US3408646A - System for localizing trains along a track - Google Patents

System for localizing trains along a track Download PDF

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US3408646A
US3408646A US63718767A US3408646A US 3408646 A US3408646 A US 3408646A US 63718767 A US63718767 A US 63718767A US 3408646 A US3408646 A US 3408646A
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track
system
train
along
frequency
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Simon Jean-Claude
Broussaud Georges Jean
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CSF Compagnie Generale de Telegraphie Sans Fil Cie
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/27Adaptation for use in or on movable bodies
    • H01Q1/32Adaptation for use in or on road or rail vehicles
    • H01Q1/3208Adaptation for use in or on road or rail vehicles characterised by the application wherein the antenna is used
    • H01Q1/3225Cooperation with the rails or the road
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B61RAILWAYS
    • B61LGUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
    • B61L25/00Recording or indicating positions or identities of vehicles or vehicle trains or setting of track apparatus
    • B61L25/02Indicating or recording positions or identities of vehicles or vehicle trains
    • B61L25/021Measuring and recording of train speed
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B61RAILWAYS
    • B61LGUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
    • B61L25/00Recording or indicating positions or identities of vehicles or vehicle trains or setting of track apparatus
    • B61L25/02Indicating or recording positions or identities of vehicles or vehicle trains
    • B61L25/026Relative localisation, e.g. using odometer
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B61RAILWAYS
    • B61LGUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
    • B61L3/00Devices along the route for controlling devices on the vehicle or vehicle train, e.g. to release brake, to operate a warning signal
    • B61L3/02Devices along the route for controlling devices on the vehicle or vehicle train, e.g. to release brake, to operate a warning signal at selected places along the route, e.g. intermittent control simultaneous mechanical and electrical control
    • B61L3/08Devices along the route for controlling devices on the vehicle or vehicle train, e.g. to release brake, to operate a warning signal at selected places along the route, e.g. intermittent control simultaneous mechanical and electrical control controlling electrically
    • B61L3/12Devices along the route for controlling devices on the vehicle or vehicle train, e.g. to release brake, to operate a warning signal at selected places along the route, e.g. intermittent control simultaneous mechanical and electrical control controlling electrically using magnetic or electrostatic induction; using radio waves
    • B61L3/125Devices along the route for controlling devices on the vehicle or vehicle train, e.g. to release brake, to operate a warning signal at selected places along the route, e.g. intermittent control simultaneous mechanical and electrical control controlling electrically using magnetic or electrostatic induction; using radio waves using short-range radio transmission
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01PWAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P3/00Waveguides; Transmission lines of the waveguide type
    • H01P3/16Dielectric waveguides, i.e. without a longitudinal conductor

Description

1963 JEAN-CLAUDE SIMON ETAL 3,403,646

SYSTEM FOR LOCALIZING TRAINS ALONG A TRACK 4 Sheets-Sheet 1 Filed May 9, 1967 1 u awn u 55 it w. A h

1968 JEAN-CLAUDE SIMON ETAL 3,408,645

SYSTEM FOR LOCALIZING TRAINS ALONG A TRACK 4 Sheets-Sheet 5 Filed May 9, 1967 JEANCLAUDE SIMON ETAL 3,408,646

SYSTEM FOR LOCALIZING TRAINS ALONG A TRACK Oct. 29, 1968 Filed May 9, 1967 4 Sheets-Sheet 4 Fig.6

Fig.9

RECEIVER DIRECTIONAL COUPLER 4 TRANSMITTER Fig.10

United States 3,408,646 SYSTEM FOR LOCALIZIN G TRAINS ALONG A TRACK Jean-Claude Simon and Georges Jean Broussaud, Paris, France, assignors to CSF-Compagnie Generale de Telegraphie Sans Fil, a corporation of France Filed May 9, 1967, Ser. No. 637,187 Claims priority, applicltionoFrance, May 16, 1966,

,so 10 Claims. (31. 343-65) ABSTRACT OF THE DISCLOSURE The present invention relates to safety systems for controlling the train traflic along a track.

