AU683650B2

AU683650B2 - Trainline system using an electromagnetic communication link

Info

Publication number: AU683650B2
Application number: AU64538/94A
Authority: AU
Inventors: Andre Martin
Original assignee: Primetech Electronics Inc
Current assignee: Primetech Electronics Inc
Priority date: 1994-06-03
Filing date: 1994-06-03
Publication date: 1997-11-20
Anticipated expiration: 2014-06-03
Also published as: AU6453894A; IN188632B

Description

1

AUSTRALIA

Patents Act 1990 Primetech Electroniques Inc.

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "Trainline system using an electromagnetic communication link" e o o The following statement is a full description of this invention including the best method of performing it known to us:-

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IP TECHNICAL FIELD The invention relates to a novel cornnunication link for permitting communications between cars of a multi-car vehicle such as railway or subway trains. More specifically, the invention relates to such a comimunication link which includes free space radio communications between adjacent cars of the railroad or subway train.

BACK(GROUND ARTI In ord~r to adapt to changing system requirements, such as passenger or freight volume, routing, maintenance, crew or rolling stock ~availability, etc., rail cars are coupled and :uncoupled frequently. Train configuration and reconfiguration in this sense represents a **20 significant proportion of all train operation, whether considered in terms of rolling -stock-hours, man-hours, out-of-service hours, or whatever.

Therefore, these processes must be made as simple and as automated as possible.

While it is true that trains are made up a .:..variety of different types of cars, and in some cases, certain groups of cars are rarely uncoupled, it is nonetheless a f act that a great number of individual couplings and uncouplings are performed every day. An example of a present system is illustrated in U.S. Patent 5,121,410, Demarais, June 9, 1992. As can be seen in Figure 4 and 5 of the '410 patent, communication lines between cars (car -2 n-1, car n and car n+l) is effected by twisted pairs of wires.

This invention addresses the problem of how to provide adequate information transfer between cars without inhibiting train car coupling or uncoupling.

This invention proposes a solution which provides high-volume, high-reliability information transfer between cars.

information transfer between devices installed on different cars, in the form of electrical signals, has been a common feature of.

trains for a number of years. The electrical pathway that carries these signals is called a 15 "trainline". It is made up of a bundle of wires, each of which is connected in an electrically continuous path over the length of the train.

On board devices that use the trainline can interact with each other in a wide variety of ways. For example, a device on one car, such as a switch, may be used to control a number of similar devices, such as lights, on every car of the train.

For another example, a specific type of sensor may be installed on every car. if certain conditions arise on one car, the sensor may need to activate a warning buvzzer installed in the cab of the head car.

Many other configurations are possible.

The changing trainline information transfer requirements brought on by advances in electronic technology over the past two decades have given rise to rnew problems for trainline designers.

Two interrelated factors are at issue here: information volume and information reliability.

I

-3 in general, the volume of information transferred between rail cars has increased over the period mentioned. It promises to continue to increase f or some time to come, as train systems on board each car utilize more and more electronic and electrical equipment. This increased information f low may be addrzessed in two ways. The increased flow m~ay be. handled by an increasing number of wires, or else each wire must handle a larger volume of information.

Reliability of information transfer betweien cars is and always has been essential to safe, efficient train operation. Within each car, reliability is accomplished by providing mechanically secure conventional electrical .*.connectors that are rarely opened. However, for communications between adjoining cars, the connecting elements on the adjoining cars must be automatically and frequently connected and disconnected, rendering conventional electrical connectors inefficient.- The use of such connecting elements cause many problems leading to a large percentage of subway service interruptions. Some of the problems are as follows: 1. Faulty electrical contact caused by pin cc,...oxidation.- 2. Faulty electrical contact caused by dirt, e~e.Cgrease and foreign matter on pins that accumulates when the pins are disconnected and therefozre exposed.

Electrical Contact is prevented when a pin f ails to spring back out to its proper 4position due to accumulated dirt, grease and foreign matter inside the pin tube.

4. Electrical contact is prevented when returned springs fail due to loss of spring elasticity, which in turn is caused by de-tempering of the spring steel when abnormally high electrical current passes through the spring rather than the electrical shunt.

All of the above problems produce service interruptions and require expensive maintenance.

Periodically, the pins must be. Ohecked and cleaned to'ensure correct operation.

It is also known in the art to use optical, arrangements to provide communication links betw&en cars within a subset, and between the subsets of a train, as illustrated in U.S. Patent 4,682,144, Ochiai et al, July 21, 1987, Such a system. is illustrated in Figure 4 of the '144 patent.

