Adaptive Leakage Cancellation in Simultaneous Transmit Receive RF Systems
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Solution Overview
Problem
Current techniques for leakage signal cancellation in simultaneous transmit and receive RF systems suffer from significant delays and distortion due to analog feedback, which limits cancellation effectiveness and is not adaptive to dynamic signals or environments, leading to inaccurate readings and 'blind spots' in radar applications.
Innovation Solution
A digital system utilizing a super sampled adaptive finite input response (FIR) filter with a frequency domain adaptive filter (FDAF) to calculate filter coefficients in real-time, allowing for real-time generation and application of a cancellation signal to eliminate leakage, thereby minimizing latency and improving signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If analog feedback is used for leakage cancellation, then the cancellation signal can be generated, but additional distortion is added to the cancellation signal and significant delays occur, limiting cancellation effectiveness
Solution Approach 1:
The patent replaces the analog feedback mechanism with a digital signal processing approach. A digital receiver generates a cancellation signal by processing the received signal through digital filters and algorithms, then subtracts this digital cancellation signal from the received signal. This substitution eliminates the distortion and delays inherent in analog feedback systems while maintaining the leakage cancellation function.
Solution Approach 2:
The patent introduces a digital signal processor as an intermediary between the received signal and the cancellation process. The digital processor computes filter coefficients and generates cancellation signals through mathematical operations, acting as a mediator that avoids the direct analog feedback path and its associated problems of distortion and delay.
2Object-generated harmful factors
If adaptive filtering is performed with real-time coefficient calculation, then cancellation effectiveness improves, but system complexity and computational requirements increase
Solution Approach 1:
The patent performs preliminary computation of filter coefficients using recorded or previously available transmit and received signals. By calculating coefficients in advance or using historical data, the system reduces real-time computational burden while maintaining adaptive cancellation effectiveness. This preliminary action allows the complex adaptive filtering to be done when computational resources are more readily available.
Solution Approach 2:
The patent uses copies of previously recorded transmit and received signals to compute filter coefficients. Instead of requiring continuous real-time processing of live signals, the system can use stored signal copies for coefficient calculation, reducing the complexity and computational requirements of the real-time system while maintaining adaptive cancellation performance.
3Device complexity
If offline computation of coefficients is used, then system complexity is reduced, but the system is not adaptive to dynamic signals or environments
Solution Approach 1:
The patent implements a hybrid approach where the system can operate in both static and dynamic modes. Filter coefficients can be computed offline for static conditions, and the system can adaptively update coefficients when dynamic conditions are detected. This dynamic operation mode allows the system to maintain low complexity during stable conditions while adapting to changing environments when necessary.
Solution Approach 2:
The patent employs periodic updates of filter coefficients rather than continuous real-time computation. The system can recalculate coefficients at scheduled intervals or when triggered by specific conditions, combining the benefits of offline computation with periodic adaptation. This periodic action maintains adaptability to dynamic signals while keeping overall system complexity manageable through intermittent rather than continuous processing.
Data Source
AI summary
Method and apparatus for leakage signal cancellation in a simultaneous transmit and receive RF system includes: generating a digital transmit signal for transmission from the system; receiving a receive signal produced by reflection of the transmit signal from an object or generated by a second RF system; adaptively filtering the transmit signal by an adaptive finite input response (FIR) filter; calculating filter coefficients for the adaptive FIR filter in real-time at a different sampling rate; adaptively inputting the calculated filter coefficients to the adaptive FIR filter to generate a cancellation signal in real-time; and applying the cancellation signal to the receive signal to cancel leakage in the receive signal to generate an optimum receive signal.