The conventional solution of this problem consists in defining track sections and providing signalling devices for preventing collisions, for example by preventing that two trains may -be simultaneously in the same section. This solution is no longer appropriate, in view of the rising traflic density, which necessitates an increase in the speed, the frequency and the length of trains which are permitted to run along the same track. It is also subject to atmospherics which can affect the interpretation of signals optically transmitted to the driver.

A modern solution of problems of detection and telemetering is provided by radar systems. However, most of radar systems are based on the angular detection of targets by means of a highly directional antenna radiating into space. This is obviously superfluous for locating trains running along a track and it is suitable to use the track itself for guiding the radioelectric control signals. Unfortunately, railway rails have a geometry which lends itself badly for guiding electromagnetic waves. This results in the use of complex transmission lines for guiding the waves parallel to the track.

According to the present invention there is provided a system for locating trains of cars along a track comprising a dielectric wave guide, extending along said track, for receiving ultra-high frequency wave energy from said cars and propagating said energy as a surface wave and reflector means spaced along said track for reflecting said energy towards said cars.

For'a better understanding of the invention and to show how the same may be carried into effect, reference will be made to the drawings accompanying the following description and in which:

FIG. 1 is a view in perspective of a carriage moving along a track;

FIG. 2 is a plan view showing the principle of the system according to the invention;

FIG. 3 is an elevation view of the track equipped with responders;

FIG. 4 is a block diagram of the radioelectric locating system;

FIG. 5 is an explanatory drawing;

FIG. '6 shows in elevation a first device for exciting ultra-high frequency Waves;

FIG. 7 is an end view of a second device for exciting ultra-high frequency waves;

atent FIG. 8 is a transverse section of one embodiment of a responder;

FIG. 9 is an end view of a third embodiment of a device for exciting ultra-high frequency waves; and

FIG. 10 is a plan view of the arrangement of FIG. 9.

FIG. 1 shows a track 1 of a special type along which moves a carriage 2, only the outline of which has been drawn. By way of non-limitative example, the track 1 has the form of a horizontal T shaped concrete beam having a base EFGH. The carriage 2 floats on this track, being supported there upon on a cushion of air. However, without departing from the principle of the invention, the construction may be modified to comprise rails and wheels adapted to roll the carriage 2 along the track 1.

According to the invention, a part of the track 1 behaves after the manner of a dielectric waveguide with the axis 0z, having in the plane xoy a predetermined transverse cross-section ABCD. In FIG. 1, this crosssection is formed by the vertical arm of the concrete beam 1. On board of the carriage 2, excitation means 3 are provided, which are coupled to the track 1, serving as a waveguide, in order to excite therein a surface wave, progressing parallel to o z. FIG. 2 shows the front of a train 21 and the rear of a train 22, which precedes the former one. The train 21 is equipped with an ultra-high frequency system 4, adapted to transmit and to receive locating signals via antennae 3, connected to the vertical arm of the runway ,1. Inside the environment with the refraction index 1 and the permittivity e forming the dielectric guide, the transmitted waves suffer a total reflection, when their incidence 0 is greater than the critical angle 0,, given by sin 0 m where 1 is the index of the environment surrounding the guide.

Under these conditions, a surface wave can be formed about the dielectric guide and may progress along o z with a phase velocity v given by the formula:

cos 0 where is the phase velocity of electromagnetic waves in the environment with the index 1 It can be shown that the surface wave excited around the guide with the width a is damped exponentially with increasing distance from the lateral surfaces of the guide. It can also be shown that the efiicient section, where the electromagnetic field has an attenuation less than He, has a radius p with int. 1 oxt. P 2

It is therefore possible to use the dielectric guide for propagating with low attenuation a surface wave which remains confined within the immediate vicinity of the track 1. If the surface wave encounters during its progression along the track a conducting obstacle, such as the rear of the train 22, the electromagnetic energy is reflected in the same wave mode towards the train 21 which receives a delayed echo in response to the incident wave train. The guiding of the wave is still effective if the guide is slightly curved. Amongst the modes capable of being propagated in the form of surface waves about a dielectric waveguide, may be mentioned the mode TM shown in FIGS. 1 and 2; it is also possible to excite a TE mode or a hybrid TEM mode.

