Multi-Level Beacon Tone Modulation for Optical Data Signals

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Solution Overview

Problem

In free space optical communication systems, single-level modulation of optical data signals with beacon tones leads to decreased data receiver sensitivity due to varying bit-to-bit 'swing' and difficulty in filtering out the beacon tone, limiting the usefulness of the data signal.

Innovation Solution

Implementing multi-level modulation, where both the high and low levels of the data signal are modulated with different beacon tones, with the second level modulated in phase with the first, allowing for better utilization of optical power dynamic range and improved filtering capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If single-level modulation with beacon tone is used, then mechanical alignment is enabled, but data receiver sensitivity decreases and beacon tone filtering becomes difficult

Engineering Contradiction:

Improvedata receiver sensitivityVSAvoidmodulation technique complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the modulation process by applying different beacon tone modulations to different data signal levels. Specifically, the high level of the data signal is modulated with a first beacon tone while the low level is modulated with a second beacon tone, allowing separate processing and filtering of each level's beacon component.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by using different beacon tone characteristics for different parts of the data signal. The first beacon tone for the high level and the second beacon tone for the low level have different properties, enabling targeted filtering and processing for each signal level to improve overall receiver sensitivity.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If beacon tone is modulated on data signal, then mechanical alignment is achieved, but beacon tone cannot be easily filtered out

Engineering Contradiction:

Improvebeacon tone filteringVSAvoiddata signal usefulness

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent segments the beacon tone into two distinct components: a first beacon tone modulated on the high data level and a second beacon tone modulated on the low data level. This segmentation allows the receiver to filter out each beacon tone component separately, making the filtering process more effective and preserving the usefulness of the data signal.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using a single beacon tone that contaminates the entire data signal, the patent inverts the approach by using different beacon tones for different signal levels. This inversion allows the beacon functionality to be maintained while enabling effective separation and filtering of the beacon components from the data signal.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If multi-level modulation with different beacon tones is used, then beacon tone filtering is improved, but system complexity increases

Engineering Contradiction:

Improvebeacon tone filteringVSAvoidmodulator complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The modulator is segmented into multiple processing paths, with each path handling a specific data signal level and its corresponding beacon tone. This segmentation allows independent optimization of each modulation path while maintaining overall system functionality, making the increased complexity manageable and beneficial.

Inventive Principle:

Principle #1Segmentation

4Reliability

If single-level modulation is used, then system simplicity is maintained, but bit-to-bit swing varies causing sensitivity loss

Engineering Contradiction:

Improvedata receiver sensitivityVSAvoidbit-to-bit swing consistency

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent segments the data signal into multiple levels (high and low), each modulated with appropriate beacon tones. This segmentation stabilizes the bit-to-bit swing by ensuring consistent modulation characteristics across different signal levels, thereby improving data receiver sensitivity through more predictable signal behavior.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10367585B2Methods and systems for multi-level beacon tone modulation of an optical data signal

Publication Date: 2019.07.30 CACI LGS INNOVATIONS LLC

AI summary

Methods for systems are described for communicating an optical data signal. An example method may comprise receiving a data signal comprising a first level indicative of an upper end of a power range of the data signal and a second level indicative of a lower end of the power range of the data signal. The example method may comprise modulating the data signal to generate a modulated data signal. The modulated data signal may comprise the first level modulated with a first beacon tone and the second level modulated with a second beacon tone. The second level may be modulated in phase with the first level. The method may comprise transmitting an optical signal comprising the modulated data signal.