Integrated Wireless Receiver Using Microsampling for High Dynamic Range
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Solution Overview
Problem
Designing high dynamic range software defined radio (SDR) receivers that can operate over broad bandwidths is challenging due to the near-far problem, high noise figure, and increased complexity, power consumption, and size, especially in network-based wireless location systems where both strong and weak signals need to be detected.
Innovation Solution
The implementation of microsampling techniques, which involve pushing the intermediate frequency (IF) into higher Nyquist zones using a sampling rate several times above the base rate, reducing IF filter loss and allowing for simpler, more integrated receiver designs with low loss SAW filter technology, and employing extreme undersampling to achieve high dynamic range while reducing cost, complexity, and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high dynamic range receivers are designed to operate over broad bandwidths, then the receiver can detect both strong and weak signals simultaneously, but the device complexity and cost increase significantly
Solution Approach 1:
The patent implements dynamic gain control and adjustable filtering stages that can be configured based on the received signal conditions. The receiver can adaptively switch between different gain settings and filter characteristics to optimize performance for either strong or weak signals, resolving the contradiction between broad bandwidth coverage and device complexity by providing dynamic adaptability rather than fixed high-complexity architecture
Solution Approach 2:
The patent changes key operating parameters including gain levels, filtering characteristics, and amplification stages based on signal strength detection. By dynamically adjusting these parameters, the receiver can maintain high dynamic range performance across broad bandwidths without requiring permanently complex hardware configurations for all operating conditions
2Adaptability or versatility
If the receiver bandwidth is increased to detect weak signals, then the dynamic range improves, but the noise figure increases and sensitivity decreases
Solution Approach 1:
The patent divides the broad bandwidth into multiple narrower frequency bands or channels, each processed through separate filtering and amplification stages. This segmentation allows each stage to operate with optimized noise characteristics for its specific bandwidth portion, maintaining sensitivity while achieving overall broad bandwidth coverage through combined processing of multiple segments
Solution Approach 2:
The patent applies different filtering and amplification characteristics to different frequency regions within the broad bandwidth. By tailoring the receiver characteristics locally to each frequency band's requirements, the system maintains optimal sensitivity and low noise figure in each region while collectively covering the entire broad bandwidth spectrum
3Measurement precision
If traditional sampling rates are used, then the Nyquist criterion is satisfied for signal reconstruction, but the ADC complexity and power consumption increase
Solution Approach 1:
The patent applies oversampling followed by decimation, where the ADC samples at a rate higher than the minimum Nyquist requirement, then digital filtering and downsampling reduce the data rate. This partial excessive sampling action provides benefits including improved anti-aliasing performance, better noise shaping, and relaxed timing requirements while the subsequent decimation stage reduces the overall processing burden and power consumption compared to sampling exactly at the Nyquist rate
Solution Approach 2:
The patent implements preliminary analog filtering before the ADC stage to pre-condition the signal and remove out-of-band components. This preliminary action reduces the burden on the ADC by ensuring the input signal already meets the sampling requirements, allowing the use of lower-resolution or lower-speed ADCs that consume less power while maintaining reconstruction accuracy
4Power
If strong signals are received, then the receiver can detect nearby transmitters, but the near-far problem causes masking of weak signals from distant transmitters
Solution Approach 1:
The patent implements dynamic range compression and adaptive gain control that responds to the strength of received signals. When strong signals are detected, the system automatically reduces gain in affected frequency regions or applies compression to prevent saturation and intermodulation products, thereby reducing the near-far effect and allowing weak signals to be detected alongside strong signals without masking
Solution Approach 2:
The patent converts the potentially harmful strong signals into useful information by using them for signal processing reference, interference cancellation, or adaptive filtering training. The strong signals that would normally cause the near-far masking problem are instead utilized to improve the detection of weak signals through techniques such as interference subtraction or adaptive noise cancellation, turning the harmful effect into a benefit
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
This approach enables the design of high dynamic range SDR receivers that maintain full bandwidth coverage with reduced component count, size, and power consumption, effectively addressing the near-far problem and filter loss challenges, while simplifying the signal chain and reducing costs.
Implementation Method 1
allowing for simpler, more integrated receiver designs with low loss SAW filter technology
Data Source
AI summary
Disclosed are methods and systems for filtering an intermediate frequency (IF) band when digitizing a radio frequency (RF) signal using a higher Nyquist zone several times above the sampling rate. Undersampling may be employed along with an undersampled Nyquist filtering technique to implement an integrated receiver for base station applications such as wireless base station beacon monitoring. Such a receiver may be integrated into a smaller package and consume less power at a reduced cost. In one embodiment, the receiver may operate at a high RF sampled frequency that is microsampled in the 10th Nyquist zone at less than 20% undersampling. In another embodiment, the receiver may operate in the 5th Nyquist zone at ½ the sampling rate with 40% undersampling. In various embodiments, sampling and processing functions may be implemented using software on a computer or other embedded computing device.