Signal Detection Circuit Using Segmented Correlators for Low Signal Synchronization
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Solution Overview
Problem
Spectrum spreading receivers face challenges in maintaining synchronization detection reliability, particularly at low signal levels due to noise interference, leading to delayed synchronization and potential failure in generating reception data and clock in wireless communication systems.
Innovation Solution
A signal detection circuit with a correlation circuit comprising multiple correlators that compute correlation values and generate additional values through adders, with a subtractor comparing these values to a threshold for synchronization detection, ensuring reliable synchronization irrespective of signal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single correlator is used for synchronization detection, then the device complexity is low, but the reliability of synchronization detection deteriorates at low signal levels due to noise interference
Solution Approach 1:
The patent divides the correlation computation into multiple stages by using multiple correlators (first correlator, second correlator, third correlator) that process the received signal at different times. Each correlator computes correlation values for specific portions of the spreading sequence, and these values are accumulated to produce the final synchronization detection result. This segmentation allows the system to achieve higher reliability through diversified computation while managing complexity through structured organization.
Solution Approach 2:
The patent performs preliminary correlation computations in advance using multiple correlators that operate in parallel or sequential stages before the final synchronization detection. The first correlator computes correlation values for initial portions of the signal, which are then used by subsequent correlators. This preliminary action ensures that sufficient correlation data is gathered before the final decision, improving detection reliability especially at low signal levels.
2Measurement precision
If the threshold value for correlation is set high to ensure accuracy, then the measurement precision is improved, but the synchronization detection timing is delayed
Solution Approach 1:
The patent performs preliminary correlation computations using multiple correlators that accumulate correlation values in advance. The first correlator computes initial correlation values, which are then used by the second and third correlators to compute additional correlation values. This accumulated result is compared against the threshold, allowing the system to reach synchronization detection faster while maintaining precision through the cumulative effect of multiple correlation computations.
Solution Approach 2:
The patent dynamically adjusts the correlation computation process by using multiple correlators that can operate at different rates or stages. The system adapts the correlation value accumulation process to achieve both speed and precision, allowing the synchronization detection to occur at optimal timing rather than being fixed by a single high-threshold comparison.
3Reliability
If multiple correlators are used to improve synchronization detection reliability, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent segments the correlation computation task into multiple correlators, each responsible for specific portions of the spreading sequence. The first correlator handles initial portions, the second correlator handles intermediate portions, and the third correlator handles final portions. This segmentation allows the system to achieve high reliability through distributed computation while managing complexity through clear functional division and structured data flow.
Solution Approach 2:
The patent merges the output of multiple correlators by accumulating their correlation values through an adder circuit. The correlation values from the first, second, and third correlators are combined to produce a total correlation value that is then compared against the threshold. This merging approach allows the system to achieve higher reliability through combined evidence from multiple correlators while using efficient accumulation logic to manage the added complexity.
Data Source
AI summary
A signal detection circuit includes: a correlation circuit including the first through nth correlators connected sequentially as the first through nth stage correlators and each computing a correlation value between a received signal and a spreading sequence while shifting the received signal to the next stage depending on the chip rate period of the spreading sequence; a first adder that adds k correlation values computed by k correlators so as to generate a first addition value; a second adder that adds r correlation values computed by r correlators so as to generate a second addition value; a subtractor that subtracts the first addition value from the second addition value so as to generate a subtraction value; and a synchronization detection unit that compares the subtraction value with a threshold value, so as to detect the synchronization timing of the spreading sequence and the received signal.