Correlator for Radio Transmission Frequency Drift

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Solution Overview

Problem

Existing data receivers struggle to detect pilot sequences subject to large time-varying frequency drifts, which occurs due to relative movement between the transmitter and receiver or oscillator mismatches, leading to ineffective signal detection.

Innovation Solution

A data receiver is configured with a detector having a correlator that adjusts a correlation pattern in frequency to compensate for time-varying frequency shifts, allowing detection of pilot sequences even under significant frequency drift.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional detection methods are used for pilot sequences, then detection is simple and straightforward, but detection fails when large time-varying frequency drift occurs

Engineering Contradiction:
Improvedetection reliabilityVSAvoiddetection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by making the correlation pattern adjustable and adaptable to changing frequency conditions. The correlation pattern is dynamically modified based on estimated frequency drift, allowing the detection system to maintain reliability under time-varying frequency conditions rather than using a fixed static pattern

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the correlation pattern parameters (such as timing offsets and frequency adjustments) based on the estimated frequency drift. This allows the detection mechanism to adapt its parameters to compensate for frequency shifts, resolving the contradiction between maintaining simple detection and achieving reliable detection under drift conditions

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the correlation pattern is adjusted in frequency to compensate for time-varying frequency shift, then detection accuracy improves, but the complexity of the detection system increases

Engineering Contradiction:
Improvepilot sequence detection accuracyVSAvoidcorrelator complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies feedback by using the detected frequency drift information to adjust the correlation pattern. The system estimates the frequency shift from the received signal and feeds this information back to modify the correlation pattern, creating a closed-loop system that improves detection accuracy while managing complexity through intelligent adaptation

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent implements preliminary action by pre-calculating and storing multiple correlation patterns that can be selected based on the estimated frequency drift. This allows the system to prepare compensation measures in advance rather than computing complex adjustments in real-time, improving detection accuracy while controlling system complexity

Inventive Principle:
Principle #10Preliminary action

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

The solution enables effective detection of pilot sequences with large time-varying frequency drifts, improving signal reception and data packet detection accuracy.

Implementation Method 1

at least a second pilot sequence of the at least two pilot sequences has a time-varying frequency shift (frequency drift) (e.g., due to a Doppler effect) compared to a first pilot sequence

Methodology Applied
Scientific EffectDoppler effect: Doppler Effect

Data Source

PatentEP4107891B1Packet correlator for a radio transmission system with time-varying frequency drift
Publication Date: 2025.06.11 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP4107891B1 patent drawingFigure 1
  • EP4107891B1 patent drawingFigure 2
  • EP4107891B1 patent drawingFigure 3

AI summary

Embodiments relate to a data receiver, wherein the data receiver is configured to receive a signal from a data transmitter, and the signal has at least two pilot sequences which are distributed in time and optionally in frequency according to a pilot pattern. At least one second pilot sequence of the at least two pilot sequences has a frequency shift which can change over time in contrast to a first pilot sequence of the at least two pilot sequences, and the data receiver has a packet detector with a correlator which is configured to detect the at least two pilot sequences on the basis of a correlation pattern, said correlation pattern being adapted with respect to the frequency in order to reduce the influence of the frequency shift.