Dual-Conversion Frequency Converter for Spurious-Free Satellite Repeaters

Solution Overview

Problem

Satellite-based repeater systems lack flexibility in frequency adjustment, leading to signal degradation and increased costs due to the need for multiple frequency converters and complex switching networks, which are limited by the generation of unwanted spurious signals from fixed local oscillator frequencies.

Innovation Solution

A method employing dual frequency conversion stages with local oscillator signals where the first and second local oscillator frequencies are higher than the uplink signal, allowing for arbitrary frequency adjustment without generating spurious signals within the operating bandwidth, using a combination of fixed and programmable phase-locked loops to generate local oscillator signals with correlated phase noise for cancellation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a large number of frequency converters with unique local oscillator frequencies are used to increase flexibility, then the ability to adapt to new traffic and frequency changes is improved, but the number of frequency converters increases and signal losses increase

Engineering Contradiction:

Improvefrequency adaptabilityVSAvoidsignal loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

A single frequency converter is designed to perform multiple frequency conversion tasks by using a synthesized local oscillator that can be programmed to different frequencies. The converter can handle both uplink-to-intermediate and intermediate-to-downlink conversions, replacing the need for multiple dedicated converters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The local oscillator frequency is made dynamically adjustable through a synthesized oscillator system controlled by a processor. This allows the frequency to be changed arbitrarily to adapt to different traffic requirements and frequency allocations without hardware changes.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If a synthesized local oscillator is used to enable arbitrary frequency changes, then frequency flexibility is improved, but unwanted spurious output signals are generated that degrade system performance

Engineering Contradiction:

Improvefrequency flexibilityVSAvoidspurious signals

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The spurious signals generated by the synthesized local oscillator are converted into a manageable problem by using a dual-conversion architecture. The first conversion stage produces spurious signals at frequencies that are subsequently filtered out in the second conversion stage, transforming the harmful spurious outputs into removable intermediate frequency artifacts.

Inventive Principle:

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

Solution Approach 2:

The frequency conversion process is segmented into two separate stages. The first stage converts the uplink frequency to an intermediate frequency, and the second stage converts the intermediate frequency to the downlink frequency. This segmentation allows spurious signals from the first stage to be filtered before the second stage processing.

Inventive Principle:

Principle #1Segmentation

3Reliability

If multiple frequency converters are used to avoid spurious signals, then signal quality is improved, but the system complexity and equipment cost increase

Engineering Contradiction:

Improvesignal qualityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A single frequency converter is designed to perform multiple frequency conversion tasks by using a synthesized local oscillator that can be programmed to different frequencies. The converter can handle both uplink-to-intermediate and intermediate-to-downlink conversions, replacing the need for multiple dedicated converters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The frequency conversion process is segmented into two separate stages. The first stage converts the uplink frequency to an intermediate frequency, and the second stage converts the intermediate frequency to the downlink frequency. This segmentation allows spurious signals from the first stage to be filtered before the second stage processing.

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If switching networks are used to address different frequency converters, then frequency adaptability is improved, but signal losses increase and noise contribution increases

Engineering Contradiction:

Improvefrequency adaptabilityVSAvoidnoise contribution

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

A single frequency converter is designed to perform multiple frequency conversion tasks by using a synthesized local oscillator that can be programmed to different frequencies. The converter can handle both uplink-to-intermediate and intermediate-to-downlink conversions, replacing the need for multiple dedicated converters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses a processor to control the synthesized local oscillator frequency based on required frequency conversions. The processor receives input about the desired frequency changes and adjusts the oscillator accordingly, creating a closed-loop control system that adapts to different operational requirements.

Inventive Principle:

Principle #23Feedback

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

This approach enables flexible frequency adjustment in satellite repeater systems without signal degradation, reduces equipment redundancy, and minimizes signal losses by integrating multiplexing functions within the frequency converter, ensuring spurious-free performance and improved linearity.

Implementation Method 1

mixing said uplink signal with said first local oscillator signal to generate an intermediate signal having a frequency fMF; at a second frequency conversion stage, mixing said intermediate signal with said at least second local oscillator signal to generate a downlink signal

Methodology Applied

Scientific EffectFrequency mixing: Heterodyne

Implementation Method 2

a low phase-noise phase lock loop (PLL)... said oscillators being phase and frequency locked to a suitable frequency

Methodology Applied

Scientific EffectPhase locking:

Data Source

PatentEP2007030B1Spurious-free flexible frequency converter and a satellite communication repeater architecture

Publication Date: 2012.04.04 RUAG SPACE

Figure 1~2
Figure 3

AI summary

A method for frequency conversion within a satellite-based repeater system, comprising the steps of receiving an uplink radio frequency signal (RF) having a frequency fRF, generating a first (LO1) and at least a second (L02) local oscillator signal having frequencies fLO1 and fLO2, respectively, mixing at a first frequency conversion stage said uplink signal (RF) with said first local oscillator signal (LO1) to generate an intermediate signal (MF) having a frequency fMF, and, at a second frequency conversion stage, mixing said intermediate signal (MF) with said at least second local oscillator signal (LO2) to generate a downlink signal (IF) having a frequency fIF, wherein the generation and mixing of said signals (LO1, LO2, RF, MF) are performed such that: fLO⁢1⁢and fLO⁢2>fRF⁢and fIF fMF⁢=fLO⁢1-fRF, and fIF⁢=fLO⁢2-fMF