WO2010039680A1

WO2010039680A1 - Method for transitioning from wide band to narrow band radios

Info

Publication number: WO2010039680A1
Application number: PCT/US2009/058725
Authority: WO
Inventors: Mark Uehling; Ravi Goonasekeram
Original assignee: Wabtec Holding Corp.
Priority date: 2008-10-01
Filing date: 2009-09-29
Publication date: 2010-04-08

Abstract

A method for transitioning from wide band to narrow band EOT and/or LCU radios includes providing an EOT radio and/or an LCU radio having at least one filter in a radio receiver section that determines receiver bandwidth. The at least one filter provides a usable bandwidth that allows wide band reception for transmissions having a modulation level of about 3.0 kHz. Next, the at least one filter is removed and replaced with at least one new filter that provides a usable bandwidth that allows reception for transmissions having a modulation level of either 2.5 kHz or 3.0 kHz. The receiver section with the at least one new filter is thereby configured to receive transmissions with minimal signal distortion and degradation in either a narrow band or a wide band environment.

Description

METHOD FOR TRANSITIONING FROM WIDE BAND TO NARROW BAND RADIOS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001]. This application is based on United States Provisional Patent Application No. 61/101,761, filed October 1, 2008, on which priority of this patent application is based and which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

[0002] The present invention generally relates to railroad telemetry radios and, more particularly, to railroad telemetry radios able to transmit and receive with minimal signal-to-noise degradation when a narrow band transceiver communicates with a wide band transceiver and vice versa. Description of Related Art

[0003] Locomotive Control Unit (LCU) radios (also known as Head of Train (HOT) radios) and End of Train (EOT) radios (generally known as railroad telemetry radios) are complementary devices which communicate with each other as part of a complete information and control system to be used on freight trains as required by the Federal Railway Administration (FRA). The EOT unit, which includes the EOT radio, is typically mounted on the last car of the train in the place of a caboose. The EOT unit performs three principal functions. First, it monitors various operating conditions of the train including air pressure in the brake line, battery condition, marker light condition, motion, and emergency valve status. Second, the EOT unit transmits the information it monitors to a lead locomotive so that informed command and control decisions may be taken. Finally, the EOT unit provides the ability to vent air from the brake pipe at the rear of the train in the event of an emergency. The information monitored by the EOT is then transmitted via a radio frequency (RF) link to the LCU and is displayed to the crew in the locomotive.

[00Θ4] The LCU/EOT pair uses two frequencies. The EOT transmits on one and the LCU on the other. All North American LCUs and EOTs use the same frequencies. The LCU always transmits on 452.9375 Mhz and the EOT always transmits on 457.9375 Mhz. This is possible because both LCUs and EOTs only transmit short messages and typically only transmit once every couple minutes. In addition, most of the time trains are not in close proximity to one another, except in freight yards. [0005] [0006] Federal regulations require that by January 1, 2013, EOT and LCU radios communicate in channels separated by only 12.5 kHz (narrow band) in frequency in order to allow for more communications channels. This change, however, presents significant logistical and cost problems for the railroads that already have thousands of wide band radios (i.e., radios that communicate in channels separated by 25 kHz) in service. Radio devices designed for wide band operation do not communicate well with radio devices designed for narrow band operation. More specifically, most of the currently used wide band or narrow band radios have a corresponding wide or narrow receive filter designed to optimize receive performance for those signals. Typically, a narrow band radio would be designed with a narrow band receiver as this gives the best reception of a narrow band signal because it attenuates signals outside of the narrow channel increasing signal-to-noise ratio of the received signal. However, when a wide band signal is received through this narrow band filter, it gets distorted because some of the signal information is outside of the narrow band of the receive filter and gets attenuated. This makes the signal harder to decode and the message may be lost. Likewise, when a narrow band signal is received through a wide band filter, less band noise is attenuated, so there is a reduction in signal-to-noise ratio and hence a reduction in reception range.

[0007] In order to solve this problem, radios have been developed that have both wide and narrow band receivers that can be switched to optimize receiver performance for a wide or narrow band signal. While such radios allow for the reception of either wide or narrow band signals, the receiver does not know ahead of time what type of signal it will be receiving in the case of LCU or EOT radios. If the receiver is set for a wide band filter and a narrow band signal is received, the signal may not be "heard" because the filter is not set correctly for that signal. Long trains are at the limits of the LCU to EOT radio reception range, so a significant decrease in signal-to-noise ratio can not be tolerated.

[0008] Accordingly, a need exists for railroad telemetry radios that are able to transmit and receive with minimal signal-to-noise degradation when a narrow band transceiver communicates with a wide band transceiver and vice versa. This would allow the railroad companies to gradually introduce narrow band capable radio devices into the market, while still interoperating well with existing devices.

