WO2012009754A1

WO2012009754A1 - Communication system

Info

Publication number: WO2012009754A1
Application number: PCT/AU2011/000913
Authority: WO
Inventors: Grant Wilmot; Brad Flint; Jason Coleman
Original assignee: Minetec Wireless Technologies Pty Ltd
Priority date: 2010-07-19
Filing date: 2011-07-19
Publication date: 2012-01-26

Abstract

A communication system (20), the system comprising a headend (21), a modem (22), and a leaky feeder cable (23) through which the headend (21) and the modem (22) are able to transmit communication signals to each other.

Description

COMMUNICATION SYSTEM

Field of the Invention

The present invention relates generally to a data communication system and, in particular, to a broadband data communication system.

Although the present invention will be described with particular reference to being used to provide broadband Ethernet connectivity in an underground mining environment, it will be appreciated that it is not necessarily limited to being used in this particular manner.

Background Art

Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference, which means that it should be read and considered by the reader as part of this text. That the document, reference, patent application or patent cited in this text is not repeated in this text is merely for reasons of conciseness.

The following discussion of the background to the invention is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge of the person skilled in the art in any jurisdiction as at the priority date of the invention.

There is a need in some underground mining environments to have sophisticated broadband data communication systems. In particular, there is a need in some underground mining environments to have communication systems which provide broadband Ethernet connectivity.

Existing communication systems which provide broadband Ethernet connectivity in underground mining environments include conventional distributed fibre-optic or copper underground Ethernet networks. However, there can be a significant cost to install and maintain these networks because they are usually separate from other communication systems, such as leaky feeder communication systems, which are often used in underground mining environments to provide services such as voice and/or basic telemetry communication services. To try and reduce the costs associated with providing broadband Ethernet connectivity in underground mining environments which may already have a leaky feeder communication system installed, or in which such a system is to be installed, various attempts have been made to modify those leaky feeder communication systems so that they provide broadband Ethernet connectivity. An example of such a system is the Varis™ Smart Com™ leaky feeder and Ethernet communications system.

A typical leaky feeder communication system includes a leaky feeder cable which is in the form of a coaxial cable which is run along a tunnel or shaft, and which emits and receives electromagnetic RF (radio frequency) communication signals, on an upstream channel of approximately 1 50 MHz and a downstream channel of approximately 170 MHz. The cable is leaky in that it has gaps or slots in its outer conductor which are located along the length of the cable. The gaps or slots allow electromagnetic RF signals to leak into or out of the cable along its length. It is this leakage which enables the leaky feeder communication system to be used to communicate with mobile radio units in an off air manner which are located in the vicinity of the cable. As a consequence of the signal leakage, leaky feeder line amplifiers typically need to be inserted at regular intervals along the length of the cable to boost the signal back up to acceptable levels. Line amplifiers in service today typically only accommodate these existing upstream and downstream channel requirements.

Existing fundamental Ethernet over coax technology has upstream channels typically limited to the range of 5 - 65 MHz and downstream channels limited to the range of 88 - 860 MHz. Existing Ethernet over leaky feeder technology, as supplied by other vendors, attempts to modify the fundamental Ethernet over coax upstream and downstream channels to fit within the preexisting upstream and downstream channel range of the leaky feeder line amplifiers mentioned.

Existing fundamental Ethernet over coax technology has been tested to be susceptible to narrow band, high level carrier inputs, typical of existing voice and/or basic telemetry communications services running within existing leaky feeder installations. Existing fundamental Ethernet over coax technology is also susceptible to varying RF environmental conditions such as the noise floor, line attenuation and group delay. It is against this background that the present invention has been developed.

Summary of the Invention

It is an object of the present invention to overcome, or at least ameliorate, one or more of the deficiencies/obstacles of the prior art mentioned above, and/or to provide the consumer with a useful and/or commercial choice.

Other objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, a preferred embodiment of the present invention is disclosed.

