US1821758A - Signal and control system - Google Patents
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- US1821758A US1821758A US202451A US20245127A US1821758A US 1821758 A US1821758 A US 1821758A US 202451 A US202451 A US 202451A US 20245127 A US20245127 A US 20245127A US 1821758 A US1821758 A US 1821758A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B3/00—Line transmission systems
- H04B3/60—Systems for communication between relatively movable stations, e.g. for communication with lift
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- My invention relates ,to signal and Vcontrol Y systems and more particularly to such systems as applied to communication and con trol between different train units of a single train, or between different trains, or between a stationary pointl and a moving vehicle.V Still more particularly my invention is primarily concerned with signal and control systems for operation between a leading, or master locomotive of a train and other ⁇ oco motives of the same train. n
- One of the-purposes of my invention V.1s to provide means whereby the functioning of a number of locomotives may be controlled from a single master, or leading, locomotive of the train by means of high frequency cur ⁇ rents, such as are employed in the usual high frequency communication system.
- Am other purpose of my invention is to ⁇ provide means such that a single high frequency channel may be employed for comm-unication between different units, or different locomotives of a train and for control of either signal or power functions on the various units or locomotives,
- a further purpose is to provide means whereby these objects may be accomplished in a reliable and satisfactory manner and with a minimum of equipment.
- a high frequency communication system such as that employed either in radio communication o-r in connection with communication by means of carrier currents transmitted over the lines of the usual power distribution system.
- This equipment may likewise be located upon any part of the train, orV on a separate train or at any point where signal or power functions are to be controlled.
- the .equipment located upon the master locomotive A includes a transmitterl of high frequency current suoli as is employed in the usual radio or carrier current communication system. This transmitter is adapted to supply high frequency currents through the transformer 2 and appropriate cou ling circuit 3 to a suitable conductor 4 lea ing to the other locomotives of the train.
- the conductor 4 may comprise the usual trolley wire located above the train, or in the case of steam railways it may comprise the rails, or special Wires provided for the purpose either upon the train or located upon poles along ⁇ the track. If desired the conductor d may be replaced by suitable antennae located upon each of the various train units whereby the contemplated communication and control may be effected by space radio. Associated with the transformer 2, which may be of the usual three Winding type, is an appropriate.
- detector or demodulator 5 which is adapted to respond to received high frequency currents and to supply audio currentsto a receiver 6, or if desired, through audio amplifiers 7 to either a visible or audible signaling device S.
- the equipment of the locomotive B includes a transformer 1 Wl ich is adapted to supply high frequency currents through the output transformer 2 and coupling circuit 3 to, the conductor l for communication 'from unit B to unit A.
- a detector 5 which serves to demodulate the received high frequency Waves and supply audio currents to the telephone receiver 6 and through audio amplitiers 7 to the visible or audible signaling, ⁇ device 8.
- the devices 8 and 8 be used for calling purposes and 'may be adaptedto be disconnected from circuit when the operator lifts his receiver in response to a call.
- the system comprises substantially'the apparatus used in connection with the usual high frequency radio or carrier current communication system.
- a source of alternating current having frequencies which are variable Within the voice range and means whereby the outputfrom the transmitter 1 may be modulated by means of these currents having definite frequencies determined in accordance with the operation which is to be performed upon a remote train unit.
- an electron discharge device 9 having the usual oscillation circuit comprisingthe condensers 10and 11 which are connected in series between the anode and the grid of the ⁇ discharge device 9 and in parallel with an inductance 12 through a conductor 13, inductance 12, conductor 1li, upper movable contact of the relayA 15 and conductor 16.
- the primary Winding of the output transformer 17 Connected to this oscillatory circuit through the conductors 13 and 1G is the primary Winding of the output transformer 17, the secondary Winding of Which is connected to the modulatingl circuit 18 of the transmitter 1.
- a voicermodulating circuit including a source of direct current potential 19, a transmitter 20 and the lower movable contact of the relay 15.
- the oscillation generator 9 With the relay l5 in the position shown in the drawing the oscillation generator 9 is connected to supply currents having a frequency determined by the inductance 12 to 'the modulating circuit of the transmitter l. These currents, fora purpose later to beset forth, are highin the audio range and are frequency Which l term the base frequency of the oscillation ⁇ generator.
- 21 represents an inductance which is divided into sections and which is adapted to be connected in series with the inductance 12 by a circuit incliuiiiu,r conductor 11i, inductancc 21, control arm 23, conductor 2li, conductor 25, contact 26, upper movable contact of the relay 15, conductor 16, condensers 1l and 10 and conductor
- the arrangement is such that When the relay 15 is in its upper position the inductance 12 determines the frequency ofthe oscillation ⁇ generator, whereas with the relay 15 in the lower position the inductance 12 plus those sections of the inductance 21v between the conductor 14 and the movable arm 03 vdetermine the frequency of the. oscillation generator.
- the relay 15 is adapted to be operated respousively to adjustment of the control handle 23 upon the inductance 21 by meansof an energizing circuit includingr the control handle conductor 24, source of potential 27, aetiuiting coil ofthe rela-y 15, conductor 28, and one of the contacts 29.
- esseci; nd with the (uitput circuit of the unodulating deviav l is a telephone receiv- ",-aud through conductors and 3l, a
- 'ibis relay is deenerin its closed ation it connects a tuucd relays .Of-l. -l-l, 35, 3G, IS7, SS "h tho coingluctors il() and 31.
- i relays is' adapted to respond to c u. frefuuucv determined by the :7, 21 when the control handle 23 is as, for examuid, vwhen it is on the will respond, etc: X' 1 when rated to ne bridge nl source of 'on and details of 'lll'xe arm 4-1, l .ance 99 and ive lintents various positions by i pensive device lli mechanism. rn. be
- the com- 'biation with a high frequency transmitter of means for modulating the output from said transmitter With either voice currents or control currents, said voice current modulating means being inoperative during periods of control current modulation, and said control current having any one of a plurality of frequencies determined in accordance with the ulating the ouptut from said transmitter and means responsive to said control currents for controlling said operation.
- a transmitter of high frequency currents of means for modulating the output from said transmitter with voice currents means for modulating the output from said transmitter With control currents having any one of a plurality of frequencies determined in accordance with the operation to be controlled, means for rendering said voice modulating means inoperative during periods of control current modulation, demodulating means for said high frequency currents and means responsive to the frequency of said control currents for controlling said operation.
- a signal and control system the combination with a transmitter of high frequency currents, of means for modulating the output from said transmitter with voice currents, means for modulating the output from said transmitter with control currents the frequency of said cont-rol currents being Within the voice range and determined in accordance with the oseration to be controlled, means for rendering said voice modulating means inoperative during periods of control current modulation, demodulating means for said high frequency,currents, means respon sive ⁇ 'to the frequency of said control currents for controlling saidoperations, and means whereby said control current responsive means is rendered unresponsive to voice currents.
- a signal and controlsystem the combination with a high frequency transmitter, of means for alternately modulating the output from said transmitter with control currents having frequencies within the voice range and Wi yh currents of a base frequency ⁇ means for modulating the output from said transmitter with voice currents simultaneously with said modulation with currents of said base frequency, detecting means for said currents, means responsive to said voice currents, means responsive to said control currents and means responsive to currents of said base frequency for rendering said control current responsive means unresponsive to voice currents.
- a signal and control system the combination with a high frequency transmitter, means for modulating the output from said transmitter with voice currents and with control currents ⁇ having frequencies within the voice range, detecting means adapted to be supplied with currents from said transmitter, means responsive to said voice currents, means responsive to said control currents and additional means for rendering said control current responsive means unresponsive to said voice currents.
