SELF-CALIBRATION OF SIGNAL LEVELING OF ELECTRICAL LINE COMMUNICATION

Abstract

A system for calibrating signals received through a power line within a vehicle includes a signal conditioning circuit that converts analog input signals into digital input signals. In one configuration, the circuit includes an adjustable gain circuit that outputs an amplifier gain signal, establishing an amplifier gain level, and an amplifier that outputs amplified signals in response to the analog input signals and the amplifier gain signal. In another configuration, the circuit includes a bias circuit that outputs a bias signal, establishing a bias level, and a comparator that generates the digital input signals in response to the analog input signals and the bias signal.A controller receives the digital input signals and generates, depending on the mode, one or more control signals configured to control the amplifier gain signal setting and amplifier gain level and / or the bias signal and bias level.

Description

POWER LINE COMMUNICATION SIGNAL LEVELING SELF-CALIBRATION Field of Invention This invention relates to communications systems used in vehicles such as articulated trucks. In particular, the invention relates to a system and method for calibrating signals received over an electrical line within a vehicle. Background of the Invention Power line communication (PLC) is a communication method in which data is transmitted over wires that are also used to supply electrical power. The data is encoded within a signal that is transmitted over the wires at frequency ranges outside those used to transmit electrical power. PLC is advantageous over other communication methods because it allows communication using existing wiring. Articulated trucks frequently employ PLCs to exchange messages between members of the articulated truck, including, for example, sensor readings from vehicle systems such as anti-lock braking systems, collision avoidance systems, tire pressure monitoring systems, and other vehicle systems, as well as commands used to control zonn Ln / eznz / e / YiAi systems. Ref. 349596 for anti-lock braking, lighting systems and other vehicle systems. In a vehicle employing PLCs, a plurality of electronic control units or controllers may transmit signals to, and / or receive signals from, other controllers on the vehicle along the power line. Furthermore, in vehicles such as articulated trucks having multiple members, each member of the vehicle (including the tractors, each trailer, and any dollies) may include one or more controllers that transmit signals to, and / or receive signals from, other controllers along the power line. The distance between any two controllers on the vehicle will vary and may vary significantly in, for example, an articulated truck having multiple trailers. Because signals tend to attenuate over longer distances along the power line, the amplitude of the signals received by one controller from other controllers on the vehicle may vary with the variation in the distance between the controllers.Conventional signal conditioning circuits used to receive signals transmitted along a power line and condition those signals for delivery to a controller are not configured to handle signals with different amplitudes. Instead, conventional signal conditioning circuits amplify each received signal equally and cannot adjust to account for changes in amplitude. As a result, conventional systems may not detect signals transmitted over longer distances and having relatively small amplitudes. Conventional signal conditioning circuits are also configured to apply the same level and type of bias (e.g., linear biasing or autobiasing) when handling received signals. As a result, conventional systems fail to optimize bias by allowing variation in the level or type of bias. The inventors herein have recognized the need for a system and method for calibrating signals received over an electrical line within a vehicle that minimizes and / or eliminates one or more of the deficiencies identified above. Brief Description of the Invention This invention relates to communications systems used in vehicles such as articulated trucks. In particular, the invention relates to a system and method for calibrating signals received over an electrical line within a vehicle. An embodiment of a system for calibrating signals received over a power line within a vehicle includes a signal conditioning circuit configured to convert analog input signals received over the power line in the vehicle into digital input signals. The signal conditioning circuit includes an adjustable gain circuit configured to output an amplifier gain signal that establishes an amplifier gain level, and an amplifier configured to output amplified signals in response to the analog input signals and the amplifier gain signal. Digital input signals are formed in response to the amplified signals.The system further includes a controller configured to receive the input digital signals and to generate control signals configured to control the configuration of the amplifier gain signal output by the adjustable gain circuit and the amplifier gain level. Another embodiment of a system for calibrating signals received over a power line within a vehicle includes a signal conditioning circuit configured to convert analog input signals received over the power line in the vehicle into digital input signals. The signal conditioning circuit includes a bias circuit configured to output a bias signal that establishes a bias level and a comparator configured to generate digital input signals responsive to the analog input signals and the bias signal. The system further includes a controller configured to receive the digital input signals and generate one or more control signals configured to control the configuration of the bias signal output by the bias circuit and the bias level. Another embodiment of a system for calibrating signals received over a power line within a vehicle includes a signal conditioning circuit configured to convert analog input signals received over the power line in the vehicle into digital input signals. The signal conditioning circuit includes an adjustable gain circuit configured to output an amplifier gain signal that establishes an amplifier gain level, and an amplifier configured to output amplified signals responsive to the analog input signals and the amplifier gain signal. The signal conditioning circuit further includes a bias circuit configured to output a bias signal that establishes a bias level, and a comparator configured to generate digital input signals responsive to the amplified signals and the bias signal.The system further includes a controller configured to receive the digital input signals and generate one or more amplifier gain control signals configured to control the configuration of the amplifier gain signal Ln / eznz / B / YiAi output by the adjustable gain circuit and the amplifier gain level. The controller is further configured to generate one or more bias control signals configured to control the