This invention relates to signal conditioning. In particular, the invention relates to a circuit and method for adjusting the amplitude of an analog input signal to a level suitable for further processing of the signal.
Analog electrical signals that are received by or input to certain systems may have amplitudes having a large dynamic range. For example, Power Line Communication (PLC) is a communication method in which data is transmitted over wires that are also used to deliver electric power. The data is encoded within a signal that is transmitted over the wires in frequency ranges outside of those used to transmit electric power. PLC is advantageous relative to other communication methods because it enables communication using existing wiring. Tractor-trailers frequently employ PLC to exchange messages between members of the tractor-trailer including, for example, sensor readings from vehicle systems including anti-lock braking systems, collision avoidance systems, tire pressure monitoring systems and other vehicle systems as well as commands used to control anti-lock braking systems, lighting systems and other vehicle systems. In accordance with the communications protocol developed by the Society of Automotive Engineers (SAE) and set forth in a document number J2497 and titled “Power Line Carrier Communications for Commercial Vehicles”, PLC signals have a large dynamic range with signals have voltages between five (5) millivolts peak-to-peak and seven thousand (7000) millivolts peak-to-peak. Because of the large dynamic range of such signals, the amplitude must be adjusted prior to processing (e.g., demodulation and decoding) of the signals to allow for processing in a reliable and efficient manner.
Conventional circuits and methods for adjusting signal amplitude frequently employ complex integrated circuits that require repeated conversions of the analog signal to a digital signal and from a digital signal back to an analog signal. Conventional circuits and methods also frequently require multiple stages of amplification or attenuation to amplify or attenuate a signal. Conventional circuits and methods also frequently compare signal amplitude against one or more thresholds in deciding whether or not to adjust the amplitude creating delays in further processing of the signal.
The inventors herein have recognized a need for a circuit and method for adjusting an amplitude of an analog input signal that will minimize and/or eliminate one or more of the above-identified deficiencies.
This invention relates to signal conditioning. In particular, the invention relates to a circuit and method for adjusting the amplitude of an analog input signal to a level suitable for further processing of the signal.
One embodiment of a circuit for adjusting an amplitude of an analog input signal includes an amplifier configured to receive the analog input signal and to output an analog output signal responsive to the analog input signal and a gain control signal. The circuit further includes a gain control signal generator configured to receive the analog input signal and to generate the gain control signal responsive to the analog input signal.
Another embodiment of a circuit for adjusting an amplitude of an analog input signal includes an amplifier configured to receive the analog input signal and to output an analog output signal responsive to the analog input signal and a gain control signal. The circuit further includes means for generating the gain control signal, the generating means configured to receive the analog input signal and to generate the gain control signal responsive to the analog input signal.
One embodiment of a method for adjusting an amplitude of an analog input signal includes receiving an analog input signal as an input to an amplifier and a gain control signal generator. The method further includes generating a gain control signal in the gain control signal generator responsive to the analog input signal. The method further includes outputting an analog output signal from the amplifier responsive to the analog input signal and the gain control signal.
A circuit and method for adjusting an amplitude of an analog input signal in accordance the present teachings represent an improvement as compared to conventional circuits and methods. In particular, the circuit and method disclosed herein employ less complex circuitry than conventional circuits and avoid the need for conversion of the analog signal to a digital signal and back to an analog signal. The circuit and method also adjust the amplitude in a single stage. Finally, the circuit and method avoid comparisons of the signal amplitude to predetermined thresholds and the resulting delays in adjustment of the amplitude and signal processing.
The foregoing and other aspects, features, details, utilities, and advantages of the present invention will be apparent from reading the following description and claims, and from reviewing the accompanying drawings.
Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views,
Tractor 12 and trailers 14 may include various fluid and power lines that extend between tractor 12 and trailers 14 including power line 18. The fluid and power lines allow delivery of fluids and electrical power from tractor 12 to trailers 14 for use in, for example, tire pressure management, braking, and activation of tail lights on trailer 14. Power line 18 also forms part of a network used to transmit communications between various electronic systems 20, 221 . . . 22N on tractor 12 and trailers 14, respectively. Systems 20, 22 may comprise any of a wide variety of systems commonly employed on tractor-trailer 10 including, for example, anti-lock braking systems, collision avoidance systems, tire pressure monitoring and control systems, trailer load monitoring systems, and lighting systems. Power line 18 may enable transmission of data from one or more systems 22 on trailers 14 to a system 20 on tractor 12 including, for example, sensor readings indicative of the operation of an anti-lock braking system, the location of surrounding vehicles and infrastructure, pressure within the tires on a trailer 14, or a shift in the load carried by a trailer 14. Power line 18 may also enable transmission of commands and data from tractor 12 to trailers 14 for use in controlling elements of an anti-lock braking system, tire pressure control system or lighting system on one or more of trailers 14.
Messages containing data and/or commands may be transmitted along power line 18 between systems 20, 22 using the communications protocol developed by the Society of Automotive Engineers (SAE) and set forth in the document number J2497 and titled “Power Line Carrier Communications for Commercial Vehicles.” In accordance with this protocol, the messages are encoded and transmitted as analog signals having a large dynamic range. In particular, the signals have voltages between five (5) millivolts peak-to-peak and seven thousand (7000) millivolts peak-to-peak. In order to reliability and efficiently process these signals, the amplitude of a received signals often requires adjustment (amplification or attenuation) prior to further processing of the signal.
Referring now to
Amplifier 28 is configured to receive an analog input signal 26 and to output an analog output signal 34 that may have a different amplitude (i.e., amplified or attenuated) than the analog input signal 26. Amplifier 28 may for example, comprise the eight-pin operational amplifier offered by Texas Instruments, Inc. under part number LM318. Amplifier 28 receives two input signals—the analog input signal 26 (at pin 3 in the illustrated embodiment) and the gain control signal 32 (at pin 2 in the illustrated embodiment) from gain control signal generator 30. In response to these signals, amplifier 28 outputs an analog output signal 34 (at pin 6 in the illustrated embodiment). In accordance with the teachings disclosed herein, the amplitude of the analog output signal 34 will be increased relative to the amplitude of the analog input signal 26 when the amplitude of the analog input signal 26 is below a predetermined level. Conversely, the amplitude of the analog output signal 34 will be decreased relative to the amplitude of the analog input signal 26 when the amplitude of the analog input signal 26 is above the predetermined level. The amplitude of the analog output signal 34 will equal the amplitude of the analog input signal 26 when the amplitude of the analog input signal 26 is equal to the predetermined level. The predetermined level may be varied depending on the application and is reflected in the configuration of gain control signal generator 30 described below.
Gain control signal generator 30 provides means for generating a gain control signal 32 to control adjustment of the amplitude of the analog input signal 26 by amplifier 28. In accordance with the teachings disclosed herein, gain control signal generator 30 generates the gain control signal 32 responsive to the analog input signal 26 and the analog input signal 26 is the only variable in formulating the gain control signal 32. Referring to
Referring to
The configuration of gain control signal generator 30 produces a gain control signal 32 establishing a gain in amplifier 28 that is inversely proportional to the amplitude of the analog input signal 26. In particular, JFET 36 functions as a variable resistor with the resistance between the drain and source of JFET 36 increasing as the voltage between the gate of JFET 36 and source of JFET 36 increases. The voltage between the gate and source of JFET 36 is determined by the voltage of analog input signal 26. Therefore, as the voltage, and amplitude, of analog input signal 26 increases, the resistance of JFET 36 increases and the resulting gain control signal 32 provided to amplifier 28 establishes a gain in amplifier 28 that is inversely proportional to the amplitude of analog input signal 26. Referring to
Referring again to
A circuit 24 and method for adjusting an amplitude of an analog input signal 26 in accordance the present teachings represent an improvement as compared to conventional circuits and methods. In particular, the circuit 24 and method disclosed herein employ less complex circuitry than conventional circuits and avoid the need for conversion of the analog input signal 26 to a digital signal and back to an analog signal. The circuit 24 and method also adjust the amplitude in a single stage. Finally, the circuit 24 and method avoid comparisons of the signal amplitude to predetermined thresholds and the resulting delays in adjustment of the amplitude and signal processing.
While the invention has been shown and described with reference to one or more particular embodiments thereof, it will be understood by those of skill in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
Number | Date | Country | Kind |
---|---|---|---|
202341080924 | Nov 2023 | IN | national |