Measurement System Correcting Spectral Collapse
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Solution Overview
Problem
Existing measurement systems struggle to accurately measure signals close to the thermal noise floor due to spectral collapse, which leads to unreliable measurements of phase noise or other signal quantities.
Innovation Solution
A measurement system comprising an input port, signal splitter, first and second signal paths, analysis circuit, and control circuit, which splits the input signal into two paths, processes them independently, and then performs conjugate complex multiplication and averaging to determine a corrected averaged power signal by adding an offset to compensate for spectral collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cross correlation techniques are used to suppress noise in signal paths, then noise suppression is improved, but spectral collapse occurs causing measurement accuracy to deteriorate near the thermal noise floor
Solution Approach 1:
The patent applies preliminary action by adding an offset signal to the measured signal before final processing. This offset compensates for the spectral collapse effect in advance, ensuring that measurements near the thermal noise floor remain accurate. The offset is calculated based on the known thermal noise characteristics and is added to prevent the collapse of the noise spectrum.
Solution Approach 2:
The patent changes the parameter of the measured signal by adding an offset that modifies the signal's power spectrum. This parameter change compensates for the spectral collapse by effectively raising the noise floor measurement, allowing accurate measurement of signals close to the thermal noise level without being affected by the collapse phenomenon.
2Measurement precision
If signals are measured close to the thermal noise floor, then sensitivity is improved, but spectral collapse causes the noise to be measured too low reducing reliability
Solution Approach 1:
The patent implements feedback by using knowledge of the thermal noise characteristics and the observed spectral collapse effect to calculate an appropriate offset. This offset is then added to the measured signal, creating a feedback loop that compensates for the measurement error. The system continuously monitors and adjusts for the spectral collapse, ensuring reliable measurements even below the traditional -174 dBm(Hz) threshold.
Solution Approach 2:
The offset signal acts as an intermediary that mediates between the measured signal and the true thermal noise floor. By introducing this intermediate compensation signal, the system bridges the gap caused by spectral collapse, allowing the measurement system to accurately represent the true noise level without being distorted by the collapse effect.
3Measurement precision
If phase noise measurements are conducted, then oscillator characterization is improved, but spectral collapse leads to phase noise being measured too low in some frequency portions
Solution Approach 1:
The patent applies preliminary action by pre-calculating and adding an offset specifically tailored for phase noise measurements. This offset compensates for the spectral collapse effect that would otherwise cause phase noise to be measured too low in certain frequency portions. By applying this correction before final analysis, the complete phase noise spectrum is accurately captured without information loss.
Data Source
AI summary
A measurement system includes an input port, a signal splitter, first and second signal paths, an analysis circuit, and a control circuit. The input port is configured to receive an input signal to be measured. The signal splitter is configured to split the input signal into a first signal that is forwarded to the first signal path and a second signal that is forwarded to the second signal path. The analysis circuit is connected to the first signal path and the second signal path so as to receive both a first processed signal and a second processed signal. The analysis circuit is configured to a complex-valued product signal from the processed signals average the complex-valued product signal over a predetermined number of samples, and determine an averaged power signal based thereon. The control circuit is configured to directly or indirectly add an offset to the averaged power signal.