US2152010A - Station selection - Google Patents

Station selection Download PDF

Info

Publication number
US2152010A
US2152010A US117533A US11753336A US2152010A US 2152010 A US2152010 A US 2152010A US 117533 A US117533 A US 117533A US 11753336 A US11753336 A US 11753336A US 2152010 A US2152010 A US 2152010A
Authority
US
United States
Prior art keywords
station
stations
signal
code
relay
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
US117533A
Other languages
English (en)
Inventor
Walter J Zenner
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.)
AT&T Teletype Corp
Original Assignee
Teletype Corp
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 Teletype Corp filed Critical Teletype Corp
Priority to US117533A priority Critical patent/US2152010A/en
Priority to GB27379/37A priority patent/GB489531A/en
Priority to FR830678D priority patent/FR830678A/fr
Application granted granted Critical
Publication of US2152010A publication Critical patent/US2152010A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks

Definitions

  • the present invention pertains to telegraphic communication systems and more particularly to telegraph systems involving a plurality of stations arranged with instrumentalities for their selective interconnection for telegraphic communication.
  • An object of the invention is the provision of simple and reliable circuits and mechanisms to enable any station of a telegraph system to select another station or a group of stations with which it is desired to communicate.
  • An object also is to provide a system of answerback communication such that when a station has responded to its calling code signal, a response signal or answer-back signal comprising character-code signals will be transmitted automatically over the interconnecting line circuit.
  • a further object is to enable the originating station after selecting tions to establish a condition by which all other 20 stations of the system are prevented from interrupting the established communication, except that a preferred station may be equipped to monitor a message and to interrupt transmission of the message if desired.
  • Fig. 1 shows a line circuit and circuits of three sub-stations
  • Fig. 2 shows a detail of keyboard operating 5 mechanism utilized in the answer-back system
  • Fig. 3 shows a detail of selector mechanism utilized in station selection and associated control functions.
  • a common operating bail I extends across all of the key levers 2 of a telegraphic transmitting keyboard, at a sufiicient height above the key levers to approach them but not to engage them.
  • a striker 4 is clamped having a lugtherepn in position to be engaged by bail l when it" is rotated upon its axis 5 in response to energizing of an answer-back magnet 6, thus effecting mechanical operation of a predetermined key lever.
  • code signal member II is tensioned by spring l2 and is restrained by an operating bail l3.
  • Six rocking vanes M are positioned to obstruct the rotation of member ll upon its pivot [5 when any vane is in as determined by the location of notches in the code-signal member II.
  • An electrical contact spring I6 is moved by member II when operated, and a switching function is performed among contacts of spring l6 and contacts of its asso- 50 ciated fixed contact members l1.
  • each station equipment there areincluded two manual keys l8 and IQ of dashpot type adjusted for different time periods in operation.
  • depression of the operating knob trans 55 In Fig. 3 an operating other than its code-signal position mits mechanical energy through the electrical contact members to the plunger of the dashpot and moves the plunger accordingly while retaining closed the electrical circuit of the key.
  • the upper contact member Upon manual release of the key, the upper contact member returns at once to mechanical normalcy thus opening the electrical the lower member of the key begins its return movement, restrained by the dashpot, and subsequently closes the electrical circuit of the key after a time period .determined by preliminary adjustment of the dashpot elements.
  • Key I8 is adjusted to hold line circuit 3
  • each station equipment four code-signal members such as H are provided to operate're spectively four sets of contact springs in the man.- ner of contacts I6 and I1, Fig. 3, and as described in Patent 1,904,164, cited, illustrated at 2
  • extends in series through stations A, C, and E, the letter identifying the station serving also to identify the calling code-signal in response to which the station may be qualified for communication.
  • passes through a keyboard transmitter 32, a line relay 34 which may be either polar or neutral, and a pair of associated manually operable break keys I8 and I9.
  • Station equipment responsive to the line relay 34 includes printer magnet 35 symbolizing a complete telegraphic printing equipment for operating printing types to record received bode signals and also eiiective by means of a plurality of apparatus as illustrated in. Fig. 3 to operate contact devices 2
  • the controlling codesignals are variant for the several stations respectively and constitute the variant calling signals for the several stations individually.
  • Contact devices 22 are responsive through code members alike at all stations forming a group of stations which are to be called jointly as a group by a single code signal. Such a group may include all stations of a system.
  • Contact devices 23 are controlled by code members alike at all sta tions andare responsive to a stop code signal Z, while contact devices 24 are controlled'by other code members alike at all stations and are responsive to a lookout code signal Y.
  • line relay 34 There are also controlled by line relay 34 and by the contact members 2
