Nyquist-Zone Signal Combiner for Low-Loss BER Testing
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Solution Overview
Problem
Conventional signal combining methods in radio receivers, such as power combiners and directional couplers, result in signal power loss and changes to the signal characteristics during bit error rate testing, making the process cumbersome and affecting measurement accuracy.
Innovation Solution
A high-efficiency signal combiner system using a multiplexer, such as a diplexer, in combination with a wideband ADC, allows for the selection and combination of signals from different Nyquist zones in the frequency domain, minimizing signal losses by folding out-of-band noise into the primary signal, thereby maintaining signal power and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power combiner or directional coupler is used to combine signals, then signal combining is achieved, but signal power loss occurs due to conservation of energy
Solution Approach 1:
The patent replaces the mechanical/analog signal combining approach (power combiner or directional coupler) with a digital signal processing approach. By using a wideband ADC to digitize the combined signal and then digitally separating and processing signals from different Nyquist zones, the system avoids the inherent power losses of analog combining components while achieving the same signal combining functionality.
2Adaptability or versatility
If additional components are added for bit error rate testing, then testing capability is improved, but measurement accuracy deteriorates due to changes in signal characteristics
Solution Approach 1:
The patent introduces a wideband ADC as an intermediary component that digitizes the received signal before further processing. This digital intermediary allows for flexible signal manipulation, filtering, and analysis without the need for additional analog components that would alter signal characteristics. The digital domain serves as a neutral intermediary that preserves signal integrity while enabling comprehensive testing capabilities.
3Productivity
If conventional signal combining is used, then signal summation is achieved, but insertion loss increases affecting receiver sensitivity
Solution Approach 1:
The patent exploits the frequency domain dimension by utilizing multiple Nyquist zones. Instead of combining signals in the time domain using power combiners (which incur losses), the system allows signals from different frequency bands (Nyquist zones) to coexist and be processed separately in the digital domain after wideband ADC conversion. This dimensional shift from time-domain combining to frequency-domain processing eliminates insertion losses while maintaining high combining efficiency.
Data Source
AI summary
A high efficiency secondary signal combiner may include a frequency division multiplexer that is configured to receive two or more signals and produce a combined signal. The combined signal may include the two or more signals, and each of the two or more signals may be in different Nyquist zones. The combiner may also include a wideband analog-to-digital converter (ADC) that is configured to frequency shift the combined signal by sub-sampling the two or more signals to produce a sub-sampled signal in a Nyquist zone that is different from the Nyquist zones of the two or more signals.