configuration of the bias signal output by the bias circuit and the bias level. A system and method for calibrating signals received over a power line within a vehicle in accordance with the present teachings represents an improvement over conventional systems and methods. In particular, embodiments of the system and method described herein allow for adjustment of the amplifier gain in the signal conditioning circuit, thereby ensuring that the associated controller will receive signals generated by other controllers located at varying distances from the controller in the vehicle. Embodiments of the system and method described herein may, alternatively, or in addition, allow for adjustment of the level and type of bias applied to the received signals, allowing the system to optimize signal bias. The above and other aspects, features, details, utilities and advantages of the present invention will become apparent from a reading of the following description and claims, and from a review of the attached figures. Brief Description of the Figures Figure 1 is a schematic view of a vehicle including a plurality of electronic systems communicating along an electrical line in the vehicle. Figure 2 is a schematic and diagrammatic view of a system for calibrating signals received through an electrical line within a vehicle according to one embodiment of the teachings herein. Figures 3A-3E are flow diagrams illustrating steps in a method for calibrating signals received over an electrical line within a vehicle in accordance with one embodiment of the teachings herein. Detailed Description of the Invention Referring now to the figures where like reference numerals are used to identify identical components in the various views, Figure 1 illustrates a vehicle, and in particular, an articulated lorry 10. The articulated lorry 10 (also referred to as a semi-trailer) contains a truck or tractor 12 and one or more trailers 14i...14N. The tractor 12 contains a power unit, such as an internal combustion engine, and steering and drive axles. The tractor 12 also contains a battery 16 for use in starting the power unit and supplying power to various accessory systems. The trailers 14i...14n are provided for storing cargo and are removably coupled to the tractor 12. Although a pair of trailers 14 are shown in the illustrated embodiment, it should be understood that the number of trailers 14 attached to the tractor 12 may vary. The tractor 12 and trailers 14 may include various fluid and electrical lines extending between the tractor 12 and the trailers 14, including the electrical line 18. The fluid and power lines allow for the delivery of fluid and electrical power from the tractor 12 to the trailers 14 for use in, for example, tire pressure management, braking, and activation of taillights on the trailer 14. The electrical line 18 is also part of a network used to transmit communications between various electronic systems 20, 22, and 22 on the tractor 12 and trailers 14, respectively. The systems 20, 22 may comprise any of a wide variety of systems commonly employed on the semitrailer 10 including, for example, anti-lock braking systems, collision avoidance systems, tire pressure monitoring and control systems, trailer load monitoring systems, and lighting systems.The electrical line 18 may allow for transmission of data from one or more systems 22 on trailers 14 to a system 20 on the tractor 12 including, for example, sensor readings indicative of the operation of an anti-lock braking system, the location of vehicles and surrounding infrastructure, pressure within the tires on a trailer 14, or a change in the load being carried by a trailer 14. The electrical line 18 may also allow for transmission of commands and data from the tractor 12 to the trailers 14 for use in controlling elements of an anti-lock braking system, tire pressure monitoring system, or lighting system on one or more trailers 14. Referring now to Figure 2, each system 20, 22 may include a system 24 for calibrating signals received via power line 18. System 24 may include a signal conditioning circuit 26 and a controller 28. Signal conditioning circuit 26 is provided for conditioning signals received from power line 18 for use by controller 28, and in particular for converting analog input signals received via power line 18 into digital input signals for controller 28. The signals may be transmitted along power line 18 at a frequency between 100-400 KHz using amplitude shift keying (ASK) or frequency shift keying (FSK) in accordance with a communications protocol developed by the Society of Automotive Engineers (SAE) set forth in a document number J2497 and entitled Power Line Carrier Communications for Commercial Vehicles.The circuit 26 may include a signal acquisition circuit 30, an AC (alternating current) leveling circuit 32, a filter 34, a preamplifier 36, a peak detector circuit 38, an amplifier 40, an adjustable gain circuit 42, a comparator 44, and a bias circuit 46. The signal acquisition circuit 30 couples the signal conditioning circuit 26 to the power line 18. The circuit 30 may include a capacitor that couples the circuit 26 to the power line 18 and a blocking diode downstream of the capacitor, such as a Zener diode. It should be understood that the circuit 30 may take various forms and may implement inductive coupling of the circuit 26 to the power line 18 instead of capacitive coupling. AC leveling circuit 32 is provided to remove the direct current (DC) component from the signal received from signal acquisition circuit 30 and center the alternating current (AC) component to approximately zero (0) volts. Circuit 32 may include a capacitor. Filter 34 is provided to prevent the passage of analog input signals outside of certain frequencies. Filter 34 may be configured to prevent the passage of signals that are not intended for controller 28 and / or cannot be interpreted by controller 28 and may prevent the passage of signals subject to significant interference. Filter 34 may comprise a band-pass filter. zonn Ln / eznz / e / YiAi The preamplifier 36 is provided to strengthen the analog input signal before its supply to the amplifier 40. The preamplifier 36 is conventional in the art and receives signals output by the bandpass filter 34 and transmits signals to an input terminal of the amplifier 40. The peak detector circuit 38 identifies and measures amplitude peaks in the analog input signals. The circuit 38 is conventional in the art. The circuit 38 generates signals indicative of the amplitude corresponding to each analog input signal in response to signals generated by the preamplifier 36. The peak detector circuit 38 provides those signals to the controller 28 for a purpose discussed hereinafter. Amplifier 40 is configured to output amplified signals corresponding to the analog input signals, but having an increased amplitude. Amplifier 40 is conventional in the art. In accordance with one aspect of the disclosed embodiments, the gain applied by amplifier 40 to the analog input signal varies depending on the amplifier gain signal