading to the several different central stations.
  • the jacks 7 5 and 76 form the terminals of a pair of test trunks 78 and 79 leading to the broadcast distributing section of the main central station, Fig.
  • test trunks 78,79 Associated with these test trunks 78,79 is a telephone line or order circuit 84 terminating at the wire chiefs position (Fig. 1) in the jacks 77 located adjacent to the jacks 7 5 and 76, and terminating at the main exchange in the usual common battery line terminal apparatus 111, the jacks 112 and calling lamp 113 of which is situated near the jacks 109 and 110 before the secondary wire chief.
  • Other groups of jacks 103 to 105 and 106 to 108 form the terminals of groups of trunks and telephone circuits 11d and 115, similar to the group 78 to 84, leading to the other central stations 92 and 93. (Fig. 5).
  • the secondary wire chief is provided with a suitable telephone answering, calling and interconnecting device preferably in the form of an ordinary common battery, operators cord circuit indicated at 87, and other more simple connecting links or dummy cord circuits and 86 for effecting connections between the jacks 109, 110 and 112 and the jacks 88, 91 and 95.
  • the jack 88 is a multiple jack for the subscribers line 09-78, being permanently connected thereto through line multiples 1-2 and conductors 116-117.
  • the jack 94 forms an extension of the input terminals of the subscribers line tube 37 through conductors 118-119, and the jack forms the terminals of an order circuit 120-121, terminating at the telephone operators switchboard (Fig. 1) in a.
  • the secondary wire chief at the central station may make various connections between the trunks 78-79 and telephone line 84 and the circuits of the central station in response to instructions received over the line 81 from the primary wire chief.
  • the order circuit 120- 121 As the purpose of the order circuit 120- 121 is to enable the secondary wire chief to extend the primary wire chiefs order circuit line 84: to the jack 122 at the telephone operators position, this jack may form the terminal of a line or trunk leading directly from the primary wire chief's position. This would be desirable at least for the main central station because of the chief operators nearness.
  • the district station 96 is operatively associated with the several groups of subscribers central stations 91, 92 and 93 through both radio and wire channels as indicated by the antenna symbols and connecting lines.
  • the district station 96 is arranged to receive broadcast matter from any distant station and relay the same by radio to the several subscribers central stations as indicated by the arrows adjacent to the antenna symbols on the several stations.
  • the station 91 represents the main central station diagrammed in detail in Figs. 1 and 2, while the subscribers substation AA is the one similarly designated in Figs. 1 and 2.
  • broadcast matter is transmitted from the district station (Fig. 3) by radio to the relay apparatus at the difi'erent central stations such as the relay and distributor 29 (Fig. 2), the audio output circuit of which is connected through switch 71 to the busses 2728.
  • a subscriber at substation A desiring broadcast service now connects his broadcast receiving or extension set A to the line by inserting the receiver plug P in the jack J which connects his receiver 64 across the line multiples 5 and 6 through the booster coil windings 60-65 and condenser 66 in series, and closes a path for direct current between the multiples 5 and 6 through coil 60, lower spring of jack J transmitter 62 and signaling key 63.
  • this relay is energized and closes the circuit of the cut-off relay L (Fig. 1), over a path which may be traced from the common battery B (Fig. 2) through the circuit elements 35, 3-1, 3, (into Fig. 1), cut-ofl relay L, 68, and through ground back to common battery B.
  • Energization of the cut-off relay disconnects the subscribers line from the telephone line signal apparatus in the usual manner, thus causing the line lamp L to become deenergized and extinguishing both signal lamps L and 36.
  • the cut-off relay is held energized over the test conductor 3 by battery supplied thereto through the special tone test device 35, a telephone operator in testing the line will receive this characteristic tone test instead of the usual click in the ear indicating that the subscribers line is busy with the special or broacast service which may or may not be interrupted for telephone service according to the wishes of the subscriber.
  • Euergization of the relay 42 (Fig. 2) also connects the input circuit of the subscribers line tube 37 to the broadcast busses 27-28 by way of contacts 23, 2 1 and conductors 25, 26, respectively.
  • relay 42 also energizes the sub scribers line lamp 37 by closure of its filament circuits through contact 351, and filament battery F.
  • the plate circuitof the tube 37 is energized from battery B through the plate circuit conductors 21, 22. and repeating coil windings 17 and 18.
  • the broadcast matter supplied to the input circuit of the tube 37 from the busses 27-28 is amplified in the output circuit 22, 18, B 17, 21, and transferred into the subscribers line circuit by the repeating coil windings 15-16 included in the line circuit.
  • the broadcast signal currents passing through the winding of the booster coil 61 are repeated in the coil 65 and included in circuit with the subscribers broadcast telephone receiver 64 which circuit may be traced from the coil 65 through circuit elements J P 64, P, J 89, 62, 63, 266, back to coil 65.