The problem with optical systems in the environment of either subway or railroad trains is that. the systems are operating in very dirty environments so that the optical couplers will very shortly become dirty themselves. Due to the dirt which will accumulate on the optical couplers, optical transmission is degraded and possibly :..completely eliminated. Accordingly, the system as *illustrated in the '144 patent is not a practical solution to the provision to communication links between the end cars of subsets of a train.

In U.S. Patent 3,994,459, Miller et al, November 30, 1976, a radio system is used to provide communications between a car which is derailed from a train and the remainder of the train. -However, 5 the '459 patent does not teach any other communications between the cars of the train using radio signals.

Another factor affecting reliability is the increase in information volume mentioned above.

All else being equaal, as inforni~tion volume increases, overall reliability tends to decrease.

In summary, current train communications systems attemipt to provide reliability by two methods: couple.r pins and cable connectors. While the method of cable connectors between cars provides excellent reliability, it makes coupling and uncoupling the cars a laborious process. On the other hand, although coupler pins provide excellent ease of operation, they require high maintenance to maintain adequate reliability. coupler pins are :*sensitive to environmental factors, and other problems. Bly far the highest incidence of communication failure, especially intermittent failure, occurs due to coupler pin problems.

Increasing the n umber of wires may work up to a point, but limitations are imposed on this method by a number of factors. Among the most serious of these factors is the problem of large numbers of electrical connections between cars that must be coupled and uncoupled frequently. These connections are at best a trade-off between reliability and automation; as their numbers increase, reliability and/or automation are reduced.

Increasing the volume of information handled by each wire eliminates the necessity of large numbers of electrical connections between cars. However, the high volume of information carried by each wire makes these connections vulnerable to both data loss and increased maintenance, due reliability problems associated with the current state of the art of high-volume information flow through coupler pins.

U.S. Patent 3,696,758 discloses a communication link which uses inductive signals. With such signals there is less need for electromagnetic shielding so little is provided. The arrangement described in U.S. 3,696,758 could not be used with radio frequency signals without causing and incurring substantial electromagnetic interference.

DISCLOSURE OF THE INVENTION It is therefore an object of the invention to provide a communication link for communications between cars of a train which overcomes the disadvantages of the prior art.

It is a more specific object of the invention to "provide such a novel communications link which comprises a radio link through free space.

It is a still more specific object of the invention to provide such a novel communications link which comprises a multiplexer and a demultiplexer on selected ones of the cars of the train.

In accordance with the present invention there is 25 provided a communication link for permitting communications between adjacent cars of a multi-car :vehicle, said link comprising: on at least a first one of said cars, a first multiplexing/demultiplexing means for multiplexing first digital signals representative of the status or control signals of various systems on said first one of said cars, and for processing said first digital signals into a first digital trainline signal; (ii) first means for converting said first digital -~CC4 trainline signal to a first electromagnetic wave signal; and (iii) a first antenna mounted on one end of said first one of said cars for transmitting said first electromagnetic wave signal; in use said first multiplexing/demultiplexing means converting a second electromagnetic wave signal into a second digital trainline signal to provide second digital signals representative of the status or control signals of various systems on a second one of said cars and said first antenna receiving said second electromagnetic wave signal; on said second one of said cars, a second multiplexer/demultiplexer means for multiplexing said second digital signals, and for processing said second digital signals into a second digital trainline signal; (ii) second means for converting said second digital trainline signal to a second electromagnetic wave 20 signal; and (iii) a second antenna mounted on said second one of said cars at an end thereof adjacent to the end of the first car on which said first antenna is mounted; in use said second antenna transmitting said second 25 electromagnetic wave signal; said second multiplexing/demultiplexing means converting said first electromagnetic wave signal into a first digital Strainline signal to provide first digital signals representative of the status or control signals of various systems on said first one of said cars; and said second antenna receiving said first electromagnetic wave signals; whereby communications can be sent from said first one of said cars to said second one of said cars and from 8 said second one of said cars to said first one of said cars via said first and second antennae by free space electromagnetic wave coupling; a first housing mounted on said first one of said cars for housing said first antenna; and a second housing mounted on said second one of said cars for housing said second antenna; characterized in that said first and second electromagnetic wave signals are of radio frequency; Ssaid first housing includes a first RF shielding means surrounding said first antenna; said second housing includes a second RF shielding means surrounding said second antenna; said first housing and said second housing each comprise an open end through which an RF signal may pass; and said first and second housings are mounted such that in use the open end of the first housing faces the open end of the second housing whereby RF signals may pass 20 between aid housings through said open end of each of said first and said second housings, while the sending or receiving of extraneous RF signals from an outside of said housings and an inside of said housings is •substantially prevented.

