Block-Based Signal Down-Conversion With Phase-Preserving Mixing
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Solution Overview
Problem
The existing methods for down-converting sampled signals are resource-intensive and can result in phase information loss, particularly when demodulating phase-encoded data or determining the time of arrival with high resolution.
Innovation Solution
A method involving a mixing-and-combining operation applied to successive sub-sequences of input samples, using a periodic mixing signal to generate output samples at a lower rate, which preserves phase information through phase-correction operations if necessary, and can be implemented efficiently with hardware optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If traditional digital down-conversion is used with continuous mixing operation, then phase information is preserved, but processing resource consumption increases significantly
Solution Approach 1:
The patent applies periodic action by using a periodic mixing signal (cosine and sine waves) that is applied repeatedly to successive blocks of input samples. Instead of continuous mixing, the mixing operation is performed in periodic blocks, where each block is mixed with the periodic signal and then down-sampled. This periodic block-based approach reduces processing resource consumption while maintaining phase information through the structured repetition of the mixing operation.
Solution Approach 2:
The patent segments the continuous signal processing into discrete blocks of input samples. Each block is processed independently through the mixing-and-combining operation, which divides the continuous mixing task into manageable segments. This segmentation allows for efficient processing with reduced computational resources while preserving phase information through the structured block-based approach.
2Speed
If down-sampling is performed after continuous mixing, then output rate is reduced, but processing complexity increases
Solution Approach 1:
The patent merges the mixing operation and down-sampling into a single integrated mixing-and-combining operation. Instead of performing continuous mixing followed by separate down-sampling, the method combines these operations by applying the periodic mixing signal and simultaneously performing the down-sampling through selective combination of mixed samples. This merging reduces processing complexity while achieving the desired output rate reduction.
3Productivity
If block-based mixing is used to reduce processing load, then processing efficiency improves, but phase information may be lost
Solution Approach 1:
The patent implements feedback through the periodic application of mixing signals across successive blocks and the combining operation that integrates results from multiple blocks. The periodic structure provides a feedback mechanism that maintains phase coherence across block boundaries, ensuring that phase information is preserved while benefiting from the processing efficiency of block-based operations.
Solution Approach 2:
The patent applies preliminary action by pre-defining the periodic mixing signal pattern before processing the input blocks. The cosine and sine mixing signals are prepared in advance with known periodic characteristics, allowing the block-based processing to maintain phase information through this pre-established framework. This preliminary setup enables efficient block processing without sacrificing phase accuracy.
Data Source
AI summary
An apparatus (7) for down-converting a sampled signal comprises a processing system (206) configured to apply a mixing-and-combining operation repeatedly to successive sub-sequences of N input samples, X, representative of a signal and having an initial sampling rate, M, to generate a sequence of output samples, Y, having an output rate, T, lower than the initial sampling rate M. The sub-sequences of the N input samples, X, are spaced at intervals that correspond to the output rate M. The mixing-and-combining operation generates a respective output sample Y from each sub-sequence, where Y depends on a set of products of the input samples X of the sub-sequence with respective values derived from a periodic mixing signal having a mixing frequency.