SUMMARY OF THE INVENTION

[0009] The present invention provides railroad telemetry radios that are able to transmit and receive with minimal signal-to-noise degradation when a narrow band transceiver communicates wilh a wide band transceiver and vice versa. In addition, the present invention does not require that the receiver know ahead of time the type of signal to be detected. [0Θ10J Accordingly, the present invention provides a receiver capable of operating with minimal distortion and loss of signal-to-noise ratio when receiving both modulation levels (i.e., 3.0 kHz or 2.5 kHz or less). This method allows the reception of both wide and narrow band radio transmissions with minimal degradation of signal quality.

[0011] The present invention is directed to a method for transitioning from wide band to narrow band EOT and/or LCU radios. The method includes the step of providing an EOT radio and/or an LCU radio having at least one filter in a radio receiver section that determines receiver bandwidth. The at least one filter provides a usable bandwidth that allows wide band reception for transmissions having a modulation level of about 3.0 kHz. Next, the at least one filter is removed and replaced with at least one new filter that provides a usable bandwidth that allows reception for transmissions having a modulation level of either 2.5 kHz or 3.0 kHz. The receiver section with the at least one new filter is thereby configured to receive transmissions with minimal signal distortion and degradation in either a narrow band or a wide band environment.

[0012] The modulation level and the data rate determine the bandwidth of a transmission. The at least one new filter may be chosen such that the bandwidth of the new filter can pass a signal deviating at 3.0 kHz or 2.5 kHz with minimal distortion. For instance, the new filter may be a CFUKG455KD4A-RO mid-band filter made by Murata Corporation, or any other suitable filter. The EOT radio may be configured to be attached to a last car of a train. The LCU radio may be configured to be installed in a lead locomotive of a train. [0013] The present invention is also directed to a radio telemetry system for use with a locomotive control system of a train. The radio telemetry system includes an EOT unit attached to a last car of the train and an LCU installed in a lead locomotive of the train. The EOT unit includes an EOT radio having a radio receiver section with a filter that provides a usable bandwidth that allows reception for transmissions having a modulation level of either 2.5 kHz or 3.0 kHz. The LCU includes an LCU radio having a radio receiver section with a filter that provides a usable bandwidth that allows reception for transmissions having a modulation level of either 2.5 kHz or 3.0 kHz. The EOT radio and the LCU radio are thereby configured to receive transmissions with minimal signal distortion and degradation in either a narrow band or a wide band environment.

[0014] The modulation level and the data rate determine the bandwidth of a transmission. The filters of the EOT radio and the LCU radio may be chosen such that the bandwidth of the filters can pass a signal deviating at 3.0 kHz or 2.5 kHz with minimal distortion. For instance, the filters may be CFUKG455KD4A-RO mid-band filters made by Murata Corporation, or any other suitable filters. A cab control unit may be installed in the lead locomotive of the train and communicates with the EOT unit through the LCU. A display unit may be installed in the lead locomotive of the train for displaying information from the EOT unit that is transmitted to the LCU.

JOO 15] The present invention is also directed to a method for converting an EOT radio and/or an LCU radio into a radio capable of receiving both wide band and narrow band signals. The method includes the steps of: providing an EOT radio and/or an LCU radio having a wide band filter in a radio receiver section; removing the wide band filter; and replacing the wide band filter with a new filter that provides reception of both wide band and narrow band transmissions.

[0016] The wide band filter may be configured to provide a usable bandwidth that allows wide band reception for transmissions having a modulation level of about 3.0 kHz. The new filter may be configured to provide a usable bandwidth that allows for transmissions having a modulation level of both 2.5 kHz and 3.0 kHz. The modulation level determines the bandwidth of a transmission. The receiver section with the new filter is thereby configured to receive transmissions with minimal signal distortion and degradation in either a narrow band or a wide band environment.

[0017] The new filter may be a CFUKG455KD4A-RO mid-band filter. The EOT radio may be configured to be attached to a last car of a train. The LCU radio may be configured to be installed in a lead locomotive of a train. The LCU is operably coupled to a cab control unit.

[0018] These and other features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a side schematic view of a train incorporating an LCU and an EOT unit having radios in accordance with the present invention; [0020J FΪG. 2 is a flow diagram of the steps for transitioning a wide band railroad telemetry radio to a railroad telemetry radio that can receive both wide band and narrow band transmissions in accordance with the present invention; and

[002T] FIGS. 3A and 3B are a circuit diagram of a radio receiver section of a railroad telemetry radio configured to receive both wide band and narrow band transmissions in accordance with the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0022] For purposes of the description hereinafter , the terms "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal", and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations, except where expressly specified to the contrary. It is also to be understood that the specific devices illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention.

