PWM Signal Conversion for Isolated Analog Current Range Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing signal processing systems face limitations in scaling analog signals across electrically isolated instruments with different signaling schemes, leading to errors when instruments operate on different current ranges, such as 4-20 mA and 12-20 mA scales.
Innovation Solution
A signal processor that converts a first analog signal into a digital signal, generates a scaled pulse width modulation signal based on the digital signal, and converts it back into a second analog signal, accommodating differences in analog signal encoding between instruments and bus loops through runtime scaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optically coupled circuits are used to transmit signals between electrically isolated instruments, then electrical isolation is achieved, but signal scaling capability is limited
Solution Approach 1:
The patent introduces a signal processor as an intermediary device between the optically coupled circuit and the bus loop. This processor receives the transmitted signal, performs scaling operations using lookup tables or computational algorithms, and outputs the scaled signal. The intermediary handles the complexity of signal adaptation, allowing the optically coupled circuit to maintain electrical isolation while the processor provides the necessary signal scaling versatility.
Solution Approach 2:
The signal processor implements dynamic scaling by using runtime-configurable lookup tables and computational algorithms that can adapt to different signal ranges. The system can be reconfigured to handle various analog signal encodings (e.g., 4-20 mA, 0-20 mA, 12-24 V) without hardware changes, providing dynamic adaptability while maintaining the stable electrical isolation of the optical coupling.
2Adaptability or versatility
If instruments operate on different current ranges (e.g., 4-20 mA vs. 12-20 mA), then instrument versatility is improved, but signal transmission accuracy deteriorates
Solution Approach 1:
The signal processor changes the parameters of the transmitted signal by applying scaling factors to convert between different current ranges. Lookup tables store pre-calibrated scaling parameters for various input/output range combinations, and computational algorithms dynamically calculate the appropriate scaling factors. This parameter transformation ensures that signals from instruments operating on different current ranges are accurately converted, maintaining measurement precision while supporting instrument versatility.
3Adaptability or versatility
If signal scaling is performed to accommodate different analog signal encodings, then adaptability is improved, but device complexity increases
Solution Approach 1:
The signal processor performs preliminary scaling actions by pre-calculating and storing scaling parameters in lookup tables. These tables contain pre-computed conversion factors for common analog signal encoding combinations. When a signal needs scaling, the processor simply retrieves the appropriate parameters from the lookup table and applies them, avoiding complex real-time calculations and reducing processing complexity while maintaining high adaptability.
Solution Approach 2:
The system uses lookup tables that store copied and pre-processed scaling parameters for various signal encoding combinations. Instead of performing complex calculations for each signal conversion, the processor copies the appropriate scaling parameters from the lookup table and applies them. This approach simplifies the processing complexity while maintaining the ability to handle multiple signal encoding types.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate signal transmission by scaling the bit-stream to match the output analog signal encoding, preventing errors caused by mismatched signaling schemes and allowing operation with multiple sensors in different environments.
Implementation Method 1
transmit the pulse width modulation signal across an electrical barrier using an optocoupler
Data Source
AI summary
A signal processor (30) is provided. The signal processor (30) is configured to receive a first analog signal and convert the first analog signal into a digital signal. The digital signal is transmitted across an electrical barrier and converted into a scaled pulse width modulation signal. The scaled pulse width modulation signal is then converted into a scaled second analog signal, which is output by the signal processor (30).