received from adjustable gain circuit 42. Amplifier 40 generates amplified signals responsive to the analog input signals (and, in particular, the signals received from preamplifier 36) and the amplifier gain signal. zonn Ln / eznz / B / YiAi The digital input signals provided to the controller 28 are then derived from the amplified signals. The adjustable gain circuit 42 is provided for varying the gain of the amplifier 40. The circuit 42 may comprise a digital potentiometer. The circuit 42 outputs an amplifier gain signal that establishes an amplifier gain level for the amplifier 40. The setting of the amplifier gain signal, and therefore the amplifier gain level, will vary in response to an amplifier gain control signal received from the controller 28. Comparator 44 is configured to generate digital input signals provided to controller 28 that are responsive to analog input signals received via power line 18, and in particular, amplified signals based on the analog input signals generated by amplifier 40. Comparator 44 compares the amplified signals from amplifier 40 to a bias signal generated by bias circuit 46 that establishes a DC (direct current) bias level. Comparator 44 is conventional in the art. The bias circuit 46 is provided for generating a bias signal that establishes a bias level for use in bias circuit elements within the comparator 44. In accordance with another aspect of the teachings described herein, the circuit 46 may be configured to vary the level and / or type of bias. The bias circuit 46 may include a linear bias circuit 48, an adjustable linear leveling circuit 50, an automatic bias circuit 52, and a bias selection circuit 54. The linear bias circuit 48 generates a linear bias signal having a preset bias level that is independent of the analog input signal and the amplified signal generated by the amplifier 40. The circuit 48 may comprise a voltage divider controlled by one or more digital potentiometers. The circuit 48 outputs the linear bias signal in response to a linear leveling signal output by the adjustable linear leveling circuit 50. The adjustable linear leveling circuit 50 generates a linear leveling signal configured to control the linear bias circuit 48 and the configuration of the linear bias signal and the bias level. The circuit 50 may comprise a digital potentiometer connected to a reference voltage source (not shown). The circuit 50 generates the linear leveling signal in response to the control signal from the controller 28. The auto-bias circuit 52 generates an auto-bias signal having a bias level that is dependent upon the analog input signal, and in particular, the amplified signal from amplifier 40. Circuit 52 is conventional in the art. Circuit 52 receives the signal generated by amplifier 40 and shapes the auto-bias signal in response to shift the bias level downward by a predetermined amount, thereby enabling a comparison within comparator 44 between the amplified signal and a signal similar to the amplified signal, but at a lower DC level. The bias selection circuit 54 is configured to output one of the linear bias signal and the auto-bias signal and deliver that signal to the comparator 44 as the bias signal. The circuit 54 may comprise one or more switches. The circuit 54 selects one of the linear bias signal and the auto-bias signal in response to a control signal from the controller 28. The controller 28 is provided for decoding messages received from the power line 18 and for encoding messages for transmission on the power line 18. The controller 28 may further be provided for performing a variety of actions in response to received messages depending upon the purpose of the system 20, 22 in which the controller 28 is employed. The controller 28 may comprise a programmable microprocessor or microcontroller or may comprise an application specific integrated circuit (ASIC). The controller 28 may include a memory 56 and a central processing unit (CPU) 58. The controller 28 may also include an input / output (I / O) interface 60 including a plurality of input / output pins or terminals through which the controller 28 can receive a plurality of input signals and transmit a plurality of output signals.The input signals may include signals received from the signal conditioning circuit 26, while the output signals may include signals transmitted to the power line 18 through, for example, a corresponding signal conditioning circuit that converts the digital output signals of the controller 28 to analog output signals. In the illustrated embodiment, a single controller 28 is shown. It should be understood, however, that the functionality of the controller 28 described herein may be divided among multiple subcontrollers. In accordance with the present teachings, the controller 28 may be configured with appropriate programming instructions (i.e., software or a computer program) to implement various steps in a method for calibrating signals received over the power line 18 described below. Referring now to Figure 3A, one embodiment of a method for calibrating signals received over power line 18 may begin with step 62 of setting the configuration of signal conditioning circuit 26 to a predetermined configuration. In performing step 62, controller 28 may generate control signals to one or more of adjustable gain circuit 42, linear adjustable leveling circuit 50, and bias selection circuit 54. In one embodiment, controller 28 generates a control signal to adjustable gain circuit 42 that controls the setting of the amplifier gain signal output by circuit 42 and the amplifier gain level to set the amplifier gain level in amplifier 40 to a predetermined level.The controller 28 further generates a second control signal for the adjustable linear leveling circuit 50 to control the shape of the linear bias signal output by the linear bias circuit 48 and set the linear bias level to a predetermined level. Finally, the controller 28 generates a third control signal for the bias selection circuit 54 which causes the circuit 54 to select the linear bias signal output by the linear bias circuit 48 as the bias signal input to the comparator 44. It should be understood that the predetermined settings for the signal conditioning circuit 26 may vary. The method may proceed to step 64 of determining whether to initiate the process for calibrating the signal conditioning circuit 26. Calibration of the Ln / eznz / B / γAΛA zonn circuit is most useful when there has been a change in a vehicle such as the semi-truck 10. For example, if a trailer 14 is added to the semi-truck 10, longer distance communications between some systems 20, 22 on the vehicle may be required. The increased distance may lead to attenuation of signals along the power line 18 and a reduction in the amplitude of some signals. In this situation, it may be desirable to increase the gain of amplifier 40 in the signal conditioning circuit 24 of one or more systems 20, 22. Conversely, if a trailer 14 is removed from the semi-truck 10, the farthest distance that signals are required to travel between