Beamforming Receiver Spatial Dithering for Higher Dynamic Range
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Solution Overview
Problem
Existing multi-channel digital receiver systems face challenges in achieving high dynamic range while maintaining simplicity and cost-effectiveness, particularly with wideband ADCs, which often suffer from high power consumption and quantization errors, and mono-bit ADCs struggle with low dynamic range and quantization noise.
Innovation Solution
The system incorporates a dithering module with a dither signal generator, multi-channel splitter, and time delay units to add coherent dither signals to each receiving channel, enhancing dynamic range by decorrelating quantization noise and using a digital beam forming unit for null-steering to remove dither signal effects, even with mono-bit ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wideband ADCs with high quantization levels (higher number of bits) are used, then instantaneous dynamic range is improved, but power consumption increases and implementation complexity increases
Solution Approach 1:
The patent segments the dynamic range improvement function across multiple parallel receiver channels, each using low-bit ADCs. By processing multiple channels simultaneously and combining their outputs, the system achieves the equivalent dynamic range of a single high-bit ADC without the associated power consumption and complexity
Solution Approach 2:
Instead of using a single high-resolution ADC, the patent creates multiple copies of low-resolution ADCs across parallel channels. These multiple low-bit converter copies work together through coherent processing to replicate the performance of a single high-bit converter while consuming less power
2Use of energy by moving object
If ADCs with low number of bits are used, then power consumption decreases and implementation becomes simpler, but quantization errors increase causing high level quantization noise
Solution Approach 1:
The patent merges the outputs of multiple low-bit ADCs through coherent processing in the digital beamforming unit. By combining the quantized signals from multiple channels with appropriate weighting and summation, the system recovers the dynamic range information that would be lost in individual low-bit conversions
Solution Approach 2:
The digital beamforming unit acts as an intermediary that processes the quantized outputs from multiple low-bit ADCs. Through digital signal processing operations including multiplication by beamforming weights and summation, it reconstructs the original signal with enhanced dynamic range before passing it to subsequent processing stages
3Measurement precision
If dithering is applied to reduce quantization noise, then dynamic range is improved, but quantization noise is added to the output requiring suppression in post-processing
Solution Approach 1:
The patent converts the harmful quantization noise into a beneficial dither signal that is deliberately added before ADC conversion. This dithered quantization noise, when processed through digital beamforming with null-steering, actually helps separate desired signals from interference while the known dither characteristics enable its subsequent removal
4Measurement precision
If a large number of digital receiver channels are used to form narrow beams, then spatial selectivity is improved, but system complexity increases
Solution Approach 1:
The patent implements dynamic beamforming where the beam pattern and null positions are adaptively adjusted based on signal conditions. The digital beamforming unit dynamically computes weights and applies time delays to achieve spatial selectivity without requiring a fixed large number of physical channels, allowing flexible optimization of the receive pattern
Data Source
AI summary
A system and method for enhancing a dynamic range of a beamforming multi-channel digital receiver are described. The receiver comprises a plurality of receiving channels, each including an analog-to-digital converter configured for converting an analog input signal generated by antenna elements into a digital signal. A “spatial” dither signal is used to decorrelate the quantization noise of the analog-to-digital converters. A dither signal is generated and split into a predetermined number of coherent dithering signals. The method includes providing predetermined time delays to the coherent dithering signals, and adding the delayed coherent dithering signals to the input signals in each receiving channel, correspondingly, thereby creating a dither signal equivalent to a signal arriving from a certain specific direction out-of-field-of-view of the antenna array. Removing of the dither signal based on the direction of arrival, is implemented during beamforming signal processing, thus enhancing the dynamic range of electromagnetic signals arriving within a field-of-view of the antenna array.