Spread Spectrum Clock Signal for Fieldbus Interference Reduction
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Solution Overview
Problem
Existing fieldbus systems face challenges in maintaining synchronization and reducing electromagnetic interference during fast binary data transmission, particularly due to differences in local clock signals and the need for expensive device components when switching to analog signal forms.
Innovation Solution
Each participant in the fieldbus system is assigned a specific spread spectrum clock signal for transmitting and receiving data signals, using spread spectrum technology to vary the frequency and reduce interference, with a local spread spectrum clock signal being used for synchronous data transmission and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional clock sources are used for fast binary data transmission, then data transmission speed is improved, but electromagnetic interference increases
Solution Approach 1:
The patent applies spread spectrum clock signals that vary their frequency parameters over time, transforming the concentrated high-speed clock signal into a dispersed signal across a wider frequency range. This parameter change allows fast data transmission while reducing peak electromagnetic interference by distributing energy across multiple frequencies rather than concentrating it at a single clock frequency.
2Object-generated harmful factors
If analog signal forms are used to reduce interference, then electromagnetic interference is reduced, but device cost increases
Solution Approach 1:
The patent replaces analog signal forms with digital spread spectrum modulation techniques. Instead of using analog signaling methods that require expensive analog components, the invention uses digital signal processing with spread spectrum coding, maintaining cost-effectiveness while achieving reduced electromagnetic interference through digital domain signal manipulation.
3Reliability
If each participant uses its own local clock oscillator, then synchronization is achieved, but clock signal differences cause transmission issues
Solution Approach 1:
The patent introduces dynamic frequency adjustment where each participant's clock signal is modulated with a unique spread spectrum code. This dynamic approach allows each device to maintain its own clock oscillator while the spread spectrum modulation enables the receiving end to distinguish and synchronize with the correct clock signal despite frequency variations, reducing the need for perfectly matched crystal oscillators.
Data Source
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AI summary
The invention describes a fieldbus system, and in particular a fieldbus device (10), with at least one clocked transmitter (16) and one clocked receiver (17) for sending data signals to and from another fieldbus device (30). To reduce interference emissions, a spread-spectrum clock (40) is provided, which supplies a local spread-spectrum clock signal (SST1). The spread-spectrum clock signal is applied to the transmitter (16) and the receiver (17) to enable the transmission and reception of data signals (DO1, DI1) synchronously with the local spread-spectrum clock signal.