RF Time Delay Calibration Using Shaped Noise Gating
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Solution Overview
Problem
Time delay-based arrays require periodic recalibration due to aging and environmental changes, but traditional in-situ calibration methods are cumbersome, costly, and impractical for certain systems, especially receive-only arrays, due to the need for additional hardware and potential noise degradation.
Innovation Solution
A time delay calibrator adjusts the gain of RF components using a shaped gate signal, measuring path lengths based on noise data to calibrate the array without injecting a signal into the RF path, allowing for in-situ calibration without additional hardware or noise degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional in-situ calibration injects a signal onto the RF path ahead of the first active component, then calibration accuracy is improved, but device complexity and hardware requirements increase
Solution Approach 1:
The system uses its own internal noise sources and existing RF chain components to perform calibration, eliminating the need for external calibration signal injection hardware. The noise generated by the RF chain itself is modulated by the gate signal to create a calibration reference, allowing the system to calibrate itself without additional external equipment.
Solution Approach 2:
A gate signal is introduced as an intermediary to modulate the noise signal from the RF chain. This gate signal serves as a mediator that allows the calibration process to occur through existing components by creating a time-varying noise pattern that can be correlated to determine time delays, avoiding direct signal injection into the RF path.
2Adaptability or versatility
If traditional in-situ calibration uses additional hardware for signal injection, then calibration capability is improved, but SWaP-C requirements increase
Solution Approach 1:
The RF chain's noise sources and existing components are made multi-functional by using them for both normal operation and calibration purposes. The same RF chain that processes target signals also generates the noise used for calibration, and the same ADC and processing hardware handle both calibration and operational data, eliminating dedicated calibration hardware.
Solution Approach 2:
The system performs calibration using its own internal resources - the RF chain's inherent noise, existing amplifiers, and standard ADC - without requiring additional hardware. This self-service approach reduces SWaP-C by making the calibration function available through components already present in the system.
3Measurement precision
If traditional calibration injects signals into the RF path, then time delay measurement is improved, but noise degradation occurs
Solution Approach 1:
The gate signal acts as an intermediary that modulates the noise rather than directly injecting a calibration signal into the RF path. This indirect approach avoids adding external noise sources while still creating a measurable time-varying pattern in the noise that can be used for precise time delay measurement through correlation techniques.
Solution Approach 2:
The inherent noise from the RF chain, which is typically considered a harmful factor degrading signal quality, is converted into a useful calibration reference. By modulating this noise with the gate signal, the system transforms the noise from an obstacle into a carrier of calibration information that can be extracted through correlation processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and efficient in-situ calibration of time delays in RF paths, reducing SWaP-C requirements and enabling calibration in receive-only arrays without the need for additional hardware, while maintaining phase/time alignment.
Implementation Method 1
The gate voltage generator is configured to generate a shaped gate signal and provide the shaped gate signal to a gate of the active component. The active component is configured to amplify noise with a changing gain based on the shaped gate signal.
Implementation Method 2
The time delay calculator is configured to measure a path length for the RF chain based on an arrival time for the shaped noise data
Data Source
AI summary
A method includes generating a shaped gate signal using a gate voltage generator and providing the shaped gate signal to a gate of an active component of a radio frequency (RF) chain in a time delay-based array. The method also includes amplifying noise with a changing gain based on the shaped gate signal using the active component and generating shaped noise data based on the amplified noise using the RF chain. The method further includes measuring a path length for the RF chain based on an arrival time for the shaped noise data and calculating a time delay for the RF chain based on the path length to calibrate the array.