AU2012201972B2

AU2012201972B2 - Methods and system of automating track circuit calibration

Info

Publication number: AU2012201972B2
Application number: AU2012201972A
Authority: AU
Inventors: Jeffrey Michael Fries; Richard Lee Lawson; Tom Otsubo
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2008-01-08
Filing date: 2012-04-04
Publication date: 2015-03-26
Anticipated expiration: 2029-01-06
Also published as: AU2012201972A1

Abstract

This application relates to a method for calibrating a track circuit as provided. The track circuit includes a transmit processing unit, a receive processing unit, a plurality 5 of rails coupled in series to form a track section having a first end and a second end. The transmit processing unit is coupled to the track section adjacent the first end. The receive processing unit is coupled to the track section adjacent the second end. The method includes operating the transmit processing u nit so that a first voltage is applied to the track section, operating the receive processing unit to detect a first current 10 signal, and if a parameter of the first current signal is not within a predetermined range, then communicating with the transmit processing unit so that the transmit processing unit automatically applied a second voltage to the tract section, the second voltage having a different magnitude than the first voltage. 938703>

Description

AUSTRALIA Patents Act COMPLETE SPECIFICATION (ORIGINAL) Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: General Electric Company Actual Inventor(s): Richard Lee Lawson, Jeffrey Michael Fries, Tom Otsubo Address for Service and Correspondence: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: METHODS AND SYSTEM OF AUTOMATING TRACK CIRCUIT CALIBRATION Our Ref: 938703 POF Code: 88428/141848 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1- -1a METHODS AND SYSTEM OF AUTOMATING TRACK CIRCUIT CALIBRATION The present application is a divisional application from Australian Patent Application No. 2009204324, the entire disclosure of which is incorporated herein by reference. 5 BACKGROUND OF THE INVENTION This invention relates generally to railroad systems, and more specifically, to methods and system of automatically calibrating track circuits. 10 A rail track circuit typically is used to detect whether a train is present on a track section. Such circuit also can be used to detect broken rails within the track section and/or can be used to transmit signal aspect information through the rails. A typical track circuit includes rails in electrical series with a signal transmitter and a signal receiver. The signal transmitter applies a voltage, sometimes referred to as a transmit voltage, to the rails. As a result, a current signal, 15 sometimes referred to as a receive current, is transmitted through the rails. The receive current is detected by the receiver. When a train composed of one or multiple railcars is located on the track section of the track circuit, the wheels of the railcars act as a shunt between the rails and form a shunt path. The 20 shunt path creates an electrical short between the rails at the location of the train, and such short path effectively prevents the receive current from being received/detected by the signal receiver. Over time, environmental conditions and rail conditions can change. These changing 25 conditions impact ballast resistance of the track circuit. Generally, leakage paths occur through the ballast, and the leakage resistance of such paths varies due to the changing conditions. The varying leakage resistance impacts the receive current. The track circuit therefore is configured, or calibrated, to operate over a range of ballast resistance. 30 Due to the changing conditions, over time, the track circuit may require re-calibration. Known calibration techniques involve positioning human "maintainers" with two-way radios at the transmitter and receiver. The maintainer at the transmitter communicates data related to the applied voltage to the maintainer at the receiver. The receiver maintainer then informs the transmitter maintainer of the current signal received at the receiver. Adjustments are made to 938703> 2 both the transmitter and receiver so that the track circuit operates as desired over the ballast resistance range. Another known calibration technique is for a single human maintainer to perform track circuit calibration by traveling between transmitter and receiver sites (i.e., locations) to make each adjustment. As such, the process of manually calibrating the track 5 circuit settings may be costly, inefficient and/or time-consuming. A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims. 10 BRIEF DESCRIPTION OF THE INVENTION In one aspect, there is a method for calibrating a track circuit, the track circuit including a transmit processing unit, a receive processing unit, and a plurality of rails coupled in series to form a track section having a first end and a second end, the transmit processing unit coupled to the track section adjacent the first end, the receive processing unit coupled to the track 15 section adjacent the second end, said method comprising: applying a first voltage to the track section by the transmit processing unit; and receiving by the receive processing unit a first current related to the first voltage and a leakage resistance between the first end and the second end, and if a parameter of the First current is not within a predetermined range, then transmitting from the receive processing unit a communication to the transmit processing unit 20 so that the transmit processing unit applies a second voltage to the track section, the second voltage having a different magnitude than the first voltage; if the second voltage is applied, receiving by the receive processing unit a second current corresponding to the second voltage, and adjusting the predetermined range based on the leakage resistance for maintaining operation of the track circuit over a range of leakage resistance. 25 In a further aspect, there is provided a track circuit comprising: a remote system; a transmit processing unit and a receive processing unit, said remote system configured for communication with at least one of said transmit processing unit and said receive processing unit; and a plurality of rails coupled in series to form a track section having a first end and a second end, said transmit processing unit coupled to said track section adjacent said first end, 30 said receive processing unit coupled to said track section adjacent said second end; said transmit processing unit configured to apply a first voltage to said track section during operation for track circuit calibration, said receive processing unit configured to detect a first 938703- 3 current related to the first voltage and a leakage resistance between the first end and the second end during operation, if a parameter of said first current is not within a predetermined range, then said receive processing unit is configured to communicate with said transmit processing unit such that said transmit processing unit applies a second voltage to said track 5 section wherein said second voltage has a different magnitude than said first voltage, said predetermined range being adjusted to correspond to a second current, said second current related to said second voltage. In yet another aspect, there is provided a track circuit comprising: a transmit processing unit; a receive processing unit; and a plurality of rails coupled in series to form a track section having 10 a first end and a second end, said transmit processing unit coupled to said track section adjacent said first end, said receive processing unit coupled to said track section adjacent said second end; said transmit processing unit configured to apply a first voltage to said track section during operation, said receive processing unit configured to detect a first current related to the first voltage and a leakage resistance between the first end and the second end 15 during operation, if a parameter of said first current is not within a predetermined range, then said receive processing unit is configured to communicate with said transmit processing unit such that said transmit processing unit applies a second voltage to said track section wherein said second voltage has a different magnitude than said first voltage, said predetermined range being adjusted to correspond to a second current, said second current associated with said 20 second voltage. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of a track circuit, according to an embodiment of the present invention. Figure 2 is a flowchart depicting a method of calibrating the track circuit shown in Figure 1, 25 according to an embodiment of the present invention. Figure 3 is a flowchart depicting a method of calibrating the track circuit 100 shown in Figure I from a remote location, according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION 30 Figure 1 is a schematic illustration of at least one track circuit 100 in accordance with an exemplary embodiment of the present invention. Track circuit 100 enables automatic evaluation and calibration of a section of the railroad track. Track circuit 938703> -4 100 includes a plurality of rails 12 and 14 coupled in series to form a track section 101 having a first end 16 and a second end 18. Track section 101 may include a plurality of ties (not shown) coupling rails 12 and 14 together. The ties are laid in the ground and substantially covered with ballast (e.g., small stones) to hold the ties in place. Over time, environmental conditions and rail conditions can change. The changing conditions impact ballast resistance of track circuit 100. Generally, leakage paths occur through the ballast, and the leakage resistance impacts the current levels. Track circuit 100 therefore is configured, or calibrated, to operate over a range of ballast resistance, as will be discussed in more detail below. Track circuit 100 further includes a transmit processing unit 103 and a receive processing unit 105. In the exemplary embodiment, adjustments are made to both units 103 and 105 so that track circuit 100 operates as desired over a given ballast resistance range. In the exemplary embodiment, transmit processing unit 103 is coupled to adjacent track section first end 16, and receive processing unit 105 is coupled to adjacent track section second end 18. Transmit processing unit 103 is configured to apply a first voltage across track section 101 during operation. For example, transmit processing unit 103 may be configured to apply a voltage across track section 101 at end 16, thereby generating a current in a direction shown in Figure 1 (that is, assuming a positive voltage relative to the second end 18, the current signal is from left to right in Figure 1). Receive processing unit 105 is configured detect a first current through, for example, track section 101 at end 18. In an alternative embodiment, unit 103 has similar components and similar functionality to unit 105, and unit 105 has similar components and similar functionality to unit 103. In the exemplary embodiment, transmit processing unit 103 includes at least one energy source 110 and at least one receiver 116, and receive processing unit 105 includes at least one energy source 112 and at least one receiver 114. Moreover, in the exemplary embodiment, each unit 103 and unit 105 includes at least one program and at least one arithmetic logic unit. In an alternative embodiment, each unit 103 and unit 105 does not include at least one arithmetic logic unit. Generally, each unit 103 and 105 of a coded track circuit includes arithmetic logic units, and each unit 103 and 105 of a non-coded track circuit does not include arithmetic logic units. For -5 example, non-coded track circuit units have only an on or off current detection. With an on or off current detections, the on or off transmit voltage needs to be high enough to allow current detection. In the exemplary embodiment, computer programs, or software, are stored in memory device 206 within unit 103 and/or unit 105. A suitable memory device 206 in one embodiment is an electrically erasable programmable read only member (EEPROM). Moreover, it is understood that other types of memory could be utilized, such as simple read only memory (ROM), or programmable read only member (PROM), or, if the ability to reprogram the ROM is desirable, erasable programmable read only memory (EPROM), which are conventionally erased by exposure to ultraviolet light, or FLASH memory. Track circuit 100 may be calibrated, operated, and monitored from a remote location. For example, in one embodiment, transmit and receive processing units 103 and 105 are configured to communicate with a remote system 40 via a wireless network 42. The remote system 40 may be, for example, a dispatch center, a rail vehicle, a device carried by an operator or track maintenance personnel, or the like. In the exemplary embodiment, communication between the remote system 40 and units 103 and 105 is based on a client-server relationship (over the wireless network 42 or otherwise) using established protocols such as, but not limited to, the Internet Protocol (IP). In an alternative embodiment, communication between the remote system 40 and units 103 and 105 may include any suitable means that enables track circuit 100 to function as described herein. Figure 2 is a flowchart 198 depicting a method of calibrating at least a portion of track circuit 100. In the exemplary embodiment, each unit 103 and 105 is selectively operable between a calibration mode and an operational mode. In the exemplary embodiment, a railroad operator (i.e., a human "maintainer") selects local calibration mode 199 to begin 201 calibration of track section 101. In the exemplary embodiment, unit 103 is configured to apply 202 a voltage 203 across track section 101, and unit 105 is configured to detect 205 a current signal 204 -6 flowing through track section 101. In an alternative embodiment, the track section 101 is calibrated in a substantially similar matter to the method described herein; however, unit 105 is configured to apply 202 voltage 203 across track section 101, and unit 103 is configured to detect a current signal 204 flowing through track section 101. Moreover, in the exemplary embodiment, at least one unit 103 and/or unit 105 includes memory device 206 for at least temporarily storing various voltage and current parameters and a predetermined current threshold range. For example, the transmit voltage may be approximately 2 volts while the receive current parameter may be approximately 1.5 amps and the threshold range may be set at approximately 0.5 amps. The predetermined current threshold range 223 may be input as a suggested threshold by the maintainer. In the exemplary embodiment, the predetermined current threshold range 223 is approximately 0.5-6.0 amps. In an alternative embodiment, the predetermined current threshold range 223 is pre programmed within unit 105. In the exemplary embodiment, unit 105 is configured to adjust 208 the range 223 based upon the changing ballast condition. For example, if the track circuit is set up by the maintainer when the ballast leakage is low (i.e., good conduction down the rail), then the transmit voltage may be set to approximately 1 volt and the receive current may be approximately 2 amps. For example, if a train is detected in the track circuit, the train shorts the rails in the track circuit causing a small amount of current to be received at unit 105 (i.e. receiver). As such, the threshold could be set to approximately 0.6 amps such that if the receive current is below 0.6 amps, the track circuit will declare that a train is on the track circuit. However, if the ballast leakage increases (i.e., low conduction down the rail), then the receive current will be less due to the ballast leakage. Therefore, if the receive current drops below 0.6 amps at unit 105 (i.e., receiver), a train is "detected" on the track circuit due to the ballast conditions even though no train actually occupies the track. As such, range 223 is adjusted based upon the changing ballast conditions.

-7 Once current threshold range 223 has been adjusted based upon the ballast conditions, unit 105 is configured to apply 212 the magnitude of range 223 and the parameters of signal 204 across track section 101, and unit 103 is configured to detect 214 the magnitude of range 223 and signal 204 flowing through track section 101. In the exemplary embodiment, at least one of unit 103 and/or unit 105 also includes a logic module 220 including a function block 222. Function block 222 within unit 103 is configured to compare 216 at least one parameter of a detected current signal to the current threshold range 223. After comparison of a parameter of current signal 204 to current threshold range 223, if a parameter of current signal 204 is not within the range, then unit 103 is configured to automatically adjust 225 voltage 203 and unit 103 is configured to apply a second voltage across track section 101. In the exemplary embodiment, the second voltage has a different magnitude than the first voltage 203, and the method, described herein, repeats until a predetermined parameter of current signal 204 is within the range 223. On the other hand, after comparison of a parameter of current signal 204 to current threshold range 223, if current signal 204 is within the range 223, then unit 105 is configured to communicate with unit 103 such that unit 103 maintains the magnitude of first voltage signal 203. Moreover, in the exemplary embodiment, if current signal 204 is within range 223, then unit 105 is configured to communicate with unit 103 such that unit 103 records first voltage signal 203 parameters, first current signal 204 parameters, and current threshold range 223 parameters. In the exemplary embodiment, a timing mechanism (not shown) is coupled to each unit 103 and 105. (The timing mechanism may be part of software/computer code as executed by a processor in the unit 103, 105.) The timing mechanism is configured to switch each respective unit 103 and 105 to the operational mode after a predetermined time to prevent units 103 and 105 from remaining in calibration mode 199. For example, unit 103 and/or 105 would switch from calibration mode 199 to the operational mode after approximately 1 minute of inactivity in calibration mode 199. The default for switching out of calibration mode 199 may be to a safe default value -8 or to the pre-determined values. In an alternative embodiment, once track section 101 has been calibrated, then the maintainer may return each unit 103 and/or 105 to the operational mode. Moreover, at least one unit 103 and/or 105 may be coupled to an output display (not shown) such that various stored parameters may be output to the display. During operation, in the exemplary embodiment, the maintainer sets transmit processing unit 103 to local calibration mode 199 to begin 201 automatic calibration of track section 101. In calibration mode 199, unit 103 applies 202 a first voltage signal 203 (e.g., test pulses) across track section 101. In an alternative embodiment, signal 203 is transmitted from unit 103 as a predefined pulse pattern, a message, and/or any other communication media that enables track circuit 100 to function as described herein. In the exemplary embodiment, the unit 105 detects 205 the first current signal 204. In the exemplary embodiment, unit 105 at least temporarily stores the parameters of signal 203 and range 223 in memory device 206. In the exemplary embodiment, unit 105 may adjust 208 the range 223 based upon changing ballast conditions. In the exemplary embodiment, unit 105 adjusts 208 the range 223 based upon the changing ballast condition. For example, if the track circuit is set up by the maintainer when the ballast leakage is low (i.e., good conduction down the rail), then the transmit voltage may be set to approximately I volt and the receive current may be approximately 2 amps. For example, if a train is detected in the track circuit, the train shorts the rails in the track circuit causing a small amount of current to be received at unit 105 (i.e., receiver). As such, the threshold could be set to approximately 0.6 amps such that if the receive current is below 0.6 amps, the track circuit will declare that a train is on the track circuit. However, if the ballast leakage increases (i.e., low conduction down the rail), then the receive current will be less due to the ballast leakage. Therefore, if the receive current drops below 0.6 amps at unit 105 (i.e., receiver), a train is "detected" on the track circuit due to the ballast conditions even though no train actually occupies the track. As such, range 223 is adjusted based upon the changing ballast conditions.

