Dynamic Input Level Switching for Low-Noise EVM Measurement
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Solution Overview
Problem
Existing measurement devices face challenges in reducing noise during Error Vector Magnitude (EVM) measurement when the input signal level changes, particularly in low-level sections, due to insufficient noise reduction strategies when the input level is set higher than the signal level.
Innovation Solution
A measurement device with multiple input ports and variable attenuators adjusts the input level dynamically based on the signal section, distributing the signal to different ports and setting appropriate levels for each section to minimize noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the input level is set to a high level to measure high-level signal sections, then the measurement coverage is improved, but the noise increases for low-level signal sections
Solution Approach 1:
The patent applies dynamics by making the input level adjustable and switchable based on the signal section being measured. The measurement device dynamically changes the input level setting: using a higher input level for high-level signal sections and a lower input level for low-level signal sections. This dynamic adjustment allows the device to adapt to different signal conditions, expanding measurement coverage while maintaining low noise levels for each specific measurement context.
2Measurement precision
If the input level is set to a low level to reduce noise, then the measurement precision is improved, but the signal distortion occurs for high-level signal sections
Solution Approach 1:
The patent resolves this contradiction through dynamic adjustment of the input level. When measuring high-level signal sections, the device sets the input level to a higher value to prevent signal distortion and maintain signal integrity. When measuring low-level signal sections, it switches to a lower input level to minimize noise and improve measurement precision. This dynamic switching ensures that the appropriate input level is always used for the current measurement context.
Solution Approach 2:
The patent applies parameter changes by modifying the input level parameter according to the signal section characteristics. The control unit changes the input level parameter from a first value (for high-level sections) to a second value (for low-level sections), optimizing the measurement conditions for each specific case. This parameter adjustment resolves the contradiction between noise reduction and signal integrity preservation.
3Device complexity
If a single input level setting is used for all signal sections, then the device complexity is reduced, but the measurement accuracy deteriorates for varying signal levels
Solution Approach 1:
The patent implements dynamics by introducing a controllable mechanism that adjusts the input level based on the signal section identifier. The control unit receives section information and dynamically selects the appropriate input level setting. While this adds some control complexity, it dramatically improves measurement accuracy for varying signal levels, resolving the contradiction between simplicity and precision.
Solution Approach 2:
The patent applies parameter changes by modifying the input level parameter according to different signal sections. The control unit changes the input level parameter from a first value to a second value based on the section being measured. This parameter adaptation ensures high measurement accuracy across different signal levels while keeping the control logic relatively simple and systematic.
Data Source
AI summary
A measurement device capable of reducing noise during EVM measurement in a case where a level of an input signal changes is provided. A measurement device includes a first input port, a first variable attenuator that attenuates a signal level of an uplink signal input into the first input port in accordance with a set input level, a first AD converter that converts an analog signal attenuated by the first variable attenuator into a digital signal, a signal analysis unit that performs modulation analysis on a section to be measured in the digital signal output from the first AD converter, and a control unit that, in measuring an input signal that consists of a plurality of sections and that has different signal levels in each section, changes the input level in accordance with a section to be measured during measurement of each section.