Digital Bipolarisation Interferometer Sub-Sampling Aliasing Detection

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Solution Overview

Problem

Bipolarization interferometers with undersampled digital reception face challenges in detecting interference situations due to spectral aliasing, which complicates the detection of useful signals and leads to false alarms and poor signal characterization, especially when signals at different frequencies mix in the Nyquist zone.

Innovation Solution

A method that determines interference situations by maximizing the likelihood of measurement vectors using square modules, scalar products, and filtering, allowing for the identification of affected sampling frequencies and eliminating interfered channels to detect useful signals effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If sub-sampling is used to reduce analog-to-digital conversion constraints, then weight/volume/consumption constraints are satisfied, but spectral aliasing causes interference between signals at different frequencies

Engineering Contradiction:

Improvepower consumptionVSAvoidspectral aliasing interference

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful spectral aliasing effect into a useful tool by deliberately designing the sub-sampling frequencies to create controlled aliasing patterns. The interference patterns generated by aliasing are analyzed to detect and characterize the original high-frequency signals, transforming what was previously a detrimental effect into the basis for signal detection and frequency identification

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the sampling frequency parameters to be deliberately lower than the Nyquist frequency, accepting the resulting aliasing. By carefully selecting specific sub-Nyquist sampling rates and analyzing the resulting aliased spectra, the system can identify and characterize original high-frequency signals that would be impossible to detect with conventional sampling at these lower rates

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple signals at different frequencies are received simultaneously, then broadband reception capability is achieved, but aliasing causes signals to mix and become indistinguishable in the Nyquist zone

Engineering Contradiction:

Improvebroadband reception capabilityVSAvoidsignal frequency identification

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the broadband spectrum into multiple aliased zones by using multiple sub-sampling frequencies. Each sampling frequency creates a distinct aliasing pattern that maps different portions of the high-frequency band into the baseband Nyquist zone. By analyzing the distinct aliasing patterns from multiple sampling frequencies, the system can identify and separate signals that would otherwise overlap and become indistinguishable

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces multiple sub-sampling frequencies as intermediary processes that mediate between the high-frequency input signals and the baseband processing system. Each sampling frequency acts as an intermediary that creates a unique aliasing transformation, allowing the system to distinguish between different high-frequency signals through their distinct aliasing signatures in the processed output

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If conventional detection tests are used in sub-sampled receivers, then detection simplicity is maintained, but false alarm rate increases due to undetected parasitic signals

Engineering Contradiction:

Improvedetection test simplicityVSAvoidfalse alarm control

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent implements feedback by using the detected aliasing patterns to inform and adjust the detection process. The system analyzes the spectral characteristics of aliased signals and uses this information to distinguish between genuine target signals and parasitic interference. This feedback mechanism allows the simple detection test to adapt to the presence of parasitic signals, maintaining low false alarm rates while preserving operational simplicity

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3672088B1Digital bi-polarisation interferometer with sub-sampling

Publication Date: 2022.10.19 THALES SA

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AI summary

The present invention relates to a method for identifying interference situations due to spectral aliasing in a broadband digital receiver, the method being implemented by means of an interferometric network, composed of two single-polarization sub-arrays with P broadband antennas, P being an integer greater than or equal to 1, each antenna being followed by an analog receiving chain and one or more digital receiving modules, the number of digital receiving modules being R on each sub-array, distributed identically on the two sub-arrays, the method using assumptions to determine such situations.