TSB-SDR Decimation Filter for Narrow Band Filtering
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Solution Overview
Problem
Current Software Defined Radio (SDR) systems lack full flexibility and efficiency due to complex analog front-end and back-end blocks, which are required for different modulation techniques and wireless standards, leading to difficulties in achieving effective narrow band filtering and maintaining orthogonality between I and Q channels.
Innovation Solution
The implementation of Periodic Time Segment Sequence Based Decimation (PTSSBD) as a discrete time decimation filter, allowing for reconfigurable narrow band filtering across any band, using a Time Segment Based Software Defined Radio (TSB-SDR) system that breaks down modulated signals into time segments for processing, enabling flexible reception and transmission across various modulation schemes and standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If customized analog front-end and back-end blocks are used for different modulation techniques and wireless standards, then the system can accommodate various modulation schemes and standards, but the device complexity increases significantly
Solution Approach 1:
The patent implements a universal software-defined radio architecture where a single reconfigurable analog front-end and back-end can support multiple modulation techniques (QPSK, QAM, OFDM, CDMA) and wireless standards through software control. The analog components are designed with adjustable parameters that can be reconfigured via digital signal processing, eliminating the need for separate customized hardware blocks for each standard.
Solution Approach 2:
The system changes operational parameters dynamically to adapt to different modulation schemes. The analog front-end includes adjustable filters, gain stages, and frequency converters whose characteristics can be modified through digital control. The back-end similarly adjusts its parameters based on the desired modulation technique, allowing one hardware platform to support multiple standards without physical reconfiguration.
2Reliability
If IF stages are used to process modulated signals, then signal processing can be performed, but spurs and image frequency artifacts are generated
Solution Approach 1:
The patent extracts and removes the harmful spurs and image frequency artifacts generated by IF stages through digital signal processing. After the analog IF processing, a digital filter bank is applied to selectively eliminate the unwanted frequency components while preserving the desired signal. This separation of analog processing and digital cleanup allows the system to benefit from IF stage functionality while removing its detrimental effects.
Solution Approach 2:
The patent introduces digital signal processing as an intermediary between the analog IF stages and the final baseband output. This digital intermediary layer processes the IF signal, removes artifacts, and converts it to baseband, acting as a bridge that eliminates the harmful effects of analog processing while maintaining signal integrity.
3Adaptability or versatility
If quadrature modulation is used to achieve flexible communication, then various modulation techniques can be implemented, but I/Q channel mismatches and orthogonality issues increase complexity
Solution Approach 1:
The patent implements feedback mechanisms that continuously monitor the I/Q channel orthogonality and automatically adjust the analog front-end parameters to maintain proper quadrature relationships. Digital signal processing algorithms detect I/Q mismatches and generate correction signals that are fed back to the analog mixers and filters, dynamically compensating for drift and mismatches without requiring complex manual calibration.
4Device complexity
If conventional zero IF approaches are used to simplify IF complexities, then the system structure is simplified, but I/Q mismatch and orthogonality issues are compounded and noise performance degrades
Solution Approach 1:
The patent segments the signal processing into distinct analog and digital stages. Rather than attempting to handle all processing in a single zero-IF stage, the system performs initial frequency conversion and filtering in the analog domain, then completes the conversion to baseband in the digital domain. This segmentation allows each stage to be optimized for its specific function, maintaining noise performance while achieving structural simplicity.
Data Source
AI summary
An input signal having at least one modulated signal is captured. At least four analog sample streams are generated from the input signal. Each analog sample stream is generated by sampling the input signal at a frequency substantially equal to the frequency at which each other analog sample stream is generated and at a phase separate from that at which each other analog sample stream is generated. For each analog sample stream, multiple analog samples of the analog sample stream are combined to create a bandwidth adjusted signal. The bandwidth adjusted signals are jointly representative of the input signal.