According to a first embodiment of the radioelectric system according to the invention, one branch of the track 1 is used as dielectric guide. The permittivity of the concrete used being three times as high as that of air, and the losses remaining small at the intended frequencies, it can be shown that, with a carrier frequency of 300 to 500 mc./s., a beam one metre high and 40 cm. thick can transmit a surface wave having a linear attenuation of a.

few decibels per kilometre.

Taking into account possible homogeneity defects, ranges of several kilometres are possible with a transmitting power of a mean value of a few watts.

FIG. 3 shows, in elevation, a track 1 and two trains 21 and 22 moving one behind the other from the left to the right. At regular intervals P (for example, of one kilo metre), responder beacons 5 have been incorporated into the track, which, on interrogation by the locating system mounted on board the train 21, transmit according to a predetermined code a surface wave directed towards this system.

According to the invention, the beacons p, p+1, p+2, p+i p-l-k, are interrogated one after the other by the radioelectric system mounted on board the train 21, and if no train 22 is between it and the train 21, the beacons 5 supply k-l-l coded information items, which enable the radioelectric system of locating instantaneously the exact position of the train 21. In the case that the train 22 masks the (p+i)th beacon 5, the surface wave coming from the train 21 is reflected by the train 22 without interrogating the following beacons; the telemetering system of the train 21 receives 1 coherent information items instead of k+1 and it may be concluded that there is an obstacle or that there is a failure in the operation of the beacons, which necessitates anyway the stopping of the train 21.

In FIG. 4, an embodiment is shown of a block diagram of the radioelectric system according to the invention. The dielectric guide 1 is connected to an antenna 3, comprising for example an array of radiating elements and phase shifting means, for excitating a surface wave propagating towards the right and for picking up the wave propagating in the opposite direction. With the dipoles shown in FIG. 4, a surface wave TM can be excited the electrical and magnetic vectors of which are shown in FIG. 1. The antenna 3 is coupled through a directional coupler 6 to an ultra-high frequency transmitter 7 and to an ultra-high frequency receiver 8; the transmitter 7 is modulated by a modulator 10 which causes a frequency modulation in the shape of symmetrical saw-teeth. The output of the receiver 8 feeds bandpass filters 11, 12, 13, 14 and 15 which separate, in accordance with their respective frequencies, the different locating signals collected by the antenna 3. The locating signals transmitted by the filters 11, 12 and 13 are compared in a telemetering system 16 according to the law of modulation provided by the modulator 10, in order to determine their respective propagation times. These times are then compared between themselves by means of a correlator 17 which supplies the indication of the position z,, of the vehicle carrying the radioelectric system. A differentiator 18, connected to the output of the correlator 17 gives the absolute velocity v of the train. The filter 14 transmits directly to a detector 19 a fixed echo 7 produced by means of a resonant cavity 9, a socalled echo-box, permanently connected to the output of the transmitter 7. This makes it possible to control permanently the operation of the transmit-receive assembly. The filtre 15 transmits an echo caused by the reflection from an obstacle 22, located at any distance z in front of the transmitting vehicle 21; this echo is mixed with a signal transmitted by the antenna 3 in a mixer 23, which supplies a signal whose frequency is proportional to this distance. A frequency discriminator 24 converts this measuring signal into the distance Z which is applied to a differentiator 25 to supply the relative speed v of the transmitting vehicle 21 relative to the obstacle 22. The information z 2,, v v and 'y are finally applied to a circuit 26 which ensures the control of the propulsion unit of the train 21.

