RF Measurement Device SNR Feedback for Accuracy
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Solution Overview
Problem
Users of measurement devices, such as vector network analyzers, face challenges in evaluating the quality of measurement data due to lack of insight into the reliability of RF measurements, particularly in the low-frequency region, where non-linearities and unstable calibration can occur, and there is no direct metric to assess measurement accuracy.
Innovation Solution
A measurement device that includes an input terminal, analog-to-digital converter, filter, detector, and controller to calculate the signal-to-noise ratio (SNR) of RF signals, adjusting the intermediate-frequency bandwidth (IFBW) and number of samples to achieve a user-defined SNR, providing a metric for data quality and optimizing measurement settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If constant power and constant IFBW are used in VNA measurements, then the measurement setup is simple, but the measurement accuracy and reliability cannot be assessed
Solution Approach 1:
The system calculates SNR values from measurement data and uses this feedback to assess measurement quality. The controller computes SNR based on the measured signal and noise floor, then uses this information to evaluate whether the measurement meets quality criteria, enabling users to judge measurement reliability without complex setup changes
Solution Approach 2:
The patent introduces SNR as an intermediary metric that bridges the gap between raw measurement data and quality assessment. By calculating and displaying SNR values, the system provides users with a clear indicator of measurement quality without requiring them to understand or configure complex measurement parameters
2Measurement precision
If IFBW is reduced to improve SNR, then measurement accuracy improves, but measurement time increases
Solution Approach 1:
The system dynamically adjusts the IFBW setting based on calculated SNR values and quality criteria. The controller automatically modifies the filter bandwidth during measurements to optimize the balance between measurement speed and quality, rather than using a fixed IFBW setting throughout
Solution Approach 2:
The patent changes the IFBW parameter adaptively based on measurement requirements and SNR calculations. By adjusting this key parameter dynamically, the system optimizes measurement performance across different frequency ranges and signal conditions without manual intervention
3Reliability
If the number of samples is increased to improve measurement quality, then data reliability improves, but productivity decreases
Solution Approach 1:
The system uses SNR calculation as feedback to determine whether additional samples are needed. By continuously monitoring SNR values against quality criteria, the system can stop sampling when sufficient quality is achieved, avoiding unnecessary measurement time extension
4Adaptability or versatility
If UOSM calibration is performed at low frequencies, then coverage is improved, but calibration stability deteriorates due to non-linearities
Solution Approach 1:
The system adjusts measurement parameters such as IFBW and power levels based on frequency and calculated SNR values. This adaptive parameter adjustment compensates for non-linearities at low frequencies and maintains calibration stability across the full frequency range
Data Source
AI summary
A measurement device and method for testing a device under test (DUT). The device includes an input terminal for receiving a RF signal from the DUT; at least one analog-to-digital (A/D) converter configured to generate a digital data including a plurality of sampled signals from the received RF signal; at least one filter configured to filter the digital data generated by the at least one A/D converter based on an intermediate-frequency bandwidth (IFBW) set in the at least one filter; a detector configured to analyse the filtered digital data based on a pre-set number of samples from the filtered digital data; and a controller configured to calculate a signal-to-noise ratio (SNR) value of the analysed filtered digital data, and to adjust at least one of the IFBW of the at least one filter and the number of samples of the detector based on the calculated SNR value.