any two systems 20, 22 on the semi-truck 10 may be reduced.In this situation, it may be desirable to decrease the gain of amplifier 40 in the signal conditioning circuit 24 of one or more systems 20, 22. Therefore, by performing step 64, the controller 28 may be configured to initiate the calibration process in response to conditions that may be indicative of a change in the vehicle. In the case of an articulated truck 10, the articulated truck is likely to transition from an active state (in which the battery 16 is providing electrical power to the power unit on the tractor 12 (e.g., an internal combustion engine or electric motor) to allow the power unit to begin generating the mechanical power required to turn the wheels of the vehicle 10) to an inactive state (in which the battery 16 is not providing electrical power to the power unit) before coupling or uncoupling a trailer 14 from the tractor 12.Thus, the controller 28 may be configured, for example, to initiate the calibration process each time the vehicle subsequently moves from an inactive state to an active state. The controller 28 may receive a signal indicative of whether the semitrailer 10 is in an active state or an inactive state from a variety of different sources. For example, sensors may provide signals to the controller 28 indicative of the position or state of a starter or ignition switch on the semitrailer 10 or the voltage or current supply from the battery 18 to the power unit. The engine or motor control system of the vehicle may also provide signals to the controller 28 indicative of the state of the power unit (e.g., if the engine is operating at 0 rpm, the vehicle is idling).Other systems, such as an anti-lock braking system, may stop transmitting certain signals when the vehicle is in an inactive state, and thus the absence of these signals may be indicative of an inactive state. In addition to initiating the calibration process when the vehicle moves from an inactive state to an active state, the controller 28 may initiate the calibration process under a variety of other conditions. The controller 28 may, for example, initiate the calibration process after a predetermined time interval has passed since a previous instance of the calibration process or after a predetermined time interval has passed during a period in which the semitrailer truck 10 is in an active state. The controller 28 may also initiate the calibration process in response to a condition inputted by an operator or owner of the vehicle via the I / O interface 60.If the controller 28 determines that calibration of the signal conditioning circuit 26 is not required, the method terminates. 3B , if the controller 28 determines that calibration of the circuit 26 should be initiated, the method may proceed to a step 66 of determining whether the current configuration of the circuit 26 (e.g., the default configuration set in step 62) is sufficient, and in particular, whether to adjust the amplifier gain level. Step 66 may include a plurality of sub-steps 68, 70, 72. In sub-step 68, the controller of claim 28 may receive a digital input signal generated by the comparator 44 of the circuit 26 in response to analog input signals received from the power line 18. In sub-step 70, the controller 28 may determine whether the digital input signal is a valid digital input signal. In one embodiment, a digital input signal is a valid digital input signal if the digital input signal has a frequency within a certain frequency range.It should be understood, however, that various conditions could be set to determine whether a digital input signal is a valid digital input signal. If the digital input signal is a valid input signal, the controller 28 may increment a valid signal counter in substep 72 and store the value in memory 56. Substeps 68, 70, 72 may be repeated until a predetermined condition is met. The condition may be, for example, that the controller 28 has received a predetermined number of signals or that a period of time has passed. Once the condition is met, the controller 28 may perform substep 74 wherein the controller 28 compares the number of valid digital input signals (as indicated by the counter stored in memory 56) to a threshold number to determine whether the number of valid digital input signals meets a predetermined condition (e.g., is greater than) the threshold number.If the controller 28 determines that the number of valid digital input signals meets the predetermined condition with respect to the threshold number, the method may terminate. Referring now to Figure 3C, if the controller 28 determines that the number of valid input digital signals does not meet the predetermined condition with respect to the threshold number, the method may continue to step 76 of optimizing the amplifier gain level of the amplifier 40. Step 76 may include a number of sub-steps 78, 80, 82, 84, 86, 88, 90, 92, 94, 96. In order to optimize the amplifier gain level, the controller 28 may be configured to set the amplifier gain level to a plurality of different levels and test the impact of each gain level on the conversion of the analog input signal to the digital input signals received by the controller 28.Thus, in sub-step 78, controller 28 may set a counter to a predetermined number corresponding to the number of different amplifier gain levels (and different configurations for circuit 26) to be tested by controller 28. In sub-steps 80 and 82, the controller 28 determines the largest amplitude and the smallest amplitude, respectively, obtained by the plurality of analog input signals corresponding to the plurality of digital input signals obtained during the repeated performance of sub-step 68 of step 66. The controller 28 may receive signals from the peak detector circuit 38 indicative of the amplitude of each analog input signal that is finally converted into a digital input signal by the circuit 26 and received by the controller 28. The controller 28 may store values ​​indicative of the amplitude of each analog input signal in the memory 56 and determine the largest and smallest amplitude Ln / eznz / Β / γAΛA from among all the stored values.Alternatively, the controller 28 may store a single larger amplitude value and a single smaller amplitude value in the memory 56 and overwrite these values ​​as needed in response to ongoing comparisons of the stored values ​​against the value indicated by each signal received from the peak detector circuit 38 as that signal is received. In sub-step 84, controller 28 sets the amplifier gain level in response to the largest amplitude and smallest amplitude identified in sub-steps 80, 82. Controller 28 may, for example, determine the difference between the largest and smallest amplitudes or an average of the largest and smallest amplitudes. Using this difference or average, controller 28 may access a data structure such as a lookup table in a memory such as memory 56 that correlates the amplitude difference or average to a predetermined amplifier gain level. In sub-step 86, controller 28 then generates a control signal