According to a first broad aspect of the present invention, there is provided a communication system, the system comprising a headend, a modem, and a leaky feeder cable through which the headend and the modem are able to transmit communication signals to each other.

Preferably, the communication system is a broadband data communication system.

Preferably, the headend is an Ethernet headend, and the modem is an Ethernet modem.

Preferably, the headend and the modem are able to transmit communication signals to each other through the leaky feeder cable using an upstream RF (radio frequency) channel and a downstream RF channel. It is preferred that the upstream RF channel has a carrier frequency of about 60 MHz, and that the downstream RF channel has a carrier frequency of about 125 MHz. It is also preferred that the upstream RF channel has a bandwidth of about 13 MHz, and that the downstream RF channel has a bandwidth of about 30 MHz.

Preferably, communication signals of other communication services are also able to be transmitted through the leaky feeder cable. For example, communication signals of voice and/or telemetry communication services may be transmitted through the leaky feeder cable.

It is preferred that the communication signals of those other communication services are able to be transmitted through the leaky feeder cable using an additional upstream RF channel, and an additional downstream RF channel. Preferably, the additional upstream RF channel has a carrier frequency of about 150 MHz, and the additional downstream RF channel has a carrier frequency of about 170 MHz.

Preferably, the leaky feeder cable is a coaxial cable. It is also preferred that the leaky feeder cable is part of a leaky feeder communication system. The leaky feeder communication system may be an existing leaky feeder communication system. For example, the leaky feeder communication system may be an existing leaky feeder communication system which is able to provide or already providing voice and/or basic telemetry communication services.

Preferably, the system also includes an interface which interfaces the headend or the modem to the leaky feeder cable.

Preferably, the system also includes at least one amplifier for amplifying any and/or all communication signals which are transmitted through the leaky feeder cable.

According to a second broad aspect of the present invention, there is provided a method for providing a communication system, the method comprising the steps of:

connecting a headend to a leaky feeder cable; and

connecting a modem to the leaky feeder cable, wherein the headend and the modem are connected to the leaky feeder cable such that the headend and the modem are able to transmit communication signals to each other through the leaky feeder cable.

Preferably, the method is for providing a broadband data communication system.

Preferably, the steps of connecting a headend and a modem to the leaky feeder cable respectively include connecting an Ethernet headend and an

Ethernet modem to the leaky feeder cable.

Preferably, the step of connecting the headend or the modem to the leaky feeder cable includes the step of interfacing the headend or the modem to the leaky feeder cable with an interface.

Preferably, the method also includes the step of amplifying communication signals from an ELF (Ethernet over Leaky Feeder) system and voice and/or basic telemetry communication services which are transmitted through the leaky feeder cable. According to a third broad aspect of the present invention, there is provided a headend adapted to communicate with a modem through a leaky feeder cable.

Preferably, the headend is an Ethernet headend.

According to a fourth broad aspect of the present invention, there is provided a modem adapted to communicate with a headend through a leaky feeder cable.

Preferably, the modem is an Ethernet modem.

According to a fifth broad aspect of the present invention, there is provided an interface adapted to interface a headend or a modem to a leaky feeder cable.

Preferably, the interface is adapted to interface an Ethernet headend or an Ethernet modem to the cable.

According to a sixth broad aspect of the present invention, there is an amplifier to amplify communications signals between a headend and a modem via the leaky feeder cable.

Preferably, the amplifier amplifies all communications signals for both of the voice and/or basic telemetry communication services and the broadband data communication system.

Brief Description of the Drawings

In order that the invention may be more fully understood and put into practice, a preferred embodiment thereof will now be described with reference to the accompanying drawings, in which:

Figure 1 depicts a communication system according to a preferred embodiment of the present invention.

Figure 2 depicts the upstream and downstream RF channels of the communication system;

Figure 3 depicts a block diagram of significant equipment pertaining to a headend of the communication system ;

Figure 4 depicts a block diagram of functional components of an ELF modem;

Figure 5 depicts a block diagram of functional components of a headend interface module; Figure 6 depicts a block diagram of functional components of an ELF modem interface board; and

Figure 7 depicts a block diagram of functional components of an ELF dual, bi-directional amplifier.