FIG. 5 shows at (a) the variation as a function of the time of the frequency of the signal transmitted by the radioelectric system of FIG. 4. The transmission wave is continuous and propagates as a surface Wave along the dielectric guide 1. During its propagation in front of the vehicle 21, the wave encounters the beacons 5 which are frequency coded so as to reflect a signal only if its frequency has a certain value. The beacon p responds to the frequency of interrogation f the beacon p+1 responds to the frequency fp-I-l and so on, and the echoes received are Ep, Ep+1, Ep+2 etc., in accordance with the diagrams (b), (c) and (d) in FIG. 5. It may be seen, upon comparing these diagrams with the diagram (a), that the propagation times r, r-l-R, r+2R are directly related to the distances p, p+-P, and p+2P which separate the beacons 5 from the train 21 in FIG. 3. Hence, from these times, the absolute position of the train 21 along the track 1 can be calculated. If the propagation time r+2R is abnormally small, it may be assumed that an obstacle 22 masks the beacon p+2 which should have determined its duration. This abnormality reveals primarily the presence of an obstacle between two consecutive beacons. This obstacle is also detected by an intensive echo which it returns towards the receiver of the radioelectric system. This echo, delayed as a function of the propagation distance, has a frequency modulation delayed relative to that of the transmitted wave. Diagram (e) shows in solid lines the modulation of the received echo and in broken lines that of the transmitted wave and it may be readily seen that the gap A is proportional to the distance 2,- separating the train 21 from the obstacle 22. By measuring the frequency gap A a second means is provided for locating the obstacle along the track 1. These two methods of location insure a great operational reliability of the system and provide valuable information for controlling the run of the vehicles. The echo-box 9 affords additional safety since it creates a systematic echo 7, such as is shown in the diagram (f) in FIG. 5 which makes it possible to control permanently the operation of the transmit-receive assembly.

Without thereby departing from the principle of the invention, the block diagram shown in FIG. 4 may be modified in many ways. More particularly, the radioelectric system may be pulse modulated. This makes it possible to use in the receiver a compression method which improves the precision in the locating of targets. In this case, the beacons may be coded, for retransmitting a pulse train forming a digital position code. Whatever the method adopted, it is possible, without using pulse compression, to determine distances within :15 metres with a radioelectric system transmitting within a frequency band of 50 mc./s. This band may be reduced by providing the suitable information processing and this reduction is limited only by the signal-to-noise ratio which is anyway favourable in view of the small ranges required.

If the modulation shown diagrammatically in FIG. 5 is used, it can be readily shown that the choice of symmetrical saw-teeth makes it possible to compensate frequency shifts caused by the Doppler-Fizeau effect. It is also possible to utilise systematically this measurable effect as a means for determining the speeds at which the train is approaching the beacons and fixed or mobile obstacles.

FIG. 6 shows in elevation a track 1 and an antenna of the YAGI type, capable of exciting about the vertical arm of the track 1 a surface wave according to the TE mode. The aperture of the antenna 31 must cover the eiiicient section of the surface wave which leads to arrange the antenna on either side of the vertical arm of the track 1.

FIG. 7 shows an end view of an antenna with distributed excitation. It comprises an electrode 32 sliding over the top of the track 1 and a pair of electrodes 33, connected electrically. The electrodes 32 and 33 form an excitation line with the axis parallel to the track 1. This line is coupled to a radiating line formed by two dielectric plates 34 which excite the surface wave according to one of the modes TE, TM or TEM.

FIG. 8 shows diagrammatically a responder beacon 5 embedded in the track 1. It consists of a radiating element 51 placed into a cavity formed in the wall of the track 1. This element is weakly coupled with the surface wave whose efiicient cross-section surrounds the vertical arm, acting as a dielectric guide. The element 51 is electrically coupled through a directional coupler 52 with a receiver 53 and a transmitter 54 which are both tuned to a predetermined frequency f,,, depending on the rank of the beacon. When the beacon is interrogated by a signal with the frequency f the receiver 53 controls the retransmission of the same frequency f by the transmitter 54.