and transmits that control signal to adjustable gain circuit 42 causing circuit 42 to output an amplifier gain signal to amplifier 40 which establishes the predetermined amplifier gain level in amplifier 40. Once the new amplifier gain level Ln / eznz / Β / γAΛA is established, the controller 28 performs a series of sub-steps 88, 90, 92, similar to sub-steps 68, 70, 72, in step 66 discussed above. In particular, in sub-step 88, the controller 28 may receive a digital input signal generated by the comparator 44 of the circuit 26 in response to analog input signals received from the power line 18. In sub-step 90, the controller 28 may determine whether the digital input signal is a valid digital input signal. In one embodiment, a digital input signal is a valid digital input signal if the digital input signal has a frequency within a certain frequency range. It should be understood, however, that various conditions could be set to determine whether a digital input signal is a valid digital input signal. If the digital input signal is a valid input signal,Controller 28 may, in substep 92, increment a valid signal counter and store the number in memory 56. Substeps 88, 90, 92 may be repeated again until a predetermined condition is met. The condition may be, for example, that controller 28 has received a predetermined number of signals or that a period of time has passed. Once the condition is met, controller 28 may perform substep 94 wherein controller 28 determines whether the counter value set in substep 78 meets a predetermined condition with respect to a predetermined number (e.g., if the counter value is equal to zero). If controller 28 determines in substep 94 that the counter value does not meet the predetermined condition with respect to the predetermined number, controller 28 may adjust the counter value (e.g., decrement the counter) in substep 96,return to sub-step 80 and repeat sub-steps 80, 82, 84, 86, 88, 90, 92, 94 so that controller 28 determines the largest amplitude and the smallest amplitude, respectively, obtained by the plurality of analog input signals corresponding to the plurality of digital input signals obtained during the repeated performance of sub-step 88 in the original iteration of step 76, sets the amplifier gain level in response to the largest amplitude and the smallest amplitude, receives another plurality of digital input signals in response to another plurality of analog input signals received from power line 18, determines whether each of these digital input signals is a valid digital input signal and, if so, increments a valid signal counter and stores the number in memory 56, and, once the predetermined condition relating to signal capture is met,again determines whether the counter value set in sub-step 78 meets the predetermined condition relative to the predetermined number (e.g., whether the counter value zonn Ln / eznz / Β / γAΛA is equal to zero)., Once the controller 28 determines in sub-step 94 that the counter value meets the predetermined condition with respect to the predetermined number, the controller 28 may proceed to sub-step 98 wherein the controller 28 sets the optimized amplifier gain level in response to the numbers obtained during the repeated instances of sub-step 92. The controller 28, for example, may identify the largest number among the plurality of numbers obtained during the repeated instances of sub-step 92 at each amplifier gain level to determine which amplifier gain level provided the greatest number of valid digital input signals.The controller 28 may then generate a control signal in sub-step 100 and transmit that control signal to the adjustable gain circuit 42 causing the circuit 42 to output an amplifier gain signal to the amplifier 40 which establishes the optimized amplifier gain level in the amplifier 40. The controller 28 may also store the optimized gain level in the memory 56 in sub-step 102 for use in establishing the default configuration of the circuit 24 in step 52 during subsequent iterations of the method. Referring now to Figure 3D, after the step 104 of optimizing the amplifier gain level of the amplifier 40, the controller 28 may, in certain embodiments, perform the additional step 104 of optimizing the bias level in the comparator 44 of the circuit 26. The step 104 may again include a plurality of sub-steps 106, 108, 110, 112, 114, 116, 118, 122, 124, 126. In order to optimize the bias level, the controller 28 may be configured to first set the linear bias level generated by the linear bias circuit 48 of the bias circuit 46 to a plurality of different levels and test the impact of each linear bias level on the conversion of the analog input signal to the digital input signals received by the controller 28.Thus, in sub-step 106, the controller 28 may set a counter to a predetermined number corresponding to the number of different linear bias levels (and different settings for the circuit 26) to be tested by the controller 28. Thereafter, in sub-steps 108 and 110, the controller 28 may set a linear bias level in the linear bias circuit 48 and then generate a control signal and transmit that signal to the linear bias adjustment circuit 50 which in turn generates a linear leveling signal that controls the setting of the linear bias signal output by the linear bias circuit 48 and the linear bias level.Initially, the controller 28 may cause the linear bias circuit 48 to generate a linear bias signal that establishes a linear bias level corresponding to the linear bias level set in the default configuration of the signal conditioning circuit in step 52. After establishing the initial linear bias level, the controller 28 may, in substep 112, again receive a digital input signal generated by the comparator 44 of the circuit 26 in response to analog input signals received from the power line 18. In substep 114, the controller 28 may determine whether the digital input signal is a valid digital input signal. In one embodiment, a digital input signal is a valid digital input signal if the digital input signal has a frequency within a certain frequency range. It should be understood, however, that various conditions could be set to determine whether a digital input signal is a valid digital input signal. If the digital input signal is a valid input signal, the controller 28 may increment a valid signal counter in substep 116 and store the number in memory 56. Substeps 112, 114,116 may be repeated until a predetermined condition is met. The condition may be, for example, that the controller 28 has received a predetermined number of signals or that a period of time has passed. Once the condition is met, the controller 28 may proceed to substep 118 in which the controller 28 determines whether the counter value set in substep 106 meets a predetermined condition with respect to a predetermined number (e.g., whether the counter value is equal to zero). If the controller 28 determines in sub-step 118 that the counter value does not meet the predetermined condition with respect to the predetermined number, the controller 