-9 Once current threshold range 223 has been adjusted based upon the ballast conditions, unit 105 applies 212 the magnitude of range 223 and the parameters of signal 204 across track section 101, and unit 103 detects 214 the magnitude of range 223 and signal 204 flowing through track section 101. Function block 222 within unit 103 then compares 216 at least one parameter of signal 204 to the current threshold range 223. In the exemplary embodiment, after comparison of a parameter of current signal 204 to current threshold range 223, if a parameter of first current signal 204 is not within the current threshold range 223, then unit 103 automatically adjusts 225 first voltage 203 to a second voltage. Specifically, in the exemplary embodiment, second voltage has a different magnitude than first voltage signal 203. Unit 103 then applies 202 the second voltage across track section 101. As such, unit 105 detects a second current signal, and the method repeats until a predetermined parameter of the current signal is within the range. (The second current signal relates to the second voltage, in that the second current signal is a function of the second voltage and the electrical characteristics, e.g., impedance, of the track section 101.) On the other hand, if after comparison of a parameter of current signal 204 to current threshold range 223, the parameter current signal 204 is within the range, then unit 103 maintains the magnitude of first voltage signal 203. Moreover, in the exemplary embodiment, if current signal 204 is within range 223, then unit 103 records 218 first voltage signal 203 parameters, first current signal 204 parameters, and current threshold range 22.3 parameters. Calibration of track section 101 is complete 219 when the various parameters have been recorded by unit 103. In the exemplary embodiment, when calibration of track section 101 is complete, the timing mechanism (not shown) switches each respective unit 103 and 105 to the operational mode after a predetermined time to prevent units 103 and 105 from remaining in calibration mode 199. For example, unit 103 and/or 105 would switch from calibration mode 199 to the operational mode after approximatelyl minute of inactivity in calibration mode 199. The default for switching out of calibration mode 199 may be to a safe default value or to the pre-determined values. In an alternative -10 embodiment, once track section 101 has been calibrated, then the maintainer may return each unit 103 and/or 105 to the operational mode. Moreover, at least one unit 103 and/or 105 may be coupled to an output display (not shown) such that various stored parameters may be output to the display. Figure 3 is a flowchart 300 depicting a method of calibrating at least a portion of track circuit 100 from a remote location. In the exemplary embodiment, each unit 103 and 105 is selectively operable between a calibration mode 301 and an operational mode. In the exemplary embodiment, track circuit 100 may be calibrated, operated, and monitored from a remote location using a remote system 40 configured to apply a signal to at least one of unit 103 and/or unit 105. For example, transmit and receive processing units 103 and 105 are configured to communicate with the remote system 40 via a wireless network 42. In an alternative embodiment, a railroad operator (i.e., a human "maintainer") selects remote calibration mode 301 to begin calibration of track section 101. In the exemplary embodiment, the remote system 40 is configured to apply (e.g., transmit) 299 an initiation signal to unit 103 instructing unit 103 to operate in calibration mode 301, and unit 103 is configured to detect 302 the initiation signal from the remote system. In the exemplary embodiment, unit 103 is configured to apply 307 a start-up signal 304 across track section 101. Unit 105 is configured to detect signal 304 and is configured to begin 309 automatic calibration of track section 101. As such, unit 105 is configured to apply 313 a voltage signal 305 across track section 101, and unit 103 is configured to detect 312 a current signal 306 flowing through track section 101. In an alternative embodiment, the remote system is configured to apply a signal to track section 101 instructing unit 105 to operate in calibration mode 301. As such, the track section 101 is calibrated in a substantially similar matter to the method described herein. In the exemplary embodiment, at least one of unit 103 and/or unit 105 includes a memory device 206 for at least temporarily storing various parameters and a current threshold range. The current threshold range 303 may be input into unit 103 as a suggested threshold by the maintainer. In an alternative embodiment, the current -11 threshold range 303 is pre-programmed within unit 103. In the exemplary embodiment, unit 103 is configured to adjust the range 303 based upon changing ballast conditions. For example, if the track circuit is set up by the maintainer when the ballast leakage is low (i.e., good conduction down the rail), then the transmit voltage may be set to approximately I volt and the receive current may be approximately 2 amps. For example, if a train is detected in the track circuit, the train shorts the rails in the track circuit causing a small amount of current to be received at the receiver unit. As such, the threshold could be set to approximately 0.6 amps such that if the receive current is below 0.6 amps, the track circuit will declare that a train is on the track circuit. However, if the ballast leakage increases (i.e., low conduction down the rail), then the receive current will be less due to the ballast leakage. Therefore, if the receive current drops below 0.6 amps at the receiver unit, a train is "detected" on the track circuit due to the ballast conditions even though no train actually occupies the track. As such, range 303 is adjusted based upon the changing ballast conditions. Once current threshold range 303 has been adjusted based upon the ballast conditions, unit 105 is configured to apply 316 the magnitude of range 303 and the parameters of signal 305 across track section 101, and unit 103 is configured to detect 318 the magnitude of range 303 and signal 305 flowing through track section 101. In the exemplary embodiment, at least one of unit 103 and/or unit 105 also includes a logic module 220 including a function block 222. Function block 222 within unit 105 is configured to compare at least one parameter of a detected signal to a threshold range. After comparison of a parameter of current signal 306 to current threshold range 303, if a parameter of current signal 306 is not within the range, then unit 105 is configured to automatically apply a second voltage across track section 101. In the exemplary embodiment, the second voltage has a different magnitude than the first voltage 305, and the method, described herein, repeats until a predetermined parameter of current signal 306 is within the range 303. On the other hand, after comparison of a parameter of current signal 306 to predetermined current threshold range 303, if a parameter of current signal 306 is -12 within the range, then unit 105 maintains the magnitude of first voltage signal 305. Moreover, in the exemplary embodiment, if current signal 306 is within range 303, then unit 105 communicates with unit 103 such that unit 103 records first voltage signal 305 parameters, first current signal 306 parameters, and current threshold range 303 parameters. In the exemplary embodiment, a timing mechanism (not shown) is coupled to at least one unit 103 and/or 105. Once unit 103 records first voltage signal 305 parameters, first current signal 306 parameters, and current threshold range 303 parameters, calibration is substantially complete, and the remote system 40 is configured to apply a signal to the timing mechanism. The signal is configured to switch the timing mechanism from calibration mode 301 to the operational mode to prevent units 103 and 105 from remaining in calibration mode 301. In an alternative embodiment, each timing mechanism is configured to switch from calibration mode 301 to the operational mode after a predetermined time to prevent units 103 and 105 from remaining in calibration mode 301. In a further alternative embodiment, once track section 101 has been calibrated, then the maintainer may return each unit 103 and/or 105 to the operational mode. Moreover, at least one unit 103 and/or 105 may be coupled to an output display (not shown) such that various stored parameters may be output to the display. During operation, in the exemplary embodiment, the remote system applies (e.g., transmits) 299 an initiation signal to unit 103 instructing unit 103 to operate in calibration mode 301, and unit 103 detects 302 the initiation signal. In the exemplary embodiment, unit 103 communicates with unit 105 such that unit 105 applies 307 a start-up signal across track section 101 to begin calibration of track section 101. In the exemplary embodiment, in calibration mode 301, unit 103 applies 307 a start-up signal 304 to unit 105. Start-up signal 304 instructs unit 105 to begin calibration or re-calibration of track section 101, and unit 105 begins 309 calibration or re calibration. In the exemplary embodiment, unit 105 applies 313 first voltage signal 305 across track section 101. In an alternative embodiment, signal 305 is applied across track section 101 as a predefined pulse pattern, a message, and/or any other communication media that enables track circuit 100 to function as described herein.

-13 In the exemplary embodiment, unit 103 detects 312 a first current signal 306. In the exemplary embodiment, unit 103 at least temporarily stores the parameters of current signal 306 in memory device 206. In the exemplary embodiment, unit 103 automatically adjusts 314 the range 303 based upon the changes in the condition of the ballast described herein above. When a train enters a track circuit, the received current drops suddenly and is, therefore, distinguishable from ballast deterioration which causes the receive current to drop much more slowly. For example, if the track circuit is set up by the maintainer when the ballast leakage is low (i.e., good conduction down the rail), then the transmit voltage may be set to approximately I volt and the receive current may be approximately 2 amps. For example, if a train is detected in the track circuit, the train shorts the rails in the track circuit causing a small amount of current to be received at the receiver unit. As such, the threshold could be set to approximately 0.6 amps such that if the receive current is below 0.6 amps, the track circuit will declare that a train is on the track circuit. However, if the ballast leakage increases (i.e., low conduction down the rail), then the receive current will be less due to the ballast leakage. Therefore, if the receive current drops below 0.6 amps at the receiver unit, a train is "detected" on the track circuit due to the ballast conditions even though no train actually occupies the track. As such, range 303 is adjusted based upon the changing ballast conditions. Once range 303 has been adjusted, unit 105 applies 316 the magnitude of the parameters signal 305 across track section 101 such that unit 103 detects 318 the magnitude of the parameters of signal 305. Function block 222 within unit 105 compares 320 at least one parameter of current signal 306 to the current threshold range 303. In the exemplary embodiment, after comparison of a parameter of current signal 306 to predetermined current threshold range 303, if the parameter of current signal 306 is not within the predetermined current threshold range 303, then unit 105 automatically adjusts 321 voltage 305 and applies 313 a second voltage across track section 101. Specifically, in the exemplary embodiment, second voltage has a different magnitude than first voltage 305. As -14 such, unit 103 detects a second current signal, and the method repeats until a predetermined parameter of current signal 306 is within the range 303. On the other hand, if after comparison of a parameter of the first current signal 306 to a predetermined current threshold range 303, the parameter of the first current signal 306 is within the range, then unit 105 maintains the magnitude of first voltage signal 305. Moreover, in the exemplary embodiment, if current signal 306 is within range 303, then unit 105 communicates with unit 103 such that unit 103 records 322 first voltage signal 305 parameters, first current signal 306 parameters, and current threshold range 303 parameters within memory device 206. Calibration of track section 101 is complete 324 when the various parameters have been recorded by unit 103. In the exemplary embodiment, once track section 101 is complete, the remote system 40 communicates with at least one of the timing mechanisms (not shown) coupled to unit 103 and/or unit 105 such that the remote system instructs the timing mechanism to switch each respective unit 103 and/or 105 to the operational mode from calibration mode 301 to prevent units 103 and/or 105 from remaining in calibration mode 301. In an alternative embodiment, each timing mechanism switches from calibration mode 301 to the operational mode after a predetermined time to prevent units 103 and 105 from remaining in calibration mode 301. In a further alternative embodiment, once track section 101 has been calibrated, then the maintainer may return each unit 103 and/or 105 to the operational mode. Moreover, at least one unit 103 and/or 105 is coupled to an output display (not shown) such that various stored parameters are output to the display. The above-described methods and systems enable automatic calibration of the transmitting voltage and the receiving current thresholds for a track circuit of a railroad. Track circuit calibration may be required when the environment changes and/or when the railroad conditions change. Accordingly, the need for manual setup and calibration is eliminated, thereby facilitating a reduction in the chance for error, in costs and/or time associated with maintenance of the railroad. Moreover, the above described methods and system increase the safety of the railroad.