Best Mode(s) for Carrying out the Invention

Referring to figure 1 , there is a communication system 20 according to a preferred embodiment of the present invention. System 20 provides Ethernet connectivity which allows computers to communicate with each other in an underground mining environment.

System 20 includes an Ethernet headend in the form of an ELF (Ethernet over Leaky Feeder) headend 21 , one or a plurality of ELF dual band bidirectional amplifiers 26 and one or a plurality of Ethernet modems that are each in the form of an ELF (Ethernet over Leaky Feeder) modem 22, and a leaky feeder cable in the form of a leaky coaxial cable 23 through which the headend 21 and modems 22 are able to transmit communication signals to each other.

Headend 21 and modems 22 are typically located at various physical locations which are remote from each other. Modems 22 are placed at various locations in the underground mining environment where Ethernet connectivity is to be provided.

Headend 21 and modems 22 are connected to the cable 23 by a plurality of interfaces or devices 24 and 26 so that the headend 21 and modems 22 are able to communicate with each other by transmitting communication signals through or via the cable 23.

Cable 23 includes a plurality of gaps or slots (not depicted) located along its length so that electromagnetic RF communication signals are able to leak into and out of the cable 23. This signal leakage allows radio transceivers such as mobile radio transceivers which are in the vicinity of the cable 23 to communicate using the system 20.

System 20 also includes one or more amplifiers 26 for amplifying the communication signals which are transmitted through the cable 23 so as to maintain those signals at an acceptable level despite the signal leakage from the cable 23.

Ethernet data which is transmitted between the headend 21 and the modems 22 by the communications signals which are transmitted through the cable 23 and amplifiers 26 is able to flow into and out of the system 20 through the headend 21 and the modems 22 as indicated by the arrows 25.

With reference to figure 2, communication signals are able to be transmitted through the cable 23 from the modems 22 to the headend 21 using a first or upstream RF channel 70 which has a carrier frequency of about 60 MHz, and a bandwidth of about 13 MHz. Communication signals are able to be transmitted through the cable 23 from the headend 21 to the modems 22 using a second or downstream RF channel 71 which has a carrier frequency of about 125 MHz, and a bandwidth of about 30 MHz.

In addition to Ethernet data 25 being transmitted by communication signals 70, 71 through the cable 23, other information or data which are part of other communication services such as voice and/or telemetry communication services are able to be transmitted by other communication signals 72, 73 through the cable 23, devices 24 and amplifiers 26.

Information or data such as voice and/or telemetry information or data which are part of other communication services are also available to be transmitted by other communication signals 72, 73 through the cable 23, devices 24 and amplifiers 26 of the leaky feeder communication system 20 using a second or additional upstream RF channel 72 and a second or additional downstream RF channel 73. The additional upstream RF channel 72 has a carrier frequency of about 150 MHz, and the additional downstream RF channel 73 has a carrier frequency of about 170 MHz.

The leaky feeder cable 23 may be part of an existing leaky feeder communication system in an underground mine which has been modified/retrofitted to provide Ethernet connectivity.

The system 20 includes the ELF headend 21 which according to a preferred embodiment of the present invention is depicted in figure 3. ELF headend 21 provides the central processing and connection negotiation for all ELF modems 22. Herein conventional voice and/or telemetry communication services 31 signals 72, 73 are passed through a leaky feeder headend 33. A modem headend 30 is interfaced to the leaky feeder headend 33 via an interface module 32. The modem headend 30 modulates Ethernet at various modes and frequencies, then the headend interface module 32 filters the transmission and then amplifies the signal to be sent through the leaky feeder headend 33. The leaky feeder headend 33 then combines all communications signals 70, 71 , 72 and 73 into the leaky feeder cable 23 for distribution through the communication system 20.