[0023] With reference to FIG. 1, an mtra-train communications system, denoted generally as reference numeral 1, includes, at a leading end thereof, a locomotive 3 equipped with a locomotive control unit (LCU) 5, an integrated cab control unit 7, a display 9, and an antenna 11. Integrated cab control unit 7 may include a computer which integrates all of the electrical systems in the locomotive. While LCU 5 is shown as mounted on the lead locomotive, an optional configuration would place this unit on one or more trailing locomotive(s), if the train is so arranged.

[0024] Intra-train communication system 1 also includes an end-of-train (EOT) unit 13 that includes a radio having an antenna 15 attached to the last car 17 of the train. In operation, cab control unit 7 communicates with EOT unit 13 through LCU 5 to perform a variety of command and control operations. LCU 5 and EOT unit 13 each include radios and are configured to communicate bi-directionally along a wireless communications link using these radios. The radios of LCU 5 and EOT unit 13 may be the Wabtec synthesized EOT and LCU radios, such as the WPN 15266P, WPN 156223P, or any other suitable communications radio.

[0025] The Federal Communications Commission (FCC) allocates blocks of radio frequencies for railroad communications between EOT unit 13 and LCU 5. The Association of American Railroads (AAR) then further allocates the frequencies on a channel basis, which are used by intra-train communications system 1. Radio-based inlra-train Communications must conform to these AAR channel standards.

[0026] The current AAR standard assigns frequencies on a 25 kHz (wide band) channel basis within the UHF band. However, federal regulations require that by January 1, 2013, radios of EOT unit 13 and LCU 5 communicate in channels separated by only 12.5 kHz (narrow band) in frequency in order to allow for more communications channels. Accordingly, the present invention provides radios for EOT unit 13 and LCU 5 that are able to transmit and receive with minimal signal-to-noise degradation when a narrow band transceiver communicates with a wide band transceiver and vice versa. Accordingly, the present invention allows the railroad companies to gradually introduce narrow band capable radio devices into the market that are capable of interoperating well with existing devices. [0027] With reference to FIGS. 2, 3A, and 3B, and with continuing reference to FIG. 1, a method for transitioning from wide band to narrow band radios is provided. The method includes the following steps. At block 100, an EOT radio and/or an LCU radio are provided that have a radio receiver section 19. Radio receiver section 19 determines receiver bandwidth. Radio receiver section 19 includes a pair of IF filters 21 and 23 that provide a usable bandwidth that allows wide band reception for transmissions having a modulation level of about 3.0 kHz. The modulation level determines the bandwidth of a transmission. Wide band radios usually have a modulation level of between about 3.0 IcHz and about 5.0 kHz. On the other hand, narrow band radios have a modulation level of between about 1.5 kHz to about 2.5 kHz. Accordingly, degradation of a signal occurs when a wide band radio communicates with a narrow band radio.

[0028] In order to improve this degradation of the signal, the following steps are performed. At block 200, filters 21 and 23 are removed from radio receiver section 19. Thereafter, at block 300, filters 21 and 23 are replaced with new filters that provide a usable bandwidth that allows reception for transmissions having a modulation level of either 2.5 kHz or 3.0 kHz.

[0029] Current Wabtec manufactured radios, such as the WPN 15622P and the WPN 156223P, can suitably transmit a minimum shift-keying (MSK) modulated signal at 2.5 kHz and pass the FCC requirements for narrow band operation. The circuit illustrated in FIGS. 3 A and 3B shows that radio receiver section 19 includes two IF filters 21 and 23 operating at 455 kHz. The received signal (not shown) is converted to 455 kHz by an IF mixer 25 and is amplified and then filtered by filters 21 and 23. Filters 21 and 23 determine the ultimate bandwidth of radio receiver section 19. The bandwidth of filters 21 and 23 can be determined by calculating the estimated bandwidth of the signal that is received.

[0030] For instance, Carson's Rule can be used to determine the bandwidth of a frequency modulated signal using the following equation:

B = 2(Afpk + fmax) kHz (Equation 1 )

[0031] Using Carson's Rule, a signal modulated with MSK using a deviation of 3.0 kHz has a bandwidth of approximately 9.6 kHz; and a signal modulated with MSK using a deviation of 2.5 kHz has a bandwidth of approximately 8.6 kHz. Thus, a mid-band filter whose 6 dB bandwidth is 10 kHz is chosen as a suitable new filter for replacing filters 21 and 23. The new filters may be a Murata CFUKG455KD4 A-RO₅ or any other equivalent filter. [0032] Radio receiver section 19 with these new filters is thereby configured to receive transmissions with minimal signal distortion and degradation in either a narrow band or a wide band environment. More specifically, EOT and LCU radios utilizing radio receiver section 19 can operate in cross mode operations, i.e., wide band (3.0 kHz deviation) and narrow band radios operating together, with a mean loss of about 0.63 dB and a 12 dB signal-to-noise and distortion ratio (SINAD) at -116 dBm signal level. Each of these measurements is within acceptable limits.

