Vector Signal Analyzer Noise Removal in PSD Measurements
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Solution Overview
Problem
Legacy vector signal analyzers (VSAs) add noise to device under test (DUT) signals, overwhelming parts of the signal and making power spectral density (PSD) measurements inaccurate or impossible, especially for low-power signal components.
Innovation Solution
A method that involves receiving a DUT signal, setting an attenuation value, and applying it to the signal to produce an attenuated signal for the VSA. The method then obtains multiple PSD values, performs an optimization process to remove noise, and calculates the PSD of the device signal by subtracting the noise PSD from the combined PSD values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a legacy vector signal analyzer is used to measure PSD of DUT signal, then the measurement can be performed with existing equipment, but the VSA noise overwhelms parts of the DUT signal making measurements inaccurate
Solution Approach 1:
The patent applies preliminary action by performing multiple PSD measurements at different attenuation settings before conducting the optimization process. The system pre-collects measurement data at various attenuation levels, which are then used in the optimization algorithm to separate DUT signal from VSA noise. This preliminary data collection enables accurate noise removal without requiring real-time complex processing during the actual measurement.
Solution Approach 2:
The patent implements feedback through an optimization process that iteratively adjusts the separation between DUT signal and VSA noise components. The system uses the collected measurement data to continuously refine the estimated DUT signal PSD by comparing against theoretical models and adjusting the separation parameters until optimal results are achieved. This feedback loop ensures accurate removal of VSA noise while preserving the true DUT signal characteristics.
2Object-affected harmful factors
If attenuation is applied to the DUT signal to reduce VSA noise impact, then noise overwhelming is reduced, but the signal power is also reduced requiring multiple measurements
Solution Approach 1:
The patent applies periodic action by performing PSD measurements at multiple discrete attenuation settings rather than using a single continuous setting. The system systematically varies the attenuation through defined steps, collecting measurement data at each level. This periodic sampling approach allows the optimization algorithm to effectively separate signal and noise components while minimizing the total number of measurements required, thus reducing measurement time compared to continuous scanning methods.
Data Source
AI summary
An example method includes the following operations: (i) receiving a device signal from a device under test (DUT); (ii) setting an attenuation value; (iii) applying the attenuation value to the device signal to produce an attenuated device signal for a frequency spectrum analyzing device, where the frequency spectrum analyzing device produces a noise signal; (iv) obtaining a power spectral density value using the frequency spectrum analyzing device, where a power spectral density comprises a power, at a frequency value, of a combined signal that is based on the attenuated device signal and the noise signal; (v) repeating operations (ii), (iii), and (iv) one or more times to produce multiple power spectral density values; (vi) repeating operations (i), (ii), (iii), (iv), and (v) one or more times to add power spectral density values to the multiple power spectral density values; and (vii) obtaining a power spectral density of the device signal.