ELF headend 21 includes a headend interface module 32 which interfaces the modem headend 30 with the leaky feeder headend 33. A block diagram depicting the major functional blocks of the headend interface module 32 is depicted in figure 5.

The headend interface module 32 is designed and operable to filter the unwanted noise and other services 72, 73 from the RF communication signals

70, 71 which are transmitted along the leaky feeder cable 23. Downstream communications signals 71 are interfaced to the headend interface module via RF connectors 40 and passed through filters 42 and amplifier 41 then into the leaky feeder headend 33 via another RF connector 40. Upstream communications signals 70 are passed from the leaky feeder headend 33 into the headend interface module 32 via RF connectors 40 and passed through filters 44 and amplifier 45 then interfaced to the modem headend 30 via another RF connector 40.

ELF dual band, bi-directional amplifier(s) 26 provide the means of transporting all ELF relevant RF data 70, 71 over the leaky feeder network 23, 24 as well as passing all conventional mine voice and telemetry data 72, 73. An ELF dual band bi-directional amplifier 26 has internal control signals and diagnostic signaling that communicates to the ICU (headend 21 ) and the ELF modems 22. The dual band bi-directional amplifier 26 preferably has upstream and downstream pass bands/bandwidths and carrier frequencies as depicted in figure 2.

A preferred embodiment of the ELF dual band bi-directional amplifier 26 is depicted in figure 7. The ELF dual band bi-directional amplifier 26 is designed and operable to provide leaky feeder 23 and device 24 line loss compensation for all communications signals pertaining to both voice and/or telemetry data and ELF Ethernet data signals 70, 71 , 72 and 73. Downstream communications signals for both conventional voice and data services and ELF Ethernet signals

71 , 73 are passed into the ELF dual band bi-directional amplifier 26 via leaky feeder termination point 51 , split 52 and passed through filters 53 and 55, then line level compensated via amplifiers 54 and 56. Downstream signals 71 and 73 are then combined 52 and interfaced back onto the leaky feeder cable 23 via leaky feeder termination point 51 . Upstream communications signals for both conventional voice and data services and ELF Ethernet signals 70, 72 are passed into the ELF dual band bi-directional amplifier 26 via leaky feeder termination point 51 , split 52 and passed through filters 58 and 60, then line level compensated via amplifiers 57 and 59. Upstream signals 70 and 72 are then combined 52 and interfaced back onto the leaky feeder cable 23 via leaky feeder termination point 51 .

System 20 includes an ELF modem 22 which according to another preferred embodiment of the present invention is depicted in figure 4. Communications signals 70, 71 and DC power are delivered to the modem 22 via the leaky feeder cable 23. Modem interface board 108 both filters out noisy signals 72, 73 and provides clean power for the modem 107. The modem 107 then converts the incident communications signals 70, 71 into Ethernet data 25.

ELF interface board 108 within ELF modem 22 is designed and operable to filter the unwanted noise and other services 72, 73 from the RF communication signals 70, 71 which are transmitted along the leaky feeder cable 23, separate the RF signals 70, 71 , 72, 73 from the DC (direct current) signals, supply DC to the modem 107, and amplify the output signals 70 of the modem

107 to the correct amplitude required for the system 20. Modem interface board

108 includes functional components 102, 103, 104, 105,106, 109, 1 10 and 1 1 1 . Components 102 and 103 process the downstream channel 71 , and components 104 and 105 process the upstream channel 70. Components 102 and 105 remove unwanted noise and other services 72, 73 from the RF signals 70 and 71 and separate the two RF carrier frequency signals of the upstream and downstream channels 70, 71 from the leaky feeder cable. Components 103 and 104 reduce and amplify the RF signals to the correct levels required by the system 20. Component 106 converts the DC voltages required for the modem 107 and amplifiers 103 and 104. Components 109 both split and combine ELF communications signals 70 and 71 . Component 1 1 1 provides an RF connector to the Ethernet modem 107 and component 1 10 provides the interface to the leaky feeder cable 23 via a leaky feeder termination point.