25 BRIEF DESCRIPTION OF DRAWINGS The invention will be better understood by an examination of the following description, together with the accompanying drawings, in which: I- R i PCIIIIIC 71 9- FIGURE I. is a schematic drawing illustrating two back-to-back cars of a train, the radio link between the cars, and the circuits linked by the radio links; FIGUIRE 2 illustrates in greater detail a Train Line Multiplexer (TMX); FIGURES 3A and 3B illustrate two modulation approaches for the transmitters of the radio link transceiver (RLT); FIGURE 4 illustrates a particular embodiment of the RLT receiver; FIGURE 5 illustrates a duplexer arrangement constituting a part of the RLT; and FIGURE 6 illustrates in greater detail the radio link between the end cars.

DESCIPTION OF-PREV t ELRED EMBODIMENTS As seen in Figure 1, a free space communication link 15 permits communications between cars 3 and 5. Each car includes a In line multiplexer (TMX) 17' and 17'' and a rciolink transceiver (RLT) 19' and 19''.

As seen in Figure 2, the multiplexer 17 will receive digital signals of samples from different train systems, for example, monitoring system 21, brake system 23, propulsion system ventilation system 27 and intercom system 29. These signals are arranged in a predetermined order to form a frame which can be, for example, 125 10 microseconds long. As can be seen, each frame includes a frame synchv .zation signal. at the beginning of the frame.

Those signals 'are then passed to the -transmitter which transmits them, via the communications link, to a different, usually adjacent, train car.

At the receiving end, the demultiplexer will provide the digital signals to the various trains systems, that is, the monitoring system 21, the brake system 23, the propulsion system 25, the ventilation system 27 and the intercom system 29..

Multiplexing and demultiplexing systems are, of course, well known in the art so that no f urther description is required.

The output of the TMX is, as seen in Figures 3A and 3B, fed to the modulation unit of the 0 .0 *RLT. Figure SA illustrates a direct modulation unit while Figure 5B illustrates an indi-rect modulation 00: 20 unit. Each unit includes a line interface (31 or 41) and a signal processor (33 or 43). These units process the signals to put them into condition f or use -in the modulator. Thus, if there are a long string of zeros in the signals, then the signals must b e modified to include ones and zeros, and such modification will take place in the units 31, 41 and .5 33, 43.

Referring now to Figure 3A, the output of the signal processor 33 is fed to a modulator 37 which has *a second input terminal f ed by an RB' generator 35. The output of the modulator is fed to a bandpass filter 39, and the output of the filter is fed to a duplexer circuit illustrated in F'igure 11 Turning to Figure 3B, the output of the signal processor 43 is once again fed to a modulator 47. However, in this case, the second terminal of modulator 47 is fed from IF source 45. The output of the modulator 47 is once again passed through. a bandpass filter 49, the output of the filter 49 is fed to a mixer 53. The second input terminal of mixer 53 is fed from an RF generator 51, and the output of mixer 53 is fed to bandpass filter, The output of bandpass filter 55 is once again fed to the duplexer circuit.

Figure 4 illustrates one embodiment of the receiver portion of the RLT. The output of the duplexers circuit is fed to a bandpass filter 57 whose output is fed to a mixer 59. The received signal is then mixed with an RF signal from RF generator 61 applied to the second terminal of the mixer 59. The output of the mixer is fed to a bandpass filter 63 whose output is fed to a demodulator 65. The synchr6nization signal is fed from the demodulator 65 to symbol and bit clock recovery circuit 67, and the output of both 65 and 67 are fed to signal processor 69. The output of 69 is fed to line interface 71 whose output is then fed to the TMX.

Figure 5, which illustrates the duplexer 77, and the transmitter 73 and the receiver 75 is self-explanatory.

Turning now to Figure 6, the free space electromagnetic link 15 between car 7' and car 7'' is effected by RF antennas 83' and 83"' respectively. In a particular embodiment, the antennas are mounted in housings 79' and 79'', respectively, which housings are made of a 12 dielectric material, for example, polycarbonate material.

Each housing comprises a sealed enclosure which protects the antenna from humidity and water damage.

Disposed around the housing 79' and 79'' are metallic shields 81' and As can be seen, the shields do not extend across the front of the housings 79' and 79'' (that is, the parts of the housings facing each other) but do extend around the antennas to prevent a spurious dispersion of the RF signals from the antennas 83' and 83'' in any direction from one car to another car, and do not allow the antennas to pick up any spurious electromagnetic signals except those originating from the other end car.

The shields also include conductor elements 85' and o 0.

85" to prevent backward transmission or reception from the rear. Connector cables 87' and 87'' connect the antennas to the RLT units of their respective cars.