FIG. 9 shows an end view of a track 1 surmounted by a dielectric guide 100. This arrangement is used where the vertical arm of the beam 1 is unsuitable for guiding the surface wave. This is the case where centimetre waves are used in preference to metre waves. For exciting the surface wave around the guide 100, an antenna according to FIG. 10 is used. It comprises an exciter waveguide 104, one end of which is equipped with a dielectric block 103, cut to a wedge in order to obtain a gradual coupling with the efficient section of the wave to be excited around the guide 100. The guide 100 can be formed from a dielectric with low losses at the frequencies used. It may also be formed of a periodic array of conducting obstacles forming an artificial dielectric.

Of course the invention is not limited to the embodiments described and shown which were given solely by way of example.

What is claimed is:-

1. A system for locating trains of cars along a track comprising a dielectric wave guide extending along said track for receiving ultrahigh frequency wave energy from said cars and propagating said energy as a surface wave and a plurality of passive responder-beacons spaced long said track and programmed for reflecting received energy towards said cars in accordance with a predetermined code.

2. A system as claimed in claim 1, wherein said wave guide is a concrete beam.

3. A system as claimed in claim 1, wherein, said train being shaped for floating along the vertical branch of a T shaped beam, resting upon its horizontal branch, said wave guide is said vertical branch.

4. A system as claimed in claim 1, wherein said guide is an artificial dielectric guide.

5. A system as claimed in claim 1, wherein said responder-beacons are programmed for responding to respective predetermined frequencies only.

6. A transmit-receive system for transmitting from cars ultrahigh frequency energy and for receiving echoes from responder-beacons and obstables in a system as claimed in claim 1 comprising transmitter means for exciting a surface wave along said wave guide in the direction of motion of said cars, receiving means for picking up said surface wave as reflected by said responder-becaons and obstacles ahead of said cars, first metering means, coupled to said receiving means, for measuring the distance from said obstacles to said cars and second metering means, coupled to said receiving means, for determining, from said echoes from said responder-beacons, the position of said cars along said track.

7. A system as claimed in claim 6, further comprising means for differentiating said position and said distance with respect to time for respectively determining the absolute speed of said cars and the relative speed of said cars with respect to said obstacles.

8. A system as claimed in claim 6, wherein said excitation means comprises an end-fire antenna.

9. A system as claimed in claim 8, wherein said antenna comprises two elements respectively coupled to the two sides of said wave guide.

10. A system as claimed in claim 6, wherein said transmitter means comprise means for frequency modulating said surface wave and said second metering means comprises a plurality of channels respectively tuned to different frequencies respectively corresponding to different responder-beacons.

References Cited UNITED STATES PATENTS 3,305,682 2/1967 Bolster et al. 246167 2,716,186 8/1955 Ford 246-l87 2,702,342 2/1955 Korman 246187 2,698,377 12/1954 Korman 7A6-187 FOREIGN PATENTS 1,378,440 10/ 1964 France.

939,248 11/1948 France.

RODNEY D. BENNETT, Primary Examiner.