28 may adjust the counter value (e.g., decrement the counter) in sub-step 120. The controller 28 then returns to sub-step 108 and repeats sub-steps 108, 110, 112, 114, 116, 118,so that the controller 28 establishes a new linear bias level in sub-step 108, transmits a control signal to the adjustable linear leveling circuit 50 in sub-step 110 to cause the circuit 48 to generate a linear bias signal at the new linear bias level, receives another plurality of digital input signals in response to another plurality of analog input signals received from the power line 18 in sub-step 112, determines whether each of these digital input signals is a valid digital input signal in sub-step 114 and, if so, increments a valid signal counter in sub-step 116 and stores the value in memory 56, and, once the predetermined condition related to signal capture is met, again determines in sub-step 118 whether the counter value meets the predetermined condition relative to the predetermined number (e.g.,If the zonn Ln / eznz / B / YiAi counter value is equal to zero). In performing each instance of substep 108, the controller 28 may be configured to adjust the linear bias level in a predetermined manner. For example, the controller 28 may increment or decrement the linear bias level by a predetermined amount each time (resulting in a linear or non-linear change in the linear bias level). Once the controller 28 determines in sub-step 118 that the counter value meets the predetermined condition with respect to the predetermined number, the controller 28 may proceed to step 122 wherein the controller 28 establishes an optimized linear bias in response to the numbers obtained during the repeated instances of sub-step 116. The controller 28, for example, may identify the largest number among the plurality of numbers obtained in sub-step 116 at each linear bias level to determine which linear bias level provided the greatest number of valid digital input signals. In sub-step 124, the controller 28 may then generate a control signal and transmit that control signal to the adjustable linear leveling circuit 50 causing the linear bias circuit 48 to output a linear bias signal that establishes the optimized linear bias in the comparator 44.The controller 28 may also store the optimized linear bias level in memory 56 in sub-step 126 for use in establishing the default configuration of the circuit 26 in step 52 during subsequent iterations of the method. Referring now to Figure 3E, in some embodiments, step 104 of optimizing the bias level may include selecting one of a linear bias signal generated by the linear bias circuit 48 and an auto-bias signal generated by the auto-bias circuit 52 as the bias signal. In these embodiments, step 104 may further include sub-steps 128, 130, 132, 134. In sub-step 128, the controller 28 may generate a bias control signal and transmit the signal to the bias selection circuit 54 to select the auto-bias signal from the auto-bias circuit 52 as the bias signal provided to the comparator 44. In sub-step 130, the controller 28 may again receive a digital input signal generated by the comparator 44 from the circuit 26 in response to analog input signals received from the power line 18.In substep 132, controller 28 may determine whether the digital input signal is a valid digital input signal. In one embodiment, a digital input signal is a valid digital input signal if the digital input signal has a frequency within a certain frequency range. It should be understood, however, that various conditions could be set to determine whether a digital input signal is a valid digital input signal. If the digital input signal is a valid input signal, controller 28 may increment a valid signal counter in substep 134 and store the value in memory 56. Substeps 130, 132, 134 may be repeated until a predetermined condition is met. The condition may be, for example, that controller 28 has received a predetermined number of signals or that a period of time has passed. Once the condition is met, the controller 28 may proceed to sub-step 136 wherein the controller 28 compares the number obtained in sub-step 126 and associated with the optimized linear bias level with the number obtained in sub-step 134 and associated with the auto-bias level. If the controller 28 determines that the number associated with the optimized linear bias level is greater than the number associated with the auto-bias level, the controller 28 generates a control signal in step 138 configured to cause the bias selection circuit 54 to select the linear bias signal output by the linear bias circuit 48 and direct the linear bias signal to the comparator 44.Alternatively, if the controller 28 determines that the number associated with the auto-bias level is greater than the number associated with the optimized linear bias level, the controller 28 generates a control signal at step 140 configured to cause the bias selection circuit 54 to select the auto-bias signal Ln / eznz / B / YiAi output by the auto-bias circuit 52 and direct the auto-bias signal to the comparator 44. A system 24 and method for calibrating signals received over a power line 18 within a vehicle in accordance with the present teachings represents an improvement over conventional systems and methods. In particular, embodiments of the system 24 and method described herein allow for adjustment of the amplifier gain in the signal conditioning circuit 26 thereby ensuring that the associated controller 28 will receive signals generated by other controllers located at varying distances from the controller 28 in the vehicle. Embodiments of the system 24 and method described herein may alternatively, or in addition, allow for adjustment of the level and type of bias applied to the received signals, allowing the system to optimize signal bias. While the invention has been shown and described with reference to one or more particular embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. It is noted that in relation to this date, the best method known to the applicant to put the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A system for calibrating signals received over an electrical line within a vehicle, comprising: a signal conditioning circuit configured to convert analog input signals received over the electrical line in the vehicle into digital input signals, including an adjustable gain circuit configured to output an amplifier gain signal that sets an amplifier gain level; and an amplifier configured to output amplified signals responsive to the analog input signals and the amplifier gain signal, the digital input signals formed in response to the amplified signals; and a controller configured to receive the digital input signals;and, generate control signals configured to control the configuration of the amplifier gain signal output by the adjustable gain circuit and the amplifier gain level Ln / eznz / Β / γAΛA.; 2. The system according to claim 1, characterized in that the controller is further configured to determine whether to adjust the amplifier gain level.

