Digital Audio Clock Frequency Shifting for Interference Reduction
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Solution Overview
Problem
Digital audio interfaces in electronic devices generate interference that degrades signal reception in nearby sensitive equipment, such as FM radio receivers and GPS networks, due to electromagnetic leakage, which existing methods like track routing modifications and slew-rate control either increase complexity or compromise signal integrity.
Innovation Solution
A method that modifies the frequency of the transmission clock signal for digital audio data without altering the frame synchronization clock, allowing for a frequency offset that separates the audio signal from interfering frequencies, thereby reducing or eliminating interference without affecting the perceived audio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If track routing modifications are used to reduce interference, then electromagnetic interactions are reduced, but device complexity and surface area increase
Solution Approach 1:
The patent changes the frequency parameter of the digital audio signal by modifying the transmission clock frequency. This frequency shift moves the signal away from sensitive frequency ranges, reducing electromagnetic interference without requiring physical routing modifications or increasing device complexity
2Object-generated harmful factors
If slew-rate control is applied to reduce interference, then electromagnetic leakage is reduced, but signal integrity deteriorates
Solution Approach 1:
Instead of modifying the signal waveform shape through slew-rate control, the patent changes the frequency parameter of the digital audio signal. This approach reduces electromagnetic leakage while preserving the original signal waveform and integrity, avoiding the trade-off inherent in slew-rate control methods
3Object-affected harmful factors
If transmission frequency is shifted to reduce interference, then frequency separation is achieved, but audio perception may be altered
Solution Approach 1:
The patent implements periodic frequency shifting where the transmission clock frequency is modified only during specific time intervals (when digital audio signals are present), while maintaining the original frequency during other intervals. This periodic application allows frequency separation when needed while preserving audio fidelity when the shifted frequency would not affect perception
Solution Approach 2:
The frequency modification is applied locally and selectively - only to the transmission clock during periods when digital audio signals are being transmitted, and only to the extent necessary to achieve frequency separation. The frame synchronization clock remains unchanged, ensuring that audio perception is not altered while still achieving the desired interference reduction
Data Source
AI summary
A method for transmitting and/or receiving a potential aggressor audio signal includes a transmission and/or a reception of successive groups of data timed by a first clock signal within respective successive frames synchronized by a second clock signal. In the presence of a risk of interference of the potential aggressor audio signal with a different, potential victim, signal, during the transmission or reception of the potential aggressor audio signal, the frequency of the first clock signal is modified while keeping the frequency of the second clock signal unchanged.