The couplers are mounted on the exterior of the car and, when the cars are coupled to each other, are physically close to each other. They are sealed against 0 water and humidity and protected from flying stones both by the housing 79' and 79'' and the shields 81' and 81''.

25 Although the housings illustrated in Figure 6 would be necessary for a particular type of antenna, if the antennas are small enough, then they would not have to be protected by such a housing. In fact, in some situations, it might be possible to mount the housings inside of the cars. Accordingly, the housing is for a particular situation.

The present inventive arrangement is not subject to the physical disadvantages of the pin and spring arrangements, and they are not affected by the fact that they have to operate in a dirty environment.

Although a particular embodiment has been described, this was for the purpose of illustrating, but not limiting, the invention.

o* so e *ooo* es

AAL,.

Claims

1. A communication link I'r permitting communications between adjacent cars of a multi-car vehicle, said link comprising: on at least a first one of said cars, a first multiplexing/demultiplexing means for multiplexing first digital signals representative of the status or control signals of various systems on said first one of said cars, and for processing said first digital signals into a first digital trainline signal; (ii) first means for converting said first digital trainline signal to a first electromagnetic wave signal; and o: 15 (iii) a first antenna mounted on one end of said first one of said cars for transmitting said first electromagnetic wave signal; in use said first multiplexing/demultiplexing means converting a second electromagnetic wave signal into a second digital trainline signal to provide second digital signals representative of the status or control signals of various systems on a second one of said cars and said first antenna receiving said second electromagnetic wave signal; on said second one of said cars a second multiplexer/demultiplexer means I I for multiplexing said second digital signals, and for processing said second digital signals into a second digital trainline signal; (ii) second means for converting said second digital trainline signal to a second electromagnetic wave signal; and (iii) a second antenna mounted on said second one of said cars at an end thereof adjacent to the end of the first car on which said first antenna is mounted; in use said second antenna transmitting said second o electromagnetic wave signal; said second e multiplexing/demultiplexing means converting said first electromagnetic wave signal into a first digital trainline signal to provide first digital signals representative of the status or control signals of various systems on said first one of said cars; and said second antenna receiving said first electromagnetic wave 0.0 o signals; whereby communications can be sent from'said first one of said cars to said second one of said cars and from said second one of said cars to said first one of said cars via said first and second antennae by free space electromagnetic wave coupling; a first housing mounted on said first one of said cars for housing said first antenna; I, r r 16 and a second housing mounted on said second one of said cars for housing said second antenna; characterized in that said first and second electromagnetic wave signals are of radio frequency; said first housing includes a first RF shielding means surrounding said first antenna; said second housing includes a second RF shielding means surrounding said second antenna; said first housing and said second housing each comprise an open end through which an RF signal may pass; and said first and second housings are mounted such that in use the open end of the first housing faces the open end of the second housing whereby RF signals may pass .between said housings through said open end of each of said first and said second housings, while the sending or receiving of extraneous RF signals from an'outside of said housings and an inside of said housings is substantially prevented.

2. A link as defined in claim 1 wherein said multiplexing means on said first one of said cars can also perform the function of a Ir 17 demultiplexer; and wherein the demultiplexer on said second one of said cars can also perform the function of a multiplexer; said first one of said cars also including a means for receiving and said second one of said cars also including a means for transmitting whereby, communications can be sent from said first one of said cars to said second one of said cars and from said second one of said cars to said first one of said cars. 9

3. A link as defined in claim 2 wherein said first one a of said cars and said second one of said cars "f 15 comprise adjacent cars in said a multi-car vehicle.

4. A link as defined in claim 2 or 3 wherein said open end comprises a dielectric material window. S 20

5. A link as defined in claim 1, 2, 3 or 4 wherein said shielding means include conductor elements to prevent backward transmission or receiption from the rear. Dated this 19th day of August 1997 PRIMETECH ELECTRONIQUES INC. Patent Attorneys for the Applicant T F B RICE CO TRAINLINE SYSTEM USING AN ELECTROMAGNETIC COMMUNICATION LINK Abstract of the Disclosure The link permits communications between cars of a railway or subway trains. On at least a first one of the cars, a multiplexer multiplexes digital signals representative of the status of various systems on the car, and processes them into a first digital trainline signal. A transmitter includes a modulator which converts the digital trainline signal to a RF signal, and the RF signal is transmitted, by an antenna, through free space OS"from the first car to a second car. The second car •includes an antenna for receiving the RF signal, and a receiver for de-modulating the signal and converting it to a second digital trainline signal. off* A demultiplexer demultiplexes the second digital trainline signal into appropriate formats readable by the train systems on board the second car. Both the first and second cars include multiplexers and demultiplexers, and transmitters and receivers, so that communication is possible between the first car and the-second car as well as between the second car and the first car.