- a transmit-ter of high frequency current of means for modulating the output from said transmitter with voice currents
- additional means for modulating the output from said transmitter including an oscillation generator adapted to be connected to generate a base frequency and a plurality of control frequencies, means whereby said voice modulating means is rendered inoperative when said generator is connected to generate control frequencies and operative when said generator is connected to generate currents of said base frequency, demodulating means for said high frequency currents, means responsive to said voice currents, means responsive to said control frequenciesk and means responsive to said base frequency for rendering said control frequency responsive means unresponsive to said voice currents.
- a transmitter of high frequency currents of means for modulating said high frequency currents with voice currents, additional means for modulating said high frequency currents including anoscillation genera-tor normally connected to 'operate at a base frequency and adapted to be adjusted to operate at a plurality of control frequencies, switching means adapted in response to an adjustment of the frequency of said oscillation generator to render said voice modulating means inoperative and to connect said oscillationV generator to operate at one of said control frequencies, demodulating means for said high frequency currents and means associated therewith operable responsively to said modulating currents.
- the coin- Y bination with a transmitter of high frequency currents of means for modulating said high frequency kcurrentswith voice currents, additional means for modulating said high frequency currents including an oscillation generator adapted to be adjusted to Voperate at a bas-e frequency and a plurality of controlfrequencies, switching means adapted to connect said generator to operate at said base frequency and to establish an operative connection for said voice modulating means, said switching means being adapted in response to an adjustment of the frequency of said oscillation generator to interrupt said connections and to connect said generator to operate at the adjusted frequency, means including a time element for restoring said switching means to its initial position, de-y modulating means for the youtput of said transmitter and control means associated therewith operable responsively to said modulating currents.
- a trans- Vof a base frequency, meansfor detecting said modulatingcurrents, a plurality of tuned relays each ofsaid relays being adapted to respond to control currents of a certain frequency and-means responsive to currents of said base frequency for rendering said relays unresponsive to said voice currents.
- a high frequency transmitter means for modulating the output currents produced by said transmitter with voice currents, means operable selectively to modulate currents produced by saidtransmitter with control currents having one of a plurality of frequencies, and means responsive to operation of said last means to select a frequencyv for rendering the voicemodulating means inoperative for a predetermined interval and thereafter for automatically interrupting modulation of said output current by control current of said selected frequency.
- a high frequency transmitter means for modulating the output currents produced by said transmitter with voice currents, means operable selectively to modulate currentsiproduced by said transmitter with controlcurrents having'one of a plurality of frequencies, and means responsive to operation of said last means to select a frequency for: rendering the voice modulating means inoperative for a predetermined interval, for modulating said output currents during said interval with control current of selected frequencyv and for thereafter rendering saidvoice modulating means operative.
Description
Sept. l, 1931. F. KONN 1,821,758
SIGNAL AND` CONTROL sY-sTEM Filed June 29, 1927 `N b: -l o Q w @I N B Y w 5 OETffcTo/le 47 Mmmm@ AMP/ /F/Ee.
illlllf fvwm Inventor` FeILx Kohn Patented Sept. l", 1931 UNITED STATES PATENT OFFICE FELIX KONN, OF ERIE, PENNSYLVANIA. ASSIGNQB T Glitil'ERIAL` ELECTRIC COMPANY,
A C0311.ORATIQIT OF .NEW 'YORK lalzarmi. .um ooNrRoL svs'rEi/rv y Application inea :une .29,
My invention relates ,to signal and Vcontrol Y systems and more particularly to such systems as applied to communication and con trol between different train units of a single train, or between different trains, or between a stationary pointl and a moving vehicle.V Still more particularly my invention is primarily concerned with signal and control systems for operation between a leading, or master locomotive of a train and other `oco motives of the same train. n
In present day railway practice it is very frequent that freight trains are a mile or more in length, thereby necessitating the use of a number of locomotives. For practical reasons-it is desirable that the tractlve effort of these locomotives be distributed along the length of the train aszevenly as possible, i. e. that a plurality of small locomotives distributed along the length of the train be used in contra-distinction to the use of locomotives of large capacity located at the ends of the train 0r in a manner such that their effort is concentrated at a comparatively few points in the train. It is likewise desirable, in the interest of eiliciency and safety, where a plurality of locomotives, are used, that the functioning of all the different locomotives should be suitably coordinated, or that all of the various locomotives be 'controlled by a single operator.
