Inductive Transmitter Noise Immunity via Spread Spectrum and Pulse Code Modulation
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Solution Overview
Problem
Electromagnetic communication systems face challenges in maintaining robustness against noise, especially in the near field region, particularly when operating close to conductive or magnetic structures, where signal absorption is high, and existing techniques like RF transceivers in the far field region are inefficient.
Innovation Solution
A transmitter system incorporating a modulator with a spread spectrum coder and a pulse code modulator, along with a pseudo-noise generator, resonant circuit, and magnetic transducer, which spreads the signal spectrum and encodes it using pulse code modulation, enhancing noise robustness without increasing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high transmitting power is used to compensate for signal absorption in the near field region, then the signal strength is improved, but the energy consumption and device complexity increase
Solution Approach 1:
The patent changes the fundamental parameter of signal transmission from high-power direct transmission to low-power spread spectrum transmission. By spreading the signal energy across a wide frequency band and using pseudo-random coding, the system achieves reliable detection at low power levels through correlation processing at the receiver, resolving the contradiction between reliability and energy consumption
Solution Approach 2:
The patent transitions from single-frequency transmission to multi-frequency spread spectrum transmission. By distributing signal energy across multiple frequency dimensions and using temporal spreading through pseudo-random sequences, the system achieves robust detection without requiring high transmitting power
2Reliability
If spread spectrum encoding is applied to enhance noise robustness, then the noise immunity is improved, but the device complexity increases
Solution Approach 1:
The patent segments the modulation process into two independent stages: spread spectrum encoding followed by pulse code modulation. This segmentation allows each module to perform a specific function with simple structure, avoiding the need for complex integrated solutions while achieving both noise robustness and ease of implementation
Solution Approach 2:
The patent merges spread spectrum encoding with existing pulse code modulation architecture. By integrating the spread spectrum coder as a preprocessing stage before the established PCM modulator, the system leverages proven low-complexity PCM hardware while adding noise robustness through spread spectrum techniques
3Ease of manufacture
If pulse code modulation is used after spread spectrum encoding, then the integration with existing modulators is improved, but the signal processing complexity increases
Solution Approach 1:
The patent segments the signal processing into distinct functional blocks: spread spectrum encoding, pulse code modulation, and resonant circuit modulation. Each block operates independently with well-defined interfaces, simplifying integration with existing modulators while managing processing complexity through modular architecture
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 solution provides a robust and efficient communication system that maintains performance in noisy environments, particularly in the near field region, by spreading the signal across a large frequency band, reducing vulnerability to jamming and absorption, and utilizing a magnetic transducer to leverage the B-field component, which is less affected by conductive materials.
Implementation Method 1
Taking advantage of the oscillation behaviour of a resonant circuit, a data transmission system employs a resonant circuit and switching means adapted to alternatingly energies and de-energies the resonant circuit
Implementation Method 2
utilizing a magnetic transducer to leverage the B-field component, which is less affected by conductive materials
Data Source
Figure 1A~1C
Figure 2
Figure 3A~3D
AI summary
The invention related to a modulator for a communications system. The modulator comprises a spread spectrum coder, a pulse code modulator having a signal input port connectable to a signal output port of the spread spectrum coder. The modulator performs a robust and error free modulation and coding scheme by using a modified spread spectrum scheme combined with pulse code modulation. The communication system contains a low data rate, noise robust modulation and coding scheme using a very simple transmitter. This results in a very straightforward transmitter circuit, reducing size and costs of the transmitter.