Signal Detection With Indexed Filtering for Optical Fiber Measurement
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Solution Overview
Problem
Conventional lock-in amplifiers fail to separate and detect amplitudes of time-divisional signals whose amplitudes change over time, as they can only process a single output from low pass filtering, preventing the detection of multiple amplitude levels in signals like Brillouin scattering light in optical fibers.
Innovation Solution
A signal detecting device with a multiplier, filter processor, and storage units that utilize an index signal to separate and store filtering results based on amplitude changes, allowing for the detection of multiple amplitudes by switching internal states and storage areas according to the index signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional lock-in amplifier uses a single low pass filter to extract DC component from multiplied signal, then the device structure remains simple, but it cannot separate and detect multiple amplitude levels of time-divisional signals
Solution Approach 1:
The patent divides the filter processing into multiple independent low pass filters (first, second, third, fourth filters) corresponding to different time division periods. Each filter processes signals from specific periods and stores results in separate storage units, enabling parallel detection of multiple amplitude levels without signal interference.
Solution Approach 2:
The patent introduces a time dimension by associating different filters and storage units with specific time division periods (first period, second period, third period, fourth period). This temporal dimensionality allows the system to distinguish and process multiple amplitude levels that would otherwise be indistinguishable in a single continuous signal stream.
2Measurement precision
If a conventional lock-in amplifier processes only a single output from low pass filtering, then the processing logic remains simple, but it prevents detection of multiple amplitude changes in time-divisional signals
Solution Approach 1:
The patent segments the storage function into multiple independent storage units (first storage unit, second storage unit, third storage unit, fourth storage unit), each dedicated to storing amplitude information from a specific time period. This segmentation allows simultaneous preservation of multiple amplitude levels without data overwriting or loss.
Solution Approach 2:
The patent creates a universal processing framework where multiple identical filter-storage pairs can handle different time periods with the same processing logic. Each low pass filter and its corresponding storage unit form a universal module that can be replicated and configured for specific time periods, enabling scalable detection of any number of time-divisional signal amplitudes.
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A signal detecting device (1; 2) includes a multiplier (13) configured to multiply a measurement signal (MS) by a reference signal (RS), a filter (16) configured to filter a multiplication result from the multiplier (13), a first storage (17) configured to store an internal state of the filter (16), and a second storage (18) configured to store a filtering result from the filter processor (16). The filter (16) is configured to filter the multiplication result using the internal state stored in the first storage (17). The first storage (17) is configured to switch an area in or from which the filter (16) writes or reads the internal state in accordance with an index signal (IS) representing a type of amplitude of a time-divisional signal (DS) in the measurement signal (MS). The second storage (18) is configured to switch of an area in which the filtering result is stored in accordance with the index signal (IS).