3. The system of claim 2, wherein the controller is further configured to determine whether to adjust the amplifier gain level, to: receive a plurality of the digital input signals; determine a number of valid digital input signals from among the plurality of digital input signals; and compare the number to a threshold number.

4. The system according to claim 1, characterized in that the controller is further configured to optimize the amplifier gain level.

5. The system according to claim 4, characterized in that the controller is further configured to optimize the amplifier gain level, for: receiving a first plurality of the digital input signals corresponding to a first plurality of the analog input signals; determining the largest amplitude obtained by the first plurality of the analog input signals; zonn Ln / eznz / Β / γAALA determining the smallest amplitude obtained by the first plurality of the analog input signals; setting the amplifier gain level to a first amplifier gain level in response to the largest amplitude and the smallest amplitude.

6. The system of claim 5, wherein the controller is further configured to optimize the amplifier gain level by: receiving a second plurality of digital input signals corresponding to a second plurality of analog input signals after setting the amplifier gain level to the first amplifier gain level; determining a first number of valid digital input signals from among the second plurality of digital input signals; and storing the first number in a memory.

7. The system according to claim 6, characterized in that the controller is further configured to optimize the amplifier gain level, to determine the largest amplitude obtained by the second plurality of analog input signals; determine the smallest amplitude obtained by the second plurality of analog input signals; zonn Ln / eznz / Β / γAALA setting the amplifier gain level to a second amplifier gain level in response to the largest amplitude obtained by the second plurality of analog input signals and the smallest amplitude obtained by the second plurality of analog input signals; receive a third plurality of digital input signals corresponding to a third plurality of analog input signals after setting the amplifier gain level to the second amplifier gain level;determining a second number of valid input digital signals from among the third plurality of input digital signals; storing the second number in a memory; and, setting the amplifier gain level in response to the first and second numbers.

