Contactless Data Link Adjustment for Rotating Joints
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Solution Overview
Problem
Contactless data links used in rotating units, such as CT scanners and industrial machines, face limitations in achieving high data rates while maintaining high noise immunity and low transmission losses, requiring specific adjustment procedures to meet EMC standards.
Innovation Solution
A contactless data link system with a transmitter and receiver, utilizing differential stripline conductors, impedance matching, and amplifiers, along with a test setup for adjusting the spatial relationship between the receiver antenna and transmission lines, to optimize noise immunity and electromagnetic suppression performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the transmission line bandwidth is increased to achieve higher data rates, then the data rate is improved, but noise immunity deteriorates and electromagnetic interference increases
Solution Approach 1:
The transmission line is segmented into multiple sections with different characteristic impedances (e.g., 50 ohm, 75 ohm, 100 ohm sections) along its length. This segmentation creates a bandpass filter effect that allows the desired data transmission frequencies to pass while attenuating out-of-band noise and interference, thus improving noise immunity while maintaining high data rates
Solution Approach 2:
The characteristic impedance of the transmission line is varied along its length by changing geometric parameters (conductor width, spacing, substrate height) to create different impedance sections. This parameter variation implements frequency-selective filtering that enhances noise rejection while preserving the bandwidth needed for high data rate transmission
2Speed
If the transmission line bandwidth is increased to achieve higher data rates, then the data rate is improved, but transmission losses increase
Solution Approach 1:
The characteristic impedance is optimally varied along the transmission line to minimize reflections and maximize power transfer efficiency at the desired data transmission frequencies. By carefully designing the impedance profile, the system achieves high data rates with reduced transmission losses through improved signal integrity
Solution Approach 2:
The transmission line is divided into impedance-matched sections that progressively transition the signal, reducing abrupt impedance changes and associated reflections. This segmented approach minimizes standing waves and energy loss while maintaining the bandwidth required for high data rate operation
3Reliability
If the receiver antenna is positioned closer to the transmission line to improve signal coupling, then signal strength is improved, but electromagnetic interference and noise immunity deteriorate
Solution Approach 1:
The transmission line has non-uniform characteristic impedance distributed along its length, creating different electromagnetic field characteristics in different sections. This allows the receiver antenna to be positioned at a specific location where the field coupling is optimal for signal strength while the varying impedance profile simultaneously provides frequency-selective filtering that rejects out-of-band electromagnetic interference
Solution Approach 2:
The transmission line is segmented into sections with different impedance values, creating a distributed filtering effect. This segmentation allows the antenna to be positioned close to certain sections for strong signal coupling while the overall impedance profile attenuates electromagnetic interference, achieving both goals simultaneously
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
The system achieves increased data rates with improved noise immunity and low bit error rates, allowing for efficient data transmission in rotating applications like CT scanners, with adjustment procedures that significantly reduce measurement time and ensure optimal signal quality.
Implementation Method 1
The transmitter amplifier feeds signals into the at least one transmission line
Implementation Method 2
signals are coupled between the at least one transmission line and the receiver antenna
Implementation Method 3
which are further amplified by at least one receiver amplifier
Data Source
AI summary
A test setup for testing a contactless digital rotary joint integrated in a device requiring data transmission between a rotating part and a stationary part, the rotary joint further comprises a transmitter and a receiver. The transmitter has a transmitter amplifier, which is coupled to a pair of transmission lines, which are terminated by a pair of terminations. The transmission lines are differential transmission lines comprising a pair of conductors which is driven by differential signals from the transmitter amplifier. The receiver has a receiver antenna comprising a pair of antenna sections which are differentially operated and feed a differential signal to the receiver amplifier. A transmitter ground and a receiver ground are coupled to a common mode signal generator generating a common mode signal. A data source is coupled to the transmitter amplifier feeding a test signal into the transmitter amplifier, and a data sink is coupled to the receiver amplifier for receiving the test signal and generating a test result value. Also disclosed is a method for adjusting a contactless data link integrated in a device requiring data transmission between a rotating part and a stationary part.