Range Profile Digitization Circuit 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 and amplitude resolution, leading to issues with pulse width reduction, switching noise, and capacitive load, which result in unreliable signal capture and inefficient use of transmitted pulses.
Innovation Solution
A range profile digitization circuit that re-uses samplers with multiple decoders and a controller generating regular trigger signals, utilizing a multiphase frequency generator to ensure continuous sampling and reduce capacitive load, while using a differencer and clocked comparators to amplify and quantify signals after sampling, thereby improving signal reliability and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ADCs are used for signal digitization, then amplitude resolution can be maintained, but sampling rate is limited and time resolution deteriorates
Solution Approach 1:
The patent segments the digitization process into two distinct stages: first, a 1-bit comparator performs ultra-fast timing measurement by comparing the signal against a swept threshold (achieving high sampling rate), and second, a counter accumulates the duration of high-level outputs to determine amplitude (achieving high amplitude resolution). This segmentation allows each component to be optimized independently, resolving the contradiction between sampling rate and amplitude resolution.
2Productivity
If multiple parallel samplers are used to increase frame rate, then more range points can be sampled simultaneously, but capacitive load increases and reliability deteriorates
Solution Approach 1:
The patent makes each sampler universal by enabling it to serve multiple decoders through a demultiplexer. A single sampler can sequentially feed its output to different decoders corresponding to different range points, controlled by selector signals. This multi-functionality reduces the total number of samplers needed, thereby reducing capacitive load on the quantizer while maintaining high frame rate capability through parallel processing of multiple range points.
3Measurement precision
If swept-threshold digitization is used to achieve high resolution, then both time and amplitude resolution improve, but switching noise increases and harmful factors worsen
Solution Approach 1:
The patent extracts the quantization function from the sampling path. The 1-bit comparator performs only binary comparison (signal above or below threshold) without full rail-to-rail switching, generating minimal switching noise. The amplitude information is extracted through temporal integration (counting) rather than through high-speed voltage switching, thereby achieving high resolution while minimizing harmful switching noise.
4Speed
If high PRF is used to improve time resolution, then sampling frequency increases, but the number of pulses required for each range point increases and productivity worsens
Solution Approach 1:
The patent implements continuous accumulation of thermometer codes across multiple pulses. Instead of waiting for a complete sweep for each range point before moving to the next, the counter continuously accumulates the high-level output duration from the comparator. This continuous action allows parallel processing of multiple range points simultaneously, maintaining high frame rate while using high PRF for accurate timing measurement.
Data Source
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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.