  • each station There is also at each station the answer-back magnet 6 with armature pivoted at and connected mechanically to the keyboard ball I and there is provided at eachstation a single striker 4 upon a key lever 3 of the keyboard transmitter 32, the striker 4 being fixed upon variant key levers at the several stations preferably as folcircuit of the key and "break sig-' lows: At station A upon key lever B, at station 0 upon key lever D, at station E upon key lever F, and so on, the alphabet being exhausted when 12 stations have been designated alphabetically, reserving Y and Z for lockout and stop conditions as noted above. Optionally, fewer or a single character-code signal may be utilized for answering, thus amplifying the directory possibilities of the alphabet to accommodate a greater number of stations.
  • a manual key 48 is connected to grounded battery and to motor 4
  • An operator at station A first operates the motor controlskey Hi. This deenergizes all line relays 34 and eifects release of armatures of all slow-to-release relays 36 at all stations with resultant energization of motor control relays 31 at all stations, each relay 31 through its righthand-armature setting up its own holding circuit through contacts of devices 24 and 23 to grounded battery 40, and each relay 3'! through its lefthand armature also sett' g up the condition of starting and continuing operation of all motors 4
  • the printing telegraph receivers of which magnet 35 constitutes a part are now in condition to receive message signals. Automatic reclosing of key l9 reenergizes all relays 36.
  • the operator at station A next transmits by keyboard transmitter 32 the call letter A for such station which operates contact device 2
  • the call-responsive relay 38 thereat is energized through its righthand winding and forms its holding circuit through its left-hand winding, its own contact and grounded battery 44.
  • Answer-back magnet 6 at station A also is energized momentarily overa circuit through left armature and back contact of relay 39 and contact device 2
  • Magnet 6 attracts its armature momentarily and the bail I through striker 4 depresses the key lever 3 momentarily with the same effect as manually striking the key B.
  • the keyboard transmitter 32 transmits the code signal B upon the line 3
  • Atxall stations relay 39 is energized over an obvious circuit through the upper contact of device 24 and forms its holding circuit through contacts of relay 36 to grounded battery 44.
  • the holding circuit described above for relay 3'! at non-qualified station E is broken by contact device 24, the relay is deenergized and releases its armature to stop its motor M and to extinguish its white lamp 42.
  • energized busy relays 39 also illuminate the red busy lamps 43 at all stations whether a station has been selected or excluded.
  • the code signals may be selected variantly; for instance, code signal for word space or line feed may be substituted for Y above and carriage return for Z below, and have some advantages.
  • the recording surface ,of the telegraphic printer the record ABCDY'indicating that sta tion A has been calling, that station C has been called and has responded, and that all other stations have been excluded.
  • the white lamp and the red lamp are glowing at each qualified station while the red lampalone is glowing at all excluded stations.
  • the excludedstations thus are provided with knowledge of the identity of the stations which are using the line circuit 3
  • Favored stations or monitor stations have a further supervisory function as illustrated at station A which may be exercised by operation of manual key 48.
  • may close key 48 at such station, thereby energizing the motor 4
  • the operator at the excluded monitor station now may judge of the relative importance of the proposed message over the probable importance of the message being currently transmitted between or among the prior communicating stations and which now is being recorded at the conditionally qualified monitor station and if the operator so which operates at above in connection with illustration desires may interrupt the instant communication by operating key l9 to restart all stopped motors and then may set up any desired connection.
  • the object of break key I8 is to enable-- any duly qualified communicating station. or monitor station to interrupt operation of the line circuit long enough, to indicate a request to the then transmitting station to desist from transmission, but not long enough to releasethe armature of any relay 36.
  • I 10 Assuming that the communication as set up above between stations A and C is not interrupted, then at the close of the communication period'either station A or C may operate the motor controlkey i9 which will deenergize and release all slow-to-release relays 36 at all sta-- tions and will interrupt the holding circuits of all operated relays 38 and 39 at all stations. Release of relay 39, will interrupt the energizing circuits of all busy signal lamps 43.
  • Deenergization of relays 36 at excluded stations will reenergize motor control relays 3i and will restart motors M at those stations. Accordingly, all motors will be operating at all stations.
  • the operator then may transmit a stop code signal Z which will print Z at all stations, operate contact device 23 at all stations to interrupt the holding circuit of motor'control-relay 311 at all stations'thus stopping all motors, extinguishing all white lamps 42, and restoring allapparatus to its normal condition of idleness and readiness for further service.
  • the method of operating a telegraphic answer-back system for a telepgraph system wherein a plurality of stations are connected to a single line circuit which comprises, assigning calling signals variant for every station of the system whicl'i connect the station to the signaling circuit, assigning answer-back signals variant for every station, and transmitting from every station in response to receipt of the calling signal of that station, the answer-back signal of that station which is variant from every calling signal.
  • the method of operating a telegraphic system which comprises, transmitting calling code signals for each station to be connected, transmitting answer-back code signals from each called station, the number of called stations being less than the total number of stations, transmitting a code signal indicating disconnection, and recording all said code signals at all stations.
  • Mechanism for operating an answer-back system in which the answer-back signal is a code signal to be transmitted in response to operation of a single key lever of a telegraphic keyboard transmitter comprising a telegraph station, a keyboard transmitter, a key lever in said keyboard ,transmitter, an answer-back magnet and arma ture, said armature positioned to engage and operate said key lever in response to energization of said magnet, and means to energize said magnet in response to receipt of a predetermined calling code signal which identifies said station.
  • Mechanism for operating an answer-back system comprising a station, a keyboard transmit-- ter at said station, a key lever in said transmitter to control said transmiter to transmit an answerback signal, a magnet and armature, means integrallynnited with said armature to engage and operate said key lever when said armature is operated, and-means responsive to a received calling code signal identifying said station for operating said magnet.
  • a plurality of telegraphic stations means at each station to transmit an answer-back message in response to receipt of code signals representing the calling signals of the station, and means at each station responsive to a received code signal to render said answer-back means non-responsive.
  • means to establish in said system means to establish in said system a station selecting and answer-back condition means to transmit an answer-back message in response to a selection of a station, and means to terminate said station selection and answer-back condition.
  • a plurality ,of telegraphic stations means at each of said stations to transmit an answer-back message upon seizure of the station for communication, and means at each station reirom the calling signal of sponsive to a received code signal to render said answer-back means, non-responsive.
  • a motor a control relay for said motor, a line circuit, a key having contacts in said line circuit to which contacts said control relay is responsive, a shunt for said contacts of said key to render said contacts ineffective, a relay having contacts included in said shunt to close said shunt, and a'call-responsive relay having contacts included in said shunt to open said shunt.
  • a telegraphic recording and transmitting equipment included in said line circuit, a motor mechanically associated with said telegraphic equipment, remotely controlled means eifective through said line circuit for energizing and deenergizing said motor and for shunting said transmitting equipment, and wholly local means for energizing and deenergiz'ing said motor and for removing the shunt of said transmitting equipment.
  • a telegraphic line circuit a plurality-of telegraphic recording and transmitting equipments included in said line circuit, a plurality of motors one mechanically associated with each of said telegraphic equipments, remotely controllable starting and stop ping means for each of said motors, a plurality of keys, one at each of said telegraphic equipments for remotely controlling said starting and stopping means, remotely controllable means for disabling a desired one of said keys, and wholly local means associated with one of said equipments and with said disabled one of said keys for starting said motor associated with said disabled one of said keys.
  • a line a plurality of motor driven printing telegraph equipments on said line responsive to permutation code signals of equal length and having normally inert motors, and first automatic key manually operable to transmit on said line a prolonged non-permutation signal longer than one of said permutation code signals, a second automatic key manually operable to transmit on said line a more greatly prolonged non-permutation code signal, and motor controlling'means responsive to said more greatly prolonged signaJ, said printing telegraph equipment being unresponsive selectively to said prolonged non-permutation signal because it is too long and said motor controlling means being unresponsive to said prolonged non-permutation signal because it is too short.
  • a line circuit a plurality of stations on said line circuit, printing telegraphic receivers one at each station each including a motor driven selector with driving motor therefor normally inert, means responsive to a non-permutation motor-control signal of a predetermined minimum duration over said line circuit Iorstarting said motors at all stations, means responsive to permutation code signals of uniform duration for operating said receiver, and a mechanically regulated manually operable break key for transmitting a non-permutation break signal of predetermined duration longer than one of said permutation code signals and shorter than said non-permutation motor-control signal.
  • normally inert motors and motor control relays one at each station, means to energize all said relays to start all said motors and to continue each of said motors operating while its associated relay remains energized, means for deeneigizing all of said relays, and call-responsive means one at each station responsive to predetermined variant calling code signals one for each station, each i said call-responsive means adapted to condition at each station for said relays,
  • ated relay remains energized,'holding circuits one means to interrupt all said holding, circuits, and means one at each station responsive to a predetermined code signal and each adapted to form a further holding circuit for the associated one ofsaid relays.
  • a recording receiver a motor driven permutation selector included inv said receiver having a nor-. mally inert motor, a motor/control relay controlling said motor to operate while saidrelay re- 1 mains energized, remotely controlled means for ablingall said "ing a station for communication,
  • a line a plurality of stations connected to. said line, permutation code selectors one at each' of said stations, means responsive to said selectors when operating in response to permutation code signals for selecting a station for communication, means responsive to said selectors when operating in response to permutation code signals for disfirst mentioned means, means responsive to said selectors when operating in response to permutation code signals for restoring said station to normal condition, and means for recording at all stations all of said permutation code signals above mentioned.
  • a line a plurality of stations connected to said line, permutation code selectors one at each of 'said stations, means operable by said selectors in response to permutation code signals for selectmeans responsive to said selectors for transmitting an answerback permutation code signal, means responsive to said selectors for disabling said station selecting equipment, means operable by said selectors in response to permutation code signals for restoring all apparatus to normal, and means operable by said selectors for recording at all stations all of said permutation code signals.
  • a telegraph line circult normally in non-communicative condition, a plurality of telegraph apparatus sets associated with ,said circuit andnormally inoperative, selective means to'render said sets individually operative, means to render said line circuit in com- .municative condition, a system of visual signals at one of said stations, means to display a signal in .said system when said line circuit is in communicative condition, and means to display a dii-,
  • the method of operating a telegraphic system including a single channel of communication and a plurality of stations thereon which comprises, transmitting over said channel to each station calling code signals for each, station, transmitting answer-back code signals from each called station, transmitting a change-over code tionv of a single nication terminating code signal, and recording all said code signals at one station.
  • the method of operating a telegraphic system including a single. channel of communication and a plurality of stations thereon which comprises, transmitting calling code signals for each station to be connected telegraphically to -said channel, transmitting answer-back code signals from each called station, transmitting a code ,signal indicating disconnection, and recording all said code signals at one stations 24.
  • Mechanism for operating an answer-back system in which the answer-back signal is a code signal to be transmitted in response to operakey lever of a telegraphic keyboard transmitter, a telegraphic station including a keyboard transmitter, a key lever in said keyboard transmitter, an answer-back magnetand armature, mechanical means integral with said armature and tegral with said keyboard key lever, said mechanical means and said further mechanical means mutually engageable for operating said key lever in response to energization of said mag-, net, and means to seize a station for communication and to, energize said magnet in response to seizure of said telegraphic station for communication.
  • Mechanism for operating an answer-back system comprising a telegraphic station, a keyboard transmitter at said station, a key lever in said transmitter transmit an answer-back signal, a magnet and armature, said armature positioned to mechanically engage said key lever when operated, and means for operating said armature upon seizure of said station for communication.
  • a motor control system a telegraph line circuit, a telegraphic-reeording selector included in said line circuit, a motor mechanically associated with said telegraphic selector, remotely controlled means effective through said line circuit for energizing said motor, remotely controlled means eflective through said selector for deenergizing said motor, and wholly local means for energizing and deenerglzing said motor.
  • a line a plurality of stations connected to said line, permutation code selectors one at each 0! said stations, means operable by said selectors in response to permutation code signals for selecting a station for communication, means operative upon station selection for transmitting an answer-back permutation code signal, means responsive to said selectors for disabling said station selecting equipment, means operable by said selectors in response to permutation code signals for restoring all apparatus to normal, and means operable by said selectors for recording at all stations all of said permutation code signals.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Selective Calling Equipment (AREA)
US117533A 1936-12-24 1936-12-24 Station selection Expired - Lifetime US2152010A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US117533A US2152010A (en) 1936-12-24 1936-12-24 Station selection
GB27379/37A GB489531A (en) 1936-12-24 1937-10-08 Improvements in or relating to station selection in a telegraphic communication system
FR830678D FR830678A (fr) 1936-12-24 1937-12-11 Appareils télégraphiques imprimeurs et analogues

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US117533A US2152010A (en) 1936-12-24 1936-12-24 Station selection

Publications (1)

Publication Number Publication Date
US2152010A true US2152010A (en) 1939-03-28

Family

ID=22373437

Family Applications (1)

Application Number Title Priority Date Filing Date
US117533A Expired - Lifetime US2152010A (en) 1936-12-24 1936-12-24 Station selection

Country Status (3)

Country Link
US (1) US2152010A (fr)
FR (1) FR830678A (fr)
GB (1) GB489531A (fr)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2416699A (en) * 1942-12-08 1947-03-04 Rita Smith Kinkead Station selector system
US2455724A (en) * 1940-08-17 1948-12-07 Bell Telephone Labor Inc Control of selectors over communication channels by storage controlled transmitters
US2459904A (en) * 1943-12-09 1949-01-25 Bell Telephone Labor Inc Telegraph signal code translator
US2495452A (en) * 1946-11-18 1950-01-24 Mobile Comm Company Communication system
US2495682A (en) * 1938-12-30 1950-01-31 Bell Telephone Labor Inc Communication system
US2543174A (en) * 1948-08-13 1951-02-27 Teletype Corp Telegraphically controlled timing mechanism
US2739180A (en) * 1952-10-21 1956-03-20 American Telephone & Telegraph Message address intercommunicating telegraph system
US2838749A (en) * 1954-06-14 1958-06-10 Sperti Faraday Inc In-and-out register and paging system
US2845478A (en) * 1954-02-12 1958-07-29 American Telephone & Telegraph Selective station calling system
US2874210A (en) * 1954-04-23 1959-02-17 Teletype Corp Automatic telegraph station selector
US2907980A (en) * 1953-06-05 1959-10-06 Gen Railway Signal Co Multiple station code communication system
US2907981A (en) * 1953-06-05 1959-10-06 Gen Railway Signal Co Code communication system
US2942250A (en) * 1956-11-15 1960-06-21 Hupp Corp Universal coder
US2944247A (en) * 1955-03-23 1960-07-05 North Electric Co Supervisory control system
US2965881A (en) * 1956-05-28 1960-12-20 Westinghouse Electric Corp Supervisory control systems
US3141928A (en) * 1955-11-28 1964-07-21 Bell Telephone Labor Inc Discrete address time division multiplex data transmission system
US3244805A (en) * 1961-06-29 1966-04-05 Ibm Counter controlled remote station transmission to central data collecting station
US3245038A (en) * 1961-06-30 1966-04-05 Ibm Central to remote communication system with address modification for the remote stations
US3244804A (en) * 1961-06-28 1966-04-05 Ibm Time delay controlled remote station transmission to central data collecting station

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2419799A (en) * 1943-08-06 1947-04-29 Teletype Corp Receiver transmitter

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2495682A (en) * 1938-12-30 1950-01-31 Bell Telephone Labor Inc Communication system
US2455724A (en) * 1940-08-17 1948-12-07 Bell Telephone Labor Inc Control of selectors over communication channels by storage controlled transmitters
US2416699A (en) * 1942-12-08 1947-03-04 Rita Smith Kinkead Station selector system
US2459904A (en) * 1943-12-09 1949-01-25 Bell Telephone Labor Inc Telegraph signal code translator
US2495452A (en) * 1946-11-18 1950-01-24 Mobile Comm Company Communication system
US2543174A (en) * 1948-08-13 1951-02-27 Teletype Corp Telegraphically controlled timing mechanism
US2739180A (en) * 1952-10-21 1956-03-20 American Telephone & Telegraph Message address intercommunicating telegraph system
US2907980A (en) * 1953-06-05 1959-10-06 Gen Railway Signal Co Multiple station code communication system
US2907981A (en) * 1953-06-05 1959-10-06 Gen Railway Signal Co Code communication system
US2845478A (en) * 1954-02-12 1958-07-29 American Telephone & Telegraph Selective station calling system
US2874210A (en) * 1954-04-23 1959-02-17 Teletype Corp Automatic telegraph station selector
US2838749A (en) * 1954-06-14 1958-06-10 Sperti Faraday Inc In-and-out register and paging system
US2944247A (en) * 1955-03-23 1960-07-05 North Electric Co Supervisory control system
US3141928A (en) * 1955-11-28 1964-07-21 Bell Telephone Labor Inc Discrete address time division multiplex data transmission system
US2965881A (en) * 1956-05-28 1960-12-20 Westinghouse Electric Corp Supervisory control systems
US2942250A (en) * 1956-11-15 1960-06-21 Hupp Corp Universal coder
US3244804A (en) * 1961-06-28 1966-04-05 Ibm Time delay controlled remote station transmission to central data collecting station
US3244805A (en) * 1961-06-29 1966-04-05 Ibm Counter controlled remote station transmission to central data collecting station
US3245038A (en) * 1961-06-30 1966-04-05 Ibm Central to remote communication system with address modification for the remote stations

Also Published As

Publication number Publication date
FR830678A (fr) 1938-08-05
GB489531A (en) 1938-07-28

Similar Documents

Publication Publication Date Title
US2152010A (en) Station selection
US1943475A (en) System for selective calling of telegraph stations
US2279295A (en) Telegraph exchange system
US2455724A (en) Control of selectors over communication channels by storage controlled transmitters
US2148430A (en) Telegraph selection system
US2334876A (en) Printing telegraph system
US2599988A (en) Automatic telegraph switching
US2148435A (en) Station selector system
US2714626A (en) Private line intercommunicating teletypewriter system
US2211232A (en) Station selection by printer selector
US2351621A (en) Printing telegraph exchange system
US2979556A (en) Semiautomatic teletypewriter tape relay system
US2484838A (en) Telegraph exchange system
US2560266A (en) Communicating system
US2082924A (en) Printing telegraph system
US2268335A (en) Selective signaling system
US2387246A (en) Telegraph exchange system
US3251929A (en) Automatic line switching system
US2320997A (en) Communication system
US2416699A (en) Station selector system
US2836653A (en) Tape movement check in a telegraph system
US2419730A (en) Printing telegraph system having serially connected, step-by-step automatically selective stations
US2227121A (en) Printing telegraph system
US1910867A (en) Automatic concentration system
US2040691A (en) Selective code receiver