8. A system for calibrating signals received via an electrical line within a vehicle, comprising: a signal conditioning circuit configured to convert analog input signals received via the electrical line in the vehicle into digital input signals including a bias circuit configured to output a bias signal that establishes a bias level; and, a comparator configured to generate digital input signals responsive to the analog input signals and the bias signal; and, a controller configured to receive the digital input signals; and, generate one or more control signals configured to control the configuration of the bias signal output by the bias circuit and the bias level.

9. The system of claim 8, wherein the bias circuit includes: an adjustable linear leveling circuit configured to output a linear leveling signal responsive to a first control signal from the one or more control signals from the controller; and, a linear bias circuit configured to output a linear bias signal responsive to the linear leveling signal.

10. The system according to claim 9, characterized in that the bias circuit includes: an automatic bias circuit configured to output an automatic bias signal; and, a bias selection circuit configured to output one of the linear bias signal and the automatic bias signal as the bias signal in response to a second control signal Ln / eznz / Β / γAΛA of the one or more control signals from the controller.

11. The system according to claim 8, characterized in that the controller is further configured to optimize the level of bias.

12. The system of claim 11, wherein the controller is further configured to optimize the skew level by: receiving a first plurality of the digital input signals from the comparator when the skew level is at a first skew level; determining a first number of valid digital input signals from the first plurality of digital input signals; changing the skew level from the first skew level to a second skew level different from the first skew level; receiving a second plurality of the digital input signals from the comparator when the skew level is at the second skew level; determining a second number of valid digital input signals from the second plurality of digital input signals; and, determining an optimized skew level in response to the first and second numbers.

13. The system according to claim 11, characterized in that the controller is further configured to optimize the bias level, to select one of a linear bias signal generated by a linear bias circuit and an automatic bias signal generated by an automatic bias circuit as the bias signal.

14. The system of claim 13, wherein the controller is further configured, upon selecting one of the linear bias signal and the auto-bias signal, to: receive a first plurality of the input digital signals from the comparator when the bias signal is the linear bias signal; determine a first number of valid digital input signals from among the first plurality of digital input signals; receive a second plurality of the input digital signals from the comparator when the bias signal is the auto-bias signal; determine a second number of valid input digital signals from among the second plurality of input digital signals; and, compare the first number with the second number.

15. A system for calibrating signals received over an electrical line within a vehicle, comprising: a signal conditioning circuit configured to convert analog input signals received over the electrical line in the vehicle into digital input signals including an adjustable gain circuit configured to output an amplifier gain signal that establishes an amplifier gain level; and, an amplifier configured to output amplified signals responsive to the analog input signals and the amplifier gain signal; a bias circuit configured to output a bias signal that establishes a bias level; and, a comparator configured to generate the digital input signals responsive to the amplified signals and the bias signal; and, a controller configured to receive the input digital signals;and, generating one or more amplifier gain control signals configured to control the configuration of the amplifier gain signal output by the adjustable gain circuit and the amplifier gain level. generating one or more bias control signals configured to control the configuration of the bias signal output by the bias circuit and the bias level.

16. The system of claim 15, wherein the controller is further configured to optimize the amplifier gain level, the controller being further configured to optimize the amplifier gain level, to: receive a first plurality of the digital input signals; determine the largest amplitude obtained by the first plurality of digital input signals; determine the smallest amplitude obtained by the first plurality of digital input signals; set the amplifier gain level in response to the largest amplitude and the smallest amplitude.

17. The system of claim 15, wherein the bias circuit includes: an adjustable linear leveling circuit configured to output a linear leveling signal responsive to a first control signal of the one or more bias control signals from the controller; and, a linear bias circuit configured to output a linear bias signal responsive to the linear leveling signal.

18. The system of claim 17, wherein the biasing circuit includes: an auto-biasing circuit configured to output an auto-bias signal; and, a bias selection circuit configured to output one of the linear bias signal and the auto-bias signal as the bias signal in response to a second control signal of the one or more bias control signals from the controller.

19. The system according to claim 15, characterized in that the controller is further configured to optimize the bias level and the controller is further configured, to optimize the bias level, to select one of a linear bias signal generated by a linear bias circuit and an automatic bias signal generated by an automatic bias circuit as the bias signal.

20. The system of claim 19, wherein the controller is further configured, upon selecting one of the linear bias signal and the auto-bias signal, to: receive a first plurality of the input digital signals from the comparator when the bias signal is the linear bias signal; determine a first number of valid digital input signals from the first plurality of digital input signals; receive a second plurality of the input digital signals from the comparator when the bias signal is the auto-bias signal; determine a second number of valid input digital signals from the second plurality of input digital signals; and, compare the first number with the second number.

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