-15 At least one unit 103 and/or 105 may include, but is not limited to including, a microprocessor, microcontroller, a microcomputer, a programmable logic controller, an application specific integrated circuit, or any other programmable circuit. Therefore, the term "processor," as used herein, is not limited to just those integrated circuits referred to in the art as computers, but broadly refers to microprocessors, microcontrollers, microcomputers, programmable logic controllers, application specific integrated circuits, and other programmable circuits, and these terms are used interchangeably herein. The arithmetic logic units, memory units/devices, logic modules, etc. may be separate units, or they may be part of a processor or otherwise interfaced for functioning with a processor. For example, certain processors include a "built in" arithmetic logic unit. The term "automatic" or "automatically" as used herein refers to machine operation (or the steps of a method otherwise being performed) without the requirement of human intervention or interaction. Additionally, in certain embodiments herein the track circuit is characterized as being coupled in electronic data communication to a remote system. This means that the track circuit is in communication with the remote system for the exchange of electronic data there between. Although embodiments of the present invention are characterized as relating to voltage and current signal magnitude, e.g., recording voltage and current signal magnitude, other voltage/current signal characteristics may be recorded or otherwise instead of magnitude without departing from the spirit and scope of the invention. Additionally, the terms "voltage" and "voltage signal," and "current" and "current signal," are used interchangeably herein unless otherwise specified, respectively. As will be appreciated by one skilled in the art and based on the foregoing specification, the above-described embodiments of the invention may be implemented using computer programming or engineering techniques including computer software, firmware, hardware or any combination or subset thereof, wherein the technical effect is to calibrate a track circuit. Any such resulting program, having computer-readable code means, may be embodied or provided within one or more computer-readable media, thereby making a computer program product, i.e., an article of manufacture, -16 according to the discussed embodiments of the invention. The computer readable media may be, for example, but is not limited to, a fixed (hard) drive, diskette, optical disk, magnetic tape, semiconductor memory such as read-only memory (ROM), and/or 5 any transmitting/receiving medium such as the Internet or other communication network or link. The article of manufacture containing the computer code may be made and/or used by executing the code directly from one medium, by copying the code from one medium to another medium, or by transmitting the code over a network. 10 As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 15 Exemplary embodiments of a system and method for automatic calibrating a railroad track circuit are described above in detail. The system and method illustrated are not limited to the specific embodiments described herein, but rather, components of the system may be utilized independently and separately from other components described 20 herein. Further, steps described in the method may be utilized independently and separately from other steps described herein. While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with 25 modification within the spirit and scope of the claims. Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the 30 presence of one or more other features, integers, steps or components, or group thereto. 938703>