C. L. WHITHAM, Assistant Examiner.

US63718767 1966-05-16 1967-05-09 System for localizing trains along a track Expired - Lifetime US3408646A (en)

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Application Number Priority Date Filing Date Title
FR61800A FR1494132A (en) 1966-05-16 1966-05-16 vehicles trains locating radio system operating on a guiding track

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DE (1) DE1591043A1 (en)
FR (1) FR1494132A (en)
GB (1) GB1180261A (en)
NL (1) NL6706787A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4063237A (en) * 1974-02-21 1977-12-13 Robert Bosch Gmbh Distance measuring system, particularly for spacing of moving vehicles
US4254418A (en) * 1978-08-23 1981-03-03 Sperry Corporation Collision avoidance system using short pulse signal reflectometry
US4331959A (en) * 1979-05-05 1982-05-25 Messerschmitt-Boelkow-Blohm Gesellschaft Mit Beschraenkter Haftung Method and apparatus for detecting a defective object on a lane or track
US4951574A (en) * 1988-05-26 1990-08-28 Daifuku Co., Ltd. Conveyor system using automotive cart
WO2011076512A1 (en) * 2009-12-21 2011-06-30 Siemens Aktiengesellschaft Method and device for monitoring the totality of a railborne train

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE755974R (en) * 1968-10-23 1971-02-15 Kabel Metallwerke Ghh high line
FR2180582B1 (en) * 1972-04-21 1976-01-16 Thomson Csf Fr
FR2648053B2 (en) * 1989-01-31 1993-01-08 Jouef Ind A control device has a distance to an electric toy installation on circuit
FR2642324B1 (en) * 1989-01-31 1992-10-30 Jouef Ind A control device has a distance to an electric toy installation on circuit
GB9025504D0 (en) * 1990-11-23 1991-01-09 Mcalpine Kenneth R Speed detector
ITTO20030978A1 (en) * 2003-12-05 2005-06-06 Ansaldo Segnalamento Ferroviario S P A Boa (balise) for railway signaling and method of construction of the buoy itself.

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR939248A (en) * 1944-06-27 1948-11-08 Westinghouse Freins & Signaux Improvements to the devices by induction for repeaters cab signaling system type track circuit for railway and similar
US2698377A (en) * 1949-02-09 1954-12-28 Rca Corp Railway signaling system for measuring distance between trains
US2702342A (en) * 1948-11-20 1955-02-15 Rca Corp Traffic control by radar
US2716186A (en) * 1949-12-28 1955-08-23 Rca Corp Signalling system
FR1378440A (en) * 1963-12-13 1964-11-13 Sumitomo Electric Industries wave transmission lines on the surface
US3305682A (en) * 1963-07-26 1967-02-21 Gen Electric Ranging system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR939248A (en) * 1944-06-27 1948-11-08 Westinghouse Freins & Signaux Improvements to the devices by induction for repeaters cab signaling system type track circuit for railway and similar
US2702342A (en) * 1948-11-20 1955-02-15 Rca Corp Traffic control by radar
US2698377A (en) * 1949-02-09 1954-12-28 Rca Corp Railway signaling system for measuring distance between trains
US2716186A (en) * 1949-12-28 1955-08-23 Rca Corp Signalling system
US3305682A (en) * 1963-07-26 1967-02-21 Gen Electric Ranging system
FR1378440A (en) * 1963-12-13 1964-11-13 Sumitomo Electric Industries wave transmission lines on the surface

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4063237A (en) * 1974-02-21 1977-12-13 Robert Bosch Gmbh Distance measuring system, particularly for spacing of moving vehicles
US4254418A (en) * 1978-08-23 1981-03-03 Sperry Corporation Collision avoidance system using short pulse signal reflectometry
US4331959A (en) * 1979-05-05 1982-05-25 Messerschmitt-Boelkow-Blohm Gesellschaft Mit Beschraenkter Haftung Method and apparatus for detecting a defective object on a lane or track
US4951574A (en) * 1988-05-26 1990-08-28 Daifuku Co., Ltd. Conveyor system using automotive cart
WO2011076512A1 (en) * 2009-12-21 2011-06-30 Siemens Aktiengesellschaft Method and device for monitoring the totality of a railborne train

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FR1494132A (en) 1967-09-08
GB1180261A (en) 1970-02-04
BE698502A (en) 1967-11-16
DE1591043A1 (en) 1970-04-09
NL6706787A (en) 1967-11-17

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