Receiver Range Profile Digitization with Reused Samplers and Decoders
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Solution Overview
Problem
Existing impulse radar receiver architectures face challenges in achieving high-speed range profile digitization due to limitations in sampling rate, amplitude resolution, and switching noise, particularly with traditional ADCs and swept-threshold systems, which result in unreliable signal capture and inefficient pulse usage.
Innovation Solution
A range profile digitization circuit that employs a signal quantizer, multiple samplers, decoders, and a demultiplexer to re-use samplers, along with a controller for generating trigger signals, allowing for efficient parallel sampling and reduced capacitive load, and uses a differencer with clocked comparators to avoid early signal quantization and minimize switching noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ADCs are used for signal digitization, then amplitude resolution can be achieved, but sampling rate is limited and time resolution deteriorates
Solution Approach 1:
The patent segments the signal processing function into two distinct components: a 1-bit comparator that provides high-speed time resolution and a counter that accumulates multiple comparator outputs to achieve high-bit amplitude resolution. This segmentation allows each component to optimize for its specific function without the trade-off present in traditional ADCs.
Solution Approach 2:
The patent employs periodic sweeping of the threshold voltage through multiple pulses to build up the thermometer code. By periodically varying the threshold and accumulating results over multiple pulse repetitions, the system achieves high amplitude resolution while maintaining high sampling rates through the fast 1-bit comparator.
2Productivity
If multiple parallel counters are used to sample multiple range points simultaneously, then productivity increases, but device complexity increases due to multiple samplers and triggers
Solution Approach 1:
The patent makes the 1-bit comparator universal by having it serve multiple range points sequentially through threshold sweeping. A single comparator instance processes multiple range bins by varying its threshold voltage over time, eliminating the need for separate comparators for each range point and reducing overall system complexity.
Solution Approach 2:
The patent merges the functions of multiple comparators into a single comparator that operates sequentially across different range points. By combining these functions and using a single counter to accumulate results for all range bins, the system achieves parallel processing capability without the complexity of multiple independent sampling chains.
3Measurement precision
If early signal quantization is performed to achieve high time resolution, then switching noise increases and signal reliability deteriorates
Solution Approach 1:
The patent uses a 1-bit comparator that operates in a simplified, low-complexity manner to perform rapid quantization. This 'cheap' quantization approach accepts some noise but achieves the critical time resolution function, while the subsequent counter integration averages out the noise over multiple pulses, effectively separating the time-resolution function from the noise-problematic high-resolution quantization.
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 solution enables high-speed, reliable range profile digitization with improved time and amplitude resolution, reduced switching noise, and efficient pulse usage, allowing for more accurate and continuous sampling of range profiles.
Implementation Method 1
a comparator arranged to receive the received signal and a threshold signal and output a binary value based on a comparison of the received signal with the threshold signal
Implementation Method 2
a sampler arranged to sample and hold the quantized signal upon receipt of a trigger signal
Implementation Method 3
a decoder arranged to decode the sampled and held signal to produce a digital value
Data Source
Figure 1a~1c
Figure 2~3
Figure 4~5
AI summary
A range profile digitization circuit for converting a repeating analog input signal into a time series of digital amplitude values, the converter comprising: a signal quantizer arranged to receive the analog input signal and a threshold input and arranged to output a binary value quantized output signal based on a comparison of the input signal with the threshold signal; a plurality of samplers each arranged to sample and hold its input signal upon receipt of a trigger signal; and for each sampler: a plurality of decoders and a demultiplexer arranged to receive an output from the sampler and pass it to a selected one of said decoders based on a selector input. With a plurality of decoders associated with each of the samplers, each sampler can be re-used during the building up of the range profile. To build up the range profile of the signal a decoder is required for each range point in order to convert the thermometer coded input into a digital value. Decoder values may be generated by storing and accumulating the individual bits of the thermometer coded input over multiple pulse transmissions, each bit resulting from a comparison against a threshold value in the swept threshold system. The decoder values provide the amplitude resolution. Counters are one convenient form of decoder.