ELF modem 107 is connected to the leaky feeder cable by the ELF interface board 108 and provides the Ethernet 'endpoint'. Modem 107 negotiates with the headend 21 and provides Ethernet connectivity to the surface. Modem 107 is fitted with diagnostic modules that communicate with the ICU/headend 21 and amplifiers 26.

Interface 108 may be physically separate from the headend 21 and/or the modem 22, 107, or they may be incorporated into the headend 21 and/or modem 22, 107.

The modem headend 21 of the system 20 is a DOCSIS (Data Over Cable Service Interface Specification) headend. Typically, the headend 21 will be shielded to prevent the RF signals which leak from the leaky cable interfering with its operation via the headend interface board 32.

The To' services and 'From' services of the cable modems 22, 107 will also typically be protected/shielded to protect against interference from the RF signals which leak from the leaky cable. Unlike a CMTS (Cable Modem Termination System) which are meant for use in a 'clean' (i.e. low RF noise) rather than a 'dirty' (i.e. high RF noise) environment, and which are susceptible to noise, the modem 22 can be used in 'dirty' RF environments.

The clean signal which is transmitted between the headend 21 and the cable modem 22 has a balance point which is set well above the noise floor. The balance point drops down just before the signal reaches the cable modem 107.

System 20 provides a means of delivering broadband Ethernet connectivity throughout a tunneled underground mining environment utilising a new and/or an existing distributed leaky feeder network. The technology can coexist with both existing and future radio frequency (RF) services (e.g. voice and/or telemetry services) on the network and is tailored specifically to work with current underground mining system design practices.

The embodiment of the present invention provides a workable implementation of a leaky feeder communication system which has Ethernet connectivity, and can achieve higher bandwidths and a better utilisation of technology over a given leaky feeder transport medium/system.

These advantages are achieved by using an easy to install and maintain backbone network. The system according to the present invention utilises/operates over a leaky feeder cable, a standard for underground mining communications. With embodiments of the present invention, only a relatively small additional cost is required to provide a premium broadband network which utilises leaky feeder communication system network infrastructure which generally already has an allocated budget and which is commonly only utilised for voice and low-level telemetry applications.

An advantage of the present invention compared to the Varis™ Smart Com™ product is that the present invention, unlike that product, does not include a 'CMTSI' (Cable Modem Terminated System Interface). Another advantage of the present invention is the design of its dual band, bi-directional amplifiers.

Another advantage of the system according to the present invention is that it is scalable and upgradable as the radio technology is implemented, adapts and evolves.

The present invention may be applied wherever there is an underground leaky feeder distribution network such as in mine tunnels, train tunnels and the like.

By using the present invention in a mine, the user is able to pass any mine specific Ethernet traffic throughout the mine and provide the facility to remotely monitor and/or control devices underground from the surface. These may include but not be limited to video, PLC monitoring and control, or office and mine management orientated data transfers.

It will be appreciated by those skilled in the art that variations and modifications to the invention described herein will be apparent without departing from the spirit and scope thereof. The variations and modifications as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.

Throughout the specification and claims, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Throughout the specification and claims, unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

I . A communication system, the system comprising a headend, a modem, and a leaky feeder cable through which the headend and the modem are able to transmit communication signals to each other.

2. The system of claim 1 , wherein the communication system comprises a broadband data communication system.

3. The system of claim 1 or 2, wherein the headend comprises an Ethernet headend, and the modem comprises an Ethernet modem.

4. The system of any one of the preceding claims, wherein the headend and the modem are able to transmit communication signals to each other through the leaky feeder cable using an upstream RF (radio frequency) channel and a downstream RF channel.

