Isolated Sensor Interface Using Modulated Clock Data Acquisition
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Solution Overview
Problem
In measurement data acquisition systems, analog measurement signals often deteriorate due to distance and harsh electrical conditions, making it challenging to maintain accurate representations of physical quantities, especially when processing units are not in close proximity to sensors and electrical conditions vary wildly.
Innovation Solution
Implementing a method where a control unit communicates with sensor units across an isolation barrier using a modulated clock signal to transmit control information, allowing for efficient data acquisition and power management, while an analog-to-digital converter is biased to a sensor reference voltage to maintain stability, and using a multiplexer to combine signals from multiple sensor units for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the processing unit is placed at a distance from the transducer, then the system layout flexibility is improved, but the analog measurement signal deteriorates due to damping and noise on the transmission line
Solution Approach 1:
An isolation barrier is introduced as an intermediary component between the sensor unit and control unit. This barrier contains isolated interfaces that electrically separate the two sides while maintaining communication capability, thus protecting the analog measurement signal from deterioration due to distance and harsh electrical conditions
Solution Approach 2:
The patent replaces direct electrical connection with magnetic coupling through the isolation barrier. The first interface uses a transformer coupling mechanism where magnetic fields transfer signals across the barrier without direct electrical contact, eliminating the problem of signal deterioration over distance
2Reliability
If an isolation barrier is provided to separate reference voltages, then the system operates reliably under varying electrical conditions, but the device complexity increases due to additional interface requirements
Solution Approach 1:
The first interface is designed to perform multiple functions simultaneously: it provides galvanic isolation, transmits analog measurement signals bidirectionally, and maintains reference voltage separation. This multi-functionality reduces the need for separate components and simplifies the overall system architecture
Solution Approach 2:
The patent combines the isolation barrier with the interface circuitry into an integrated structure. The transformer coupling mechanism is merged with the signal transmission path, eliminating the need for separate isolation and transmission components
3Reliability
If additional control signal lines are provided for communication across the barrier, then the control information transmission is reliable, but the device complexity and wiring requirements increase
Solution Approach 1:
The existing signal lines are designed to carry multiple types of information. The same physical connection transmits both analog measurement signals and control information by utilizing different signal characteristics and timing, thus eliminating the need for separate dedicated control lines
Data Source
AI summary
Methods for use in a measurement system. Some embodiments comprise, at control unit, receiving a clock receive signal that represents a clock signal and configuration information; based on the clock receive signal, providing a control signal that represents the configuration information; and transmitting the control signal a sensor unit. Some embodiments comprise configuring the sensor unit according to the configuration information. Some embodiments comprise, at a control unit, configured to process data provided by the sensor unit. The method comprises receiving a data receive signal and selecting an interpretation of the data receive signal as one of at least: the sensor data signal and another data signal. Further disclosed herein are an interface, a control unit and a sensor unit for use in a measurement system.