Synthetic Aperture Radar (SAR), despite being an active microwave imaging sensor, is not immune to RFI, which can significantly compromise the integrity and reliability of acquired data. At the same time, the increasing frequency and severity of natural disasters driven by climate change reinforce the need for continuous, accurate monitoring of the Earth’s dynamic environment. SAR plays a key role here thanks to its ability to operate regardless of weather or lighting conditions. 

In this context, the detection, characterisation, and mitigation of RFI have become critical to ensuring reliable SAR data for disaster prediction, monitoring, and damage assessment.

The approach: a modular RFI simulator

To address this need, we developed a modular software framework that simulates multiple types of RFI at raw data level and injects them into clean Sentinel-1 acquisitions. The simulator serves two purposes.

First, it provides a controlled environment to evaluate the performance of conventional detection and mitigation techniques, identify their limitations, and explore potential improvements.

Second, and equally important, it enables the generation of a synthetically contaminated and accurately labelled dataset, which is essential for training Deep Learning models. Reliable labels are notoriously hard to obtain when working with real-world RFI, and a high-fidelity simulator helps achieve good generalisation while reducing the risk of domain shift when these models are later applied to operational data.

What the project delivered

The thesis combines three contributions in a single framework: a modular implementation of multiple RFI types at raw processing level, a set of detection and mitigation algorithms integrated under a common evaluation framework that enables fair comparison, and a labelled dataset designed to train Deep Learning models capable of detecting RFI before SAR focusing, where mitigation is most effective.

Making it possible at Zenithal Blue

The purpose of a master’s thesis is to push into the borders of knowledge in a specific field. Thanks to Zenithal Blue, I was able to do exactly that: explore new directions for the company while laying the foundation of my own career, at least for the coming years through a PhD. The trust the company placed in me was the main reason I stayed motivated and felt capable of taking the project on.

For a master’s student taking the first steps into the space sector, collaborating with highly skilled professionals is an invaluable experience. Being part of a company involved in top-tier projects and feeling like a real contributor rather than an observer is something not every student gets to experience, and it has made all the difference.

La entrada Simulating radio frequency interference in Sentinel-1 at raw data level se publicó primero en Zenithal Blue.

The work carried out by our newest member, Andreu Melis, whilst studying for his Master’s degree at the Universitat Politècnica de Catalunya (UPC), in collaboration with Professor Adriano Camps, has recently been published in IEEE Access. 

The article assesses whether that subsurface moisture can be estimated from multi-frequency microwave radiometry. It combines an information-content analysis with an algorithmic feasibility study, comparing two retrieval approaches built around a five-parameter model of the soil-moisture profile, and evaluates how multi-polarized observations and multiple incidence angles improve the estimation. The results characterise the conditions under which root-zone soil moisture can be recovered radiometrically, a question with direct relevance to hydrology, agriculture and climate monitoring.

Our contribution 

This paper is the published research of Andreu Melis, now a full-time member of the Zenithal Blue team. It originated during the Introduction to Research module of the MATT Master’s programme at the Universitat Politècnica de Catalunya (UPC), in collaboration with Professor Adriano Camps. It reflects the radiometry and remote-sensing expertise Andreu brings to our work in Earth observation.

Medium 

IEEE Access (open access) · [Published on 1st September 2026] 

https://ieeexplore.ieee.org/document/11674113/

La entrada Advancing soil moisture retrieval: a team member’s Master’s research, now published se publicó primero en Zenithal Blue.

Our main client to date has been the European Space Agency (ESA), an organization with a clear scientific and industrial vocation and a well-defined goal: to transfer the knowledge generated in academia and specialized industry to a broader cross-section of society. That approach has worked so well that Europe is now home to some of the organizations with the deepest expertise in aerospace technology in the world.

Working in that environment forces you to think beyond the quarter. And that fits perfectly with who we are.

Small companies have something that can sometimes get diluted in large ones

Zenithal Blue is a relatively small company. And that’s an advantage in what matