Variable Impedance Matching Using a Single Digital Feedback Loop
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Solution Overview
Problem
Conventional transmission apparatuses for speech coding/decoding units have high circuit complexity and cost due to the need for two digital feedback loops and recursive filter units, which operate at high sampling rates and are less flexible than non-recursive units.
Innovation Solution
A simplified digital feedback arrangement with a single digital feedback loop, utilizing a feedback filter device with both recursive and non-recursive filter units, allowing operation at a lower signal rate and reducing circuit complexity by combining low-order recursive and high-order non-recursive filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two digital feedback loops are used for impedance matching, then accurate impedance control is achieved, but circuit complexity and cost increase significantly
Solution Approach 1:
The patent combines the functions of two separate digital feedback loops into a single digital feedback loop. The first feedback loop (DS1) that previously operated at high sampling rate for coarse impedance matching is merged with the second feedback loop (DS2) that operated at lower sampling rate for fine impedance matching. This consolidation reduces the number of feedback paths and associated circuitry while maintaining impedance matching accuracy through coordinated operation of the analog feedback device and the single digital feedback loop.
Solution Approach 2:
The patent implements dynamic sampling rate adjustment where the single digital feedback loop can operate at different sampling rates depending on the impedance matching requirements. The feedback filter device dynamically selects between recursive filter units (for lower sampling rates) and non-recursive filter units (for higher sampling rates), allowing the system to adapt its operation to maintain accuracy while reducing overall complexity and power consumption.
2Ease of manufacture
If recursive filter units are used in digital feedback loops, then flexibility is reduced, but implementation is simpler
Solution Approach 1:
The patent designs the feedback filter device to perform multiple functions through a unified structure that can operate in different modes. The filter device can switch between recursive and non-recursive filter unit configurations, allowing it to adapt to different impedance matching scenarios. This multi-functionality enables the same hardware structure to provide both the simplicity of recursive filters and the flexibility of non-recursive filters when needed.
Solution Approach 2:
The patent employs a composite filter structure that combines both recursive and non-recursive filter units within the same feedback path. This composite approach allows the system to leverage the advantages of both filter types - the computational efficiency and simplicity of recursive filters and the flexibility and stability of non-recursive filters - by selectively engaging appropriate filter units based on the specific impedance matching requirements.
3Measurement precision
If digital feedback loops operate at high sampling rates, then impedance matching precision is maintained, but power consumption and complexity increase
Solution Approach 1:
The patent implements periodic sampling rate adjustment where the digital feedback loop operates at high sampling rates only when necessary for precise impedance matching, and switches to lower sampling rates during normal operation. The feedback filter device periodically evaluates the impedance matching requirements and dynamically adjusts the sampling rate, maintaining precision when needed while reducing power consumption during stable operating conditions.
Data Source
AI summary
The invention provides a transmission apparatus (100) for transmission of electrical signals between a line driver (205), which is connected to a transmission line (201), and a switching center (301), having an analog feedback device (101) for coarse setting of a line voltage level (210) on the transmission line (201), and a digital feedback device (102), which is coupled to the analog feedback device (101) and has a feedback filter device (118), designed such that a filter input signal (404) can be converted to a filter output signal (405) at a rate which is lower than the sampling rate (fa) of an analog/digital converter (104).