  • the plug P (Fig. 2) is pulled which opens the line circuit at the jack 9 deenergizing the relay 42, which in turn connects the battery to the signal circuit conductor 4 through relay contact 31 and energizes the radio service signal lamp 36 over a circuit which may be traced from common battery B through circuit elements 31, 32, 33, 4, 36 to ground and back to common battery B.
  • This causes the lamp 36 to glow steadily indicating to the broadcast service operator that a disconnection is desired whereupon the operator pulls the plug 10 which opens all the contacts of jack 9 and restores the circuits to normal.
  • microphone 40 When it is desired to originate broadcast matter at the district station (Fig. ,3), microphone 40 is used which operates through a modulator and transmitting portion of the radio relay 39, the circuits and apparatus of which modulator and transmitting portion of the relay being of any known or other suitable type.
  • a subscriber to broadcast from his substation he may be connected through the ordinary telephone exchange circuit (Fig. 1) to the telephone line circuit 101-102 terminating in the multiple jacks 38 and 138 at the district station (Fig. 3) from which the connection may be extended by plug 48 to the modulator of the relay transmitter 39.
  • the listening set 46 may be connected to the line through the plug 47 and the remaining one of the multiple jacks 38 and 138.
  • a test of the quality of reception at the central station may be had from the district station (Fig. 3) over the testing trunk 150-151 through the jack and the plug connection 50 and 47, and the listening set 46, the testing trunk having been connected with the output of the receiver 29 (Fig. 2) through jacks 51 and 72, and the line circuit 57. If it is desired that this test he made on the output of the receiver 29 free of all subscribers line connections, a duplicate relay transmitting apparatus 89 may be put into service and connected to the distributing busses by closure of swltch 7 0 before opening the switch 71 to clear the apparatus 29, thus preventing interruption of the broadcast service.
  • the primary wire chief makes use of his telephone set 74 to communicate his wants over one of the order circuits 84, etc. to the secondary wire chief at the particular central station whose circuits he desires to test, which testing, if in the nature of supervision of the quality of reception by the subscriber, may be made by the use of the telephone set 74, and if made for determining various conditions of the circuits, the testing apparatus 98 is used which may comprise any known or other suitable arrangement of testing apparatus and circuits such as a source of current, ammeter, voltmeter, etc.
  • the primary wire chief should the primary wire chief desire to test the conductor and opera tion of the subscribers line tube 37 (Fig. 2) independently of its connection with the dis tributing busses 2728, he should connect his telephone set 74 with the order circuit 84 through the plug and jack 99-77 and call the secondary wire chief at the central station through signal lamp 113 in the usual manner of making a telephone call, whereupon the secondary wire chief would establish connection through the answering plug of the cord circuit apparatus 87 and jack 112. The primary wire chief would then order a connection between the trunk 7 8 and jack 88, and trunk 79 and jack 94 through the link circuits 85 and 86 respectively, and instruct the local wire chief to open the switch 124.
  • the primary wire chief would then connect his testing apparatus 98 with the input circuit of the subscribers line tube 37, through plug and jack 10076, trunk 79, (into Fig. 2) plug and jack connections 1108694, and extension conductors 118- 119, and connect his telephone set 74 through plug and jack connection 99-75, trunk 78, (into Fig. 2) plug and jack connections 1098588, and extension conductors 116- 117 to the subscribers line multiples 12 which connect with the output circuit of the subscribers tube set through the connections of jack 9.
  • the wire chief at the position 97 would then be able to supply the input circuit of the subscribers tube with various forms of current and detect the resultant effects on the line multiples 12 through his telephone set 74 or other apparatus accord ing to the nature of the test.
  • Vhile I have herein described and illus trated the use of audio frequencies for distribution to the subscribers over their wired circuits the invention is not limited to such frequencies, but may employ also superaudio frequencies, so long as they are suitable for line transmission. I11 the work hereinbefore done by Major General Squicr and others, frequencies ranging from 25 to 100 kilocycles per second have been found suitable for this purpose. In order to make such frequencies available for distribution among the subscribers in the present system, the connections from the central station receiving and relaying distributing apparatus remain practically the same, as that described and shown in Fig. 2, the input or grid circuit of the individual line tube 37 also remaining the same.
  • the repeating coil connection to each line must either be supplemented or replaced however by a filter connection, preferably permanent, which will permit super-audio frequency currents to be transmitted from the plate circuit of the tube to and over the line circuit to the subscribers station, while the battery current from the battery B will simultaneously flow over the subscribers line for signaling and talking purposes of the subscriber.
  • a filter connection preferably permanent