Claims

1. A method for calibrating a track circuit, the track circuit including a transmit 5 processing unit, a receive processing unit, and a plurality of rails coupled in series to form a track section having a first end and a second end, the transmit processing unit coupled to the track section adjacent the first end, the receive processing unit coupled to the track section adjacent the second end, said method comprising: applying a first voltage to the track section by the transmit processing unit; and 10 receiving by the receive processing unit a first current related to the first voltage and a leakage resistance between the first end and the second end, and if a parameter of the first current is not within a predetermined range, then transmitting from the receive processing unit a communication to the transmit processing unit so that the transmit processing unit applies a second voltage to the track section, the 15 second voltage having a different magnitude than the first voltage; if the second voltage is applied, receiving by the receive processing unit a second current corresponding to the second voltage, and adjusting the predetermined range based on the leakage resistance for maintaining operation of the track circuit over a range of leakage resistance. 20

2. A method in accordance with Claim 1 further comprising operating the receive processing unit to detect the first current, and if the parameter of the first current is within the predetermined range, then communicating with the transmit processing unit so that the transmit processing unit records at least one of a magnitude of the first voltage, a magnitude of the first current, and a magnitude of the second current. 25

3. A method in accordance with Claim 2 further comprising operating at least one of the transmit processing unit and the receive processing unit such that when at least one of the magnitude of the first voltage, the magnitude of the first current, and the magnitude of the second current is recorded, the track circuit calibration is complete. 938703, -18

4. A method in accordance with any one of Claims I to 3 wherein the track circuit is coupled in electronic data communication to a remote system, said method further comprising operating the remote system such that a signal is applied to the transmit processing unit instructing the transmit processing unit to apply a start-up 5 signal to the track section.