5. The system of claim 4, wherein the upstream RF channel has a carrier frequency of about 60 MHz.

6. The system of claim 4 or 5, wherein the downstream RF channel has a carrier frequency of about 125 MHz.

7. The system of any one of claims 4 to 6, wherein the upstream RF channel has a bandwidth of about 13 MHz.

8. The system of any one of claims 4 to 7, wherein the downstream RF channel has a bandwidth of about 30 MHz.

9. The system of any one of the preceding claims, wherein communication signals of other communication services are also able to be transmitted through the leaky feeder cable.

10. The system of claim 10, wherein communication signals of voice and/or telemetry communication services are able to be transmitted through the leaky feeder cable.

I I . The system of claim 10 or 1 1 , wherein the communication signals of the other communication services are able to be transmitted through the leaky feeder cable using an additional upstream RF channel, and an additional downstream RF channel.

12. The system of claim 1 1 , wherein the additional upstream RF channel has a carrier frequency of about 150 MHz, and the additional downstream RF channel has a carrier frequency of about 170 MHz.

13. The system of any one of the preceding claims, wherein the leaky feeder cable comprises a coaxial cable.

14. The system of any one of the preceding claims, wherein the leaky feeder cable comprises part of a leaky feeder communication system.

15. The system of claim 14, wherein the leaky feeder communication system is an existing leaky feeder communication system.

16. The system of claim 15, wherein the leaky feeder communication system is an existing leaky feeder communication system which is able to provide or already providing voice and/or basic telemetry communication services.

17. The system of any one of the preceding claims, comprising an interface which interfaces the headend or the modem to the leaky feeder cable.

18. The system of any one of the preceding claims, comprising at least one amplifier for amplifying any and/or all communication signals which are transmitted through the leaky feeder cable.

19. A method for providing a communication system, the method comprising:

connecting a headend to a leaky feeder cable; and

connecting a modem to the leaky feeder cable, wherein the headend and

the modem are connected to the leaky feeder cable such that the headend and the modem are able to transmit communication signals to

each other through the leaky feeder cable.

20. The method of claim 20, wherein the method is for providing a broadband data communication system.

21 . The method of claim 19 or 20, wherein connecting a headend and a modem to the leaky feeder cable respectively include connecting an

Ethernet headend and an Ethernet modem to the leaky feeder cable.

22. The method of any one of claims 19 to 21 , wherein connecting the headend or the modem to the leaky feeder cable includes interfacing the headend or the modem to the cable with an interface.

23. The method of any one of claims 19 to 22, comprising amplifying communication signals from the ELF system and voice and/or basic telemetry communication services which are transmitted through the leaky feeder cable.

24. The method of any one of claims 19 to 23, further comprising connecting an amplifier between leaky feeder cable paths providing communication between the headend and the modem.

25. A headend adapted to communicate with a modem through a leaky feeder cable.

26. The headend of claim 25, wherein the headend is an Ethernet headend.

27. A modem headend interface module to adapt a headend to interface to a leaky feeder cable.

28. A modem adapted to communicate with a headend through a leaky feeder cable.

29. The modem of claim 28, wherein the modem is an Ethernet modem.

30. A modem interface board to enable a modem to interface to a leaky feeder cable.

31 . An interface adapted to interface a headend or a modem to a leaky feeder cable.

32. The interface of claim 31 , wherein the interface is adapted to interface an

Ethernet headend or an Ethernet modem to the leaky feeder cable.

33. An amplifier to line level compensate communication signals for voice and/or basic telemetry communication services which are transmitted through a leaky feeder cable.

34. The amplifier of claim 33, wherein the amplifier amplifies all communications signals for both of the voice and/or basic telemetry communication services and the broadband data communication system.

35. An amplifier to amplify communications signals between a headend and a modem via a leaky feeder cable.

36. A dual band bi-directional amplifier to line level compensate communication signals for voice and/or basic telemetry communication and ELF board band data services which are transmitted through a leaky feeder cable.

37. A communication system substantially as hereinbefore described with reference to the accompanying drawings.

38. A method for providing a communication system substantially as hereinbefore described with reference to the accompanying drawings.