  • the battery current from the battery B will simultaneously flow over the subscribers line for signaling and talking purposes of the subscriber.
  • complementary connections must be made, and a detector radio set must be connected to receive superaudio currents over the line, while the telephone elements are connected, preferably in parallel, to receive the battery current and transmit and receive audio frequency waves.
  • a district broadcast service station a plurality of central stations each with subscribers substations and wire lines interconnecting them, radio broadcast transmitting means at the district station, distributing relay means at each central station for relaying the matter broadcasted from the district station onto the subscribers wire lines at a frequency suitable for line transmission, and means for supervising and testing the circults and apparatus of all said central stations and their subscribers stations from a common point.
  • a district broadcast service station a plurality of central stations each with subscribers substations and wire lines interconnecting them, radio broadcast transmitting means at the district station, distributing relay means at each central station for relaying the matter broadcasted from the district station onto distributing busses at a frequency suitable for line transmission, subscribers relay means at the central station individual to each subscriber-s line for connecting the line with the busses, and means for supervising the operation of the said relay means at the different stations from a common point.
  • a district broadcast service station a plurality of central stations each with subscribers substations and wire lines interconnecting them, radio broadcast transmitting means at the district station, distributing relay means at each central station for relaying the matter broadcasted from the district station onto distributing busses at a frequency suitable for line transmission, subscribers' relay means at the central station for individually connecting a subscribers line with the busses, radio wire chiefs supervisory and testing circuits extending between the district station and the central stations with switching means at the central stations for connecting said circuits with the distributing relay means, wire chiefs supervisory and testing circuits extending from a common point to switching points in said central stations, and means at the switching points for connecting the Wire chiefs circuit to different parts of the different subscribers relay means.
  • a district broadcast service station a plurality of central stations having radio receiving means, a plurality of subscribers served by each central station through receiving means individual to each subscriber, means for supervising the several central station receiving means from a common point and means for supervising the subscribers receiving means from a common point.
  • a district radio distributing station In a system of radio broadcast distribution, a district radio distributing station, a plurality of Wire line distributing stations, trunk circuits connecting said district radio distributing station with each of said wire line distributing stations, and trunk lines connecting one of said wire line distributingv stations with each of the other of said wire line distributing stations.
  • a district radio broadcast distributing station a plurality of groups of subscribers stations, a central station for each group having relay means establishing communication between said district station and its group of subscribers stations said relay means having parts common to the group and parts individual to each subscribers station in the group, means for supervising said common part at each central station from a common point and means for supervising said individual parts at all saidcentral stations from a common point.
  • a plurality of groups of subscribers stations a central station for each group, radio receiving means at each central station, individual line relays adapted to receive the output of said radio receiving means and relay it into their respective lines, and means controlled from a common point for effecting and testing a supervisory connection with either the input or output side of each of said individual line relays.
  • a telephone central station a plurality of subscribers stations connected therewith by wired line circuits, radio receiving appara tus at said central station terminal output bus for said receiving apparatus, and individual vacuum tube line relays, each with its input side adapted for connection with said bus, and its output side to its line, together with a wire chiefs position equipped with listening and testing apparatus, and means for connecting the same to either the input or the output side of any of said tubes.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
  • Mobile Radio Communication Systems (AREA)
US9355A 1925-02-14 1925-02-14 Trunking system of radio distribution Expired - Lifetime US1580409A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US9355A US1580409A (en) 1925-02-14 1925-02-14 Trunking system of radio distribution
GB3240/26A GB247550A (en) 1925-02-14 1926-02-04 Trunking system of radio distribution
FR613000D FR613000A (fr) 1925-02-14 1926-02-10 Système de distribution radiotéléphonique
DEC37842D DE567672C (de) 1925-02-14 1926-02-10 Schaltungsanordnung zur Verbreitung von Rundfunkdarbietungen ueber Fernsprechanlagen
CH122696D CH122696A (de) 1925-02-14 1926-02-12 Anlage zur Verbreitung von Rundfunk.
BE332313D BE332313A (de) 1925-02-14 1926-02-13