5. A method in accordance with any one of Claims I to 3 wherein the track circuit is coupled in electronic data communication to a remote system, said method further comprising operating the remote system such that a signal is applied to the receive processing unit instructing the receive processing unit to apply a start-up signal to the 10 track section.

6. A method in accordance with Claim 5 further comprising operating the transmit processing unit to detect the start-up signal so that the transmit processing unit applies the first voltage to the track section.

7. A track circuit comprising: 15 a remote system; a transmit processing unit and a receive processing unit, said remote system configured for communication with at least one of said transmit processing unit and said receive processing unit; and a plurality of rails coupled in series to form a track section having a first end 20 and a second end, said transmit processing unit coupled to said track section adjacent said first end, said receive processing unit coupled to said track section adjacent said second end; said transmit processing unit configured to apply a first voltage to said track section during operation for track circuit calibration, said receive processing unit 25 configured to detect a first current related to the first voltage and a leakage resistance between the first end and the second end during operation, if a parameter of said first current is not within a predetermined range, then said receive processing unit is configured to communicate with said transmit processing unit such that said transmit 938703> -19 processing unit applies a second voltage to said track section wherein said second voltage has a different magnitude than said first voltage, said predetermined range being adjusted to correspond to a second current, said second current related to said second voltage. 5

8. A track circuit in accordance with Claim 7 wherein said receive processing unit is configured to detect said second-current.

9. A track circuit in accordance with Claim 8 wherein said receive processing unit is configured to detect said first current, and if said parameter of said first current is within said predetermined range, then communicating with said transmit processing 10 unit so that said transmit processing unit records at least one of a magnitude of said first voltage, a magnitude of said first current, and a magnitude of said second current.

10. A track circuit in accordance with Claim 9 wherein said track circuit calibration is complete when at least one of said transmit processing unit and said receive processing unit record at least one of the magnitude of said first voltage, the magnitude 15 of said first current, and the magnitude of said second current.

11. A track circuit in accordance with Claim 9 or 10 wherein said track circuit remote system is configured to apply a signal to said transmit processing unit instructing said transmit processing unit to apply a start-up signal to said track section.

12. A track circuit in accordance with any one of Claims 9 to 11 wherein remote 20 system is configured to apply a signal to said receive processing unit instructing said receive processing unit to apply a start-up signal to said track section.

13. A track circuit in accordance with Claim 12 wherein said transmit processing unit is configured to detect said start-up signal and to apply said first voltage to said track section in response to detecting the start-up signal. 25

14. A track circuit comprising: a transmit processing unit; a receive processing unit; and 938703> -20 a plurality of rails coupled in series to form a track section having a first end and a second end, said transmit processing unit coupled to said track section adjacent said first end, said receive processing unit coupled to said track section adjacent said second end; 5 said transmit processing unit configured to apply a first voltage to said track section during operation, said receive processing unit configured to detect a first current related to the first voltage and a leakage resistance between the first end and the second end during operation, if a parameter of said first current is not within a predetermined range, then said receive processing unit is configured to communicate 10 with said transmit processing unit such that said transmit processing unit applies a second voltage to said track section wherein said second voltage has a different magnitude than said first voltage, said predetermined range being adjusted to correspond to a second current, said second current associated with said second voltage.

15 15. A track circuit in accordance with Claim 14 wherein said receive processing unit is configured to detect said second current.

16. A track circuit in accordance with Claim 15 wherein said receive processing unit is configured to detect said first current, and if said parameter of said first current is within said predetermined range, then communicating with said transmit processing 20 unit so that said transmit processing unit records at least one of a magnitude of said first voltage, a magnitude of said first current, and a magnitude of said second current.

17. A track circuit in accordance with Claim 16 wherein said track circuit calibration is complete when at least one of said transmit processing unit and said receive processing unit record at least one of the magnitude of said first voltage, the 25 magnitude of said first current, and the magnitude of said second current. 938703>