[0033] Finally, at block 400, the EOT or LCU radio having the modified radio receiver section is coupled to either EOT unit 13 or LCU 5, respectively. EOT unit 13 or LCU 5 is then attached to the train as shown in FIG. 1. The EOT or LCU radio having the modified radio receiver section is thereby capable of receiving either wide band or narrow band signals with minimal signal-to-noise degradation.

[0034] Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements. Furthermore, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.

Claims

THE INVENTION CLAIMED IS

1. A method for transitioning from wide band Io narrow band End of Train (EOT) and/or Locomotive Control Unit (LCU) radios, the method comprising: providing an EOT radio and/or an LCU radio having at least one filter in a radio receiver section that determines receiver bandwidth, the at least one filter providing a usable bandwidth that allows wide band reception for transmissions having a modulation level of about 3.0 kHz; removing the at least one filter; and replacing the at least one filter with at least one new filter that provides a usable bandwidth that allows reception for transmissions having a modulation level of either 2.5 kHz or 3.0 kHz, wherein the receiver section with the at least one new filter is thereby configured to receive transmissions with minimal signal distortion and degradation in either a narrow band or a wide band environment.

2. The method of claim I₅ wherein the modulation level determines the bandwidth of a transmission.

3. The method of claim 1, wherein the at least one new filter is a CFUKG455KD4A-RO mid-band filter.

4. The method of claim 1, wherein the EOT radio is configured to be attached to a last car of a train.

5. The method of claim 1, wherein the LCU radio is configured to be installed in a lead locomotive of a train.

6. A radio telemetry system for use with a locomotive control system of a train comprising: an EOT unit attached to a last car of the train, the EOT unit comprising an EOT radio having a radio receiver section with a filter that provides a usable bandwidth that allows reception for transmissions having a modulation level of either 2.5 kHz or 3.0 kHz; and an LCU installed in a lead locomotive of the train, the LCU comprising an LCU radio having a radio receiver section with a filter that provides a usable bandwidth that allows reception for transmissions having a modulation level of either 2.5 kHz or 3.0 kHz, wherein the EOT radio and the LCU radio are thereby configured to receive transmissions with minimal signal distortion and degradation in either a narrow band or a wide band environment.

7. The radio telemetry system of claim 6, wherein the modulation level determines the bandwidth of a transmission.

8. The radio telemetry system of claim 6, wherein the filters of the EOT radio and the LCU radio are CFUKG455KD4A-RO mid-band filters.

9. The radio telemetry system of claim 6, wherein a cab control unit installed in the lead locomotive of the train communicates with the EOT unit through the LCU.

10. The radio telemetry system of claim 6 further comprising a display unit installed in the lead locomotive of the train for displaying information from the EOT unit that is transmitted to the LCU.

11. A method for converting an EOT radio and/or an LCU radio into a radio capable of receiving both wide band and narrow band signals, the method comprising: providing an EOT radio and/or an LCU radio having a wide band filter in a radio receiver section; removing the wide band filter; and replacing the wide band filter with a new filter that provides reception of both wide band and narrow band transmissions.

12. The method of claim 11 , wherein the wide band filter provides a usable bandwidth that allows wide band reception for transmissions having a modulation level of about 3.0 kHz.

13. The method of claim 12, wherein the modulation level determines the bandwidth of a transmission.

14. The method of claim 11, wherein the new filter provides a usable bandwidth that allows for transmissions having a modulation level of both 2.5 kHz and 3.0 kHz.

15. The method of claim 14, wherein the modulation level determines the bandwidth of a transmission.

16. The method of claim 11, wherein the new filter is a CFUKG455KD4A-RO mid-band filter.

17. The method of claim 11, wherein the EOT radio is configured to be attached to a last car of a train.

18. The method of claim 11, wherein the LCU radio is configured to be installed in a lead locomotive of a train.

19. The method of claim 11 , wherein the LCU is operably coupled to a cab control unit,

20. The method of claim 1 I₅ wherein the receiver section with the new filter is thereby configured to receive transmissions with minimal signal distortion and degradation in either a narrow band or a wide band environment.