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US9355A US1580409A (en) 1925-02-14 1925-02-14 Trunking system of radio distribution

Publications (1)

Publication Number Publication Date
US1580409A true US1580409A (en) 1926-04-13

Family

ID=21737132

Family Applications (1)

Application Number Title Priority Date Filing Date
US9355A Expired - Lifetime US1580409A (en) 1925-02-14 1925-02-14 Trunking system of radio distribution

Country Status (6)

Country Link
US (1) US1580409A (de)
BE (1) BE332313A (de)
CH (1) CH122696A (de)
DE (1) DE567672C (de)
FR (1) FR613000A (de)
GB (1) GB247550A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3521168A (en) * 1966-03-09 1970-07-21 Edward F Kaiser National warning system operable from central station

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3521168A (en) * 1966-03-09 1970-07-21 Edward F Kaiser National warning system operable from central station

Also Published As

Publication number Publication date
CH122696A (de) 1927-10-01
GB247550A (en) 1927-05-04
FR613000A (fr) 1926-11-05
BE332313A (de) 1926-03-31
DE567672C (de) 1933-01-09

Similar Documents

Publication Publication Date Title
US1688453A (en) Telephone signaling system
US1580409A (en) Trunking system of radio distribution
GB1336931A (en) Communication systems
US1568938A (en) System of radio broadcast distribution
US2247507A (en) Telephone system
US1577108A (en) Trunking system of radiodistribution
US1706378A (en) Trunking system for radiodistribution
US1592646A (en) Automatic telephone system
US2189994A (en) Telephone system
USRE16231E (en) clement
Abraham et al. Crossbar toll switching system
US1577107A (en) Radiophone system
US1687883A (en) Transmission system
US2017644A (en) Service observation system
US2375136A (en) Telephone system
US2306701A (en) Combined telephone and telegraph cord and attendants' circuits
US1635151A (en) Radio distributing system
US1805446A (en) Radio broadcasting system
US1635155A (en) Radio service metering system
US2024592A (en) Telephone system
US1576309A (en) Broadcasting system
USRE17069E (en) clement
US1664468A (en) Program-selecting circuits
US1695182A (en) Trunking system for radio distribution
US1381545A (en) Repeater-controlling system for pour-wire telephone-circuits