CDMA Transmitter Orthogonal Codes for Railway Interference
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Solution Overview
Problem
CDMA data transmission systems in severe electromagnetic environments, such as the railway sector, face interference and distortion issues that affect signal quality and data rate, with existing solutions either requiring transmission interruptions or compromising data rate to compensate for noise and distortion.
Innovation Solution
A communication system using online powerline CDMA transmitters with synchronized orthogonal spreading codes, an electromagnetic compatibility control module for amplitude limiting, and a module for determining and correcting the transfer function of the transmission channel in real time, allowing for simultaneous data transmission without interruption and optimizing signal-to-noise ratio and data rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex algorithms with digital filters or FIR impulse response filters are used to compensate for distortion, then distortion compensation is achieved, but device complexity increases and symmetry constraints limit effectiveness
Solution Approach 1:
The patent changes the approach from using complex filters to using parameter-based compensation. By estimating channel parameters (gain, phase, group delay) and applying corrective transformations, the system achieves distortion compensation with simpler processing that avoids the complexity and symmetry constraints of traditional filter-based methods
Solution Approach 2:
The patent replaces the mechanical filter-based distortion compensation system with a parameter estimation and correction system. Instead of using physical digital filters or FIR impulse response filters, the system uses mathematical parameter estimation followed by signal transformation, substituting a more flexible and less constrained approach
2Measurement precision
If transmission interruptions are implemented for exchanging impulse responses to determine gain and group delay, then distortion parameters can be detected, but productivity decreases due to reduced useful flow rate
Solution Approach 1:
The patent implements continuous distortion parameter detection by using pilot signals that are transmitted continuously alongside data signals. This allows the receiver to estimate channel parameters (gain, phase, group delay) without interrupting the useful data transmission, maintaining continuous productivity while achieving accurate measurement
Solution Approach 2:
The patent introduces pilot signals as an intermediary mechanism that enables distortion parameter detection without requiring transmission interruptions. These pilot signals serve as mediators that carry channel information while allowing continuous data transmission to proceed uninterrupted
3Reliability
If noisy transmission channels are eliminated or information is repeated to compensate for noise, then noise compensation is achieved, but data rate decreases
Solution Approach 1:
The patent implements noise compensation through feedback mechanisms where the receiver estimates channel conditions including noise characteristics, and this information is used to adjust transmission parameters. The system uses pilot signals to continuously monitor channel quality and applies adaptive processing to compensate for noise while maintaining data rate
Solution Approach 2:
The patent employs dynamic noise compensation where the system continuously adapts to changing channel conditions. By using pilot signals for real-time channel estimation and applying adaptive equalization and processing, the system maintains optimal performance in varying noise environments without requiring static redundancy or retransmissions that would reduce data rate
Data Source
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AI summary
The invention relates to a communication system (10) comprising at least one CDMA data transmitter (12) and one CDMA data receiver (14), in which the CDMA data transmitter comprises at least one CDMA encoder (18) configured to encode at least each bit of at least two distinct data streams respectively by at least two distinct orthogonal CDMA spreading codes, each representing a data bit, said orthogonal CDMA spreading codes both being known to at least one receiver, and each comprising n elements, the two CDMA spreading codes being configured to be transmitted simultaneously in the same transmission channel to said at least one receiver and to exhibit an amplitude attenuation to each other that is less than a predetermined threshold.