One of the-purposes of my invention V.1s to provide means whereby the functioning of a number of locomotives may be controlled from a single master, or leading, locomotive of the train by means of high frequency cur` rents, such as are employed in the usual high frequency communication system. Am other purpose of my invention is to `provide means such that a single high frequency channel may be employed for comm-unication between different units, or different locomotives of a train and for control of either signal or power functions on the various units or locomotives, A further purpose is to provide means whereby these objects may be accomplished in a reliable and satisfactory manner and with a minimum of equipment.
I contemplate by my invention the use, between different units of a train, or between 1927, Serial No. 202,451.
different trains, of a high frequency communication system, such as that employed either in radio communication o-r in connection with communication by means of carrier currents transmitted over the lines of the usual power distribution system. In connection therewith I contemplate means whereby the high frequency currents of such a system may be modulated by means of currents, the frequencies of which are determined in accordance with the power or signaling function which is to be performed upon a remote loco` motive, or train unit, and means upon the different locomotives or train units operable responsively to the frequency of said modu` lating currents to perform the desired signal or power function.
The novel features which l believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, to-y gether with further objects and advantages thereof, will best be'understood by reference to the following description taken in connection with the accompanying drawing,which represents one embodiment of my invention.
With reference to the drawing, at A is illustrated the equipment which is provided upon the master locomotive of a train` and at B theequipment which is provided upon any of the subsidiar or ",pusher locomotives which may be distri uted uniformly through,- out the length of the train. This equipment may likewise be located upon any part of the train, orV on a separate train or at any point where signal or power functions are to be controlled. The .equipment located upon the master locomotive A includes a transmitterl of high frequency current suoli as is employed in the usual radio or carrier current communication system. This transmitter is adapted to supply high frequency currents through the transformer 2 and appropriate cou ling circuit 3 to a suitable conductor 4 lea ing to the other locomotives of the train. In the case of electric railways the conductor 4 may comprise the usual trolley wire located above the train, or in the case of steam railways it may comprise the rails, or special Wires provided for the purpose either upon the train or located upon poles along` the track. If desired the conductor d may be replaced by suitable antennae located upon each of the various train units whereby the contemplated communication and control may be effected by space radio. Associated with the transformer 2, which may be of the usual three Winding type, is an appropriate.
detector or demodulator 5, which is adapted to respond to received high frequency currents and to supply audio currentsto a receiver 6, or if desired, through audio amplifiers 7 to either a visible or audible signaling device S.
Likewise the equipment of the locomotive B includes a transformer 1 Wl ich is adapted to supply high frequency currents through the output transformer 2 and coupling circuit 3 to, the conductor l for communication 'from unit B to unit A. Associated with the transformer is a detector 5 which serves to demodulate the received high frequency Waves and supply audio currents to the telephone receiver 6 and through audio amplitiers 7 to the visible or audible signaling,` device 8. The devices 8 and 8 be used for calling purposes and 'may be adaptedto be disconnected from circuit when the operator lifts his receiver in response to a call.
As thus far described the system comprises substantially'the apparatus used in connection with the usual high frequency radio or carrier current communication system. ln connection With the apparatus on the locomotive A, I contemplate a source of alternating current having frequencies which are variable Within the voice range and means whereby the outputfrom the transmitter 1 may be modulated by means of these currents having definite frequencies determined in accordance with the operation which is to be performed upon a remote train unit. Lilie- Wise I contemplate means whereby the usual voice modulating means which comprises a part of the usual high frequency' communication system may be rendered inoperative during periods when control frequencies are being transmitted and is again rendered operative after these currents have been transmitted during `a time interval sufficient to permit the operation of the apparatus on' the remote train units to perform the desired function. As a source of such alternating currents an electron discharge device 9 is provided having the usual oscillation circuit comprisingthe condensers 10and 11 which are connected in series between the anode and the grid of the` discharge device 9 and in parallel with an inductance 12 through a conductor 13, inductance 12, conductor 1li, upper movable contact of the relayA 15 and conductor 16. Connected to this oscillatory circuit through the conductors 13 and 1G is the primary Winding of the output transformer 17, the secondary Winding of Which is connected to the modulatingl circuit 18 of the transmitter 1. .in parallel With the secondary Winding of the transformer 17 is a voicermodulating circuit including a source of direct current potential 19, a transmitter 20 and the lower movable contact of the relay 15.
With the relay l5 in the position shown in the drawing the oscillation generator 9 is connected to supply currents having a frequency determined by the inductance 12 to 'the modulating circuit of the transmitter l. These currents, fora purpose later to beset forth, are highin the audio range and are frequency Which l term the base frequency of the oscillation `generator. 21 represents an inductance which is divided into sections and which is adapted to be connected in series with the inductance 12 by a circuit incliuiiiu,r conductor 11i, inductancc 21, control arm 23, conductor 2li, conductor 25, contact 26, upper movable contact of the relay 15, conductor 16, condensers 1l and 10 and conductor The arrangement is such that When the relay 15 is in its upper position the inductance 12 determines the frequency ofthe oscillation `generator, whereas with the relay 15 in the lower position the inductance 12 plus those sections of the inductance 21v between the conductor 14 and the movable arm 03 vdetermine the frequency of the. oscillation generator. The relay 15 is adapted to be operated respousively to adjustment of the control handle 23 upon the inductance 21 by meansof an energizing circuit includingr the control handle conductor 24, source of potential 27, aetiuiting coil ofthe rela-y 15, conductor 28, and one of the contacts 29.
esseci; nd with the (uitput circuit of the unodulating deviav lis a telephone receiv- ",-aud through conductors and 3l, a
lli/Then 'ibis relay is deenerin its closed ation it connects a tuucd relays .Of-l. -l-l, 35, 3G, IS7, SS "h tho coingluctors il() and 31. i relays is' adapted to respond to c u. frefuuucv determined by the :7, 21 when the control handle 23 is as, for examuid, vwhen it is on the will respond, etc: X' 1 when rated to ne bridge nl source of 'on and details of 'lll'xe arm 4-1, l .ance 99 and ive lintents various positions by i pensive device lli mechanism. rn. be
which romani. which i" aus that of the usual locor f ated upon the locomotive l5, or that of any cuits may be caused to be energized directly n in response to therelays 33 to 38.
Likewise While I have described my invention with particular reference to its use between different locomotives or different units ular embodiment of the invention, it will of course be understood that I do not Wish to be limited thereto since many modifications both in the circuit arrangement and in the instrumetalities employed may be made Without departingfrom the spirit and scope of the `invention as set forth in the appended claims. What I claim as new and desire to secure by Letters Patent of the United States, is 1. In a signal and control system, the
combination with a source of high frequency oscillations ofmeans for modulating the output from said source With voice currents, means for selectively modulating the output from said source With control currents having y any one of a plurality of frequencies determined in accordance With the operation to be controlled, means for detecting said voice and control currents, a receiver for said voice currents and means responsive to the frequency of said control currents for controlling said operation. p
2. In a signal and control system, the combination With a high frequency transmitter, of means for modulating the output from said t 'ansmitter With voice currents, means for selectively modulating the output from said transmitter With control currents having any one of a plurality of frequencies determined in accordance with the operation to be controlled and for interruptig the operation of said voice modulating means, means for detecting said currents, means responsive to said voice currents and means responsive to the frequency of said control currents for controlling said operation.
3. In a signal and control system, the com- 'biation with a high frequency transmitter, of means for modulating the output from said transmitter With either voice currents or control currents, said voice current modulating means being inoperative during periods of control current modulation, and said control current having any one of a plurality of frequencies determined in accordance with the ulating the ouptut from said transmitter and means responsive to said control currents for controlling said operation.
'4. In a signal and control system, the combination with a transmitter of high frequency currents of means for modulating the output from said transmitter with voice currents, means for modulating the output from said transmitter With control currents having any one of a plurality of frequencies determined in accordance with the operation to be controlled, means for rendering said voice modulating means inoperative during periods of control current modulation, demodulating means for said high frequency currents and means responsive to the frequency of said control currents for controlling said operation.
5. In a signal and control system, the combination with a transmitter of high frequency currents, of means for modulating the output from said transmitter with voice currents, means for modulating the output from said transmitter with control currents the frequency of said cont-rol currents being Within the voice range and determined in accordance with the oseration to be controlled, means for rendering said voice modulating means inoperative during periods of control current modulation, demodulating means for said high frequency,currents, means respon sive `'to the frequency of said control currents for controlling saidoperations, and means whereby said control current responsive means is rendered unresponsive to voice currents.
6. In a signal and control system, the combination With a transmitter' of high frequency current, of means for modulating the output from said transmitter With voice currents, control currents and currents of base fre'- quency, demodulating` means for said high frequency currents, means responsive to said voice currents, means responsive to said con trol currents and means responsive to currents of said base frequency for rendering said control current responsive means unresponsive to said voice currents.
7. In a signal and controlsystem the combination with a high frequency transmitter, of means for alternately modulating the output from said transmitter with control currents having frequencies within the voice range and Wi yh currents of a base frequency` means for modulating the output from said transmitter with voice currents simultaneously with said modulation with currents of said base frequency, detecting means for said currents, means responsive to said voice currents, means responsive to said control currents and means responsive to currents of said base frequency for rendering said control current responsive means unresponsive to voice currents.
loperation to be controlled, means for demod- S. In a signal and control system, the combination with a high frequency transmitter, means for modulating the output from said transmitter with voice currents and with control currents `having frequencies within the voice range, detecting means adapted to be supplied with currents from said transmitter, means responsive to said voice currents, means responsive to said control currents and additional means for rendering said control current responsive means unresponsive to said voice currents.
9. In a signal and control system, the combination with a transmit-ter of high frequency current, of means for modulating the output from said transmitter with voice currents, additional means for modulating the output from said transmitter including an oscillation generator adapted to be connected to generate a base frequency and a plurality of control frequencies, means whereby said voice modulating means is rendered inoperative when said generator is connected to generate control frequencies and operative when said generator is connected to generate currents of said base frequency, demodulating means for said high frequency currents, means responsive to said voice currents, means responsive to said control frequenciesk and means responsive to said base frequency for rendering said control frequency responsive means unresponsive to said voice currents.
v10. In a signal and control system, the combination with a transmitter of high frequency currents, of means for modulating said high frequency currents with voice currents, additional means for modulating said high frequency currents including anoscillation genera-tor normally connected to 'operate at a base frequency and adapted to be adjusted to operate at a plurality of control frequencies, switching means adapted in response to an adjustment of the frequency of said oscillation generator to render said voice modulating means inoperative and to connect said oscillationV generator to operate at one of said control frequencies, demodulating means for said high frequency currents and means associated therewith operable responsively to said modulating currents.
11. In a signal and control system, the coin- Y bination with a transmitter of high frequency currents, of means for modulating said high frequency kcurrentswith voice currents, additional means for modulating said high frequency currents including an oscillation generator adapted to be adjusted to Voperate at a bas-e frequency and a plurality of controlfrequencies, switching means adapted to connect said generator to operate at said base frequency and to establish an operative connection for said voice modulating means, said switching means being adapted in response to an adjustment of the frequency of said oscillation generator to interrupt said connections and to connect said generator to operate at the adjusted frequency, means including a time element for restoring said switching means to its initial position, de-y modulating means for the youtput of said transmitter and control means associated therewith operable responsively to said modulating currents.
12. In a signal and control system, a trans- Vof a base frequency, meansfor detecting said modulatingcurrents, a plurality of tuned relays each ofsaid relays being adapted to respond to control currents of a certain frequency and-means responsive to currents of said base frequency for rendering said relays unresponsive to said voice currents.
14. In combination, a high frequency transmitter, means for modulating the output currents produced by said transmitter with voice currents, means operable selectively to modulate currents produced by saidtransmitter with control currents having one of a plurality of frequencies, and means responsive to operation of said last means to select a frequencyv for rendering the voicemodulating means inoperative for a predetermined interval and thereafter for automatically interrupting modulation of said output current by control current of said selected frequency.
15. In combination, a high frequency transmitter, means for modulating the output currents produced by said transmitter with voice currents, means operable selectively to modulate currentsiproduced by said transmitter with controlcurrents having'one of a plurality of frequencies, and means responsive to operation of said last means to select a frequency for: rendering the voice modulating means inoperative for a predetermined interval, for modulating said output currents during said interval with control current of selected frequencyv and for thereafter rendering saidvoice modulating means operative. g
In witness whereof, I have hereunto set my hand this 27th day of June, 1927.
' FELIX KONN.
iso y
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US202451A US1821758A (en) | 1927-06-29 | 1927-06-29 | Signal and control system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US202451A US1821758A (en) | 1927-06-29 | 1927-06-29 | Signal and control system |
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| Publication Number | Publication Date |
|---|---|
| US1821758A true US1821758A (en) | 1931-09-01 |
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|---|---|---|---|
| US202451A Expired - Lifetime US1821758A (en) | 1927-06-29 | 1927-06-29 | Signal and control system |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2427979A (en) * | 1943-09-04 | 1947-09-23 | Union Switch & Signal Co | Communication and control system for airplanes |
| US2484680A (en) * | 1945-01-30 | 1949-10-11 | Union Switch & Signal Co | Railway train communication and alarm system using modulated carrier currents |
| US2566106A (en) * | 1947-12-09 | 1951-08-28 | Farmers Engineering & Mfg Co | Emergency communication system, particularly for mines |
| US2604544A (en) * | 1949-12-30 | 1952-07-22 | W C Dillon & Company Inc | Carrier telephone system with audio-frequency signaling |
| FR2460571A1 (en) * | 1979-06-29 | 1981-01-23 | Chancrogne Bernard | Emergency telephone system for lift - has HF transmitter receiver coupled to central surveillance post using twin cable lift alarm circuit |
-
1927
- 1927-06-29 US US202451A patent/US1821758A/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2427979A (en) * | 1943-09-04 | 1947-09-23 | Union Switch & Signal Co | Communication and control system for airplanes |
| US2484680A (en) * | 1945-01-30 | 1949-10-11 | Union Switch & Signal Co | Railway train communication and alarm system using modulated carrier currents |
| US2566106A (en) * | 1947-12-09 | 1951-08-28 | Farmers Engineering & Mfg Co | Emergency communication system, particularly for mines |
| US2604544A (en) * | 1949-12-30 | 1952-07-22 | W C Dillon & Company Inc | Carrier telephone system with audio-frequency signaling |
| FR2460571A1 (en) * | 1979-06-29 | 1981-01-23 | Chancrogne Bernard | Emergency telephone system for lift - has HF transmitter receiver coupled to central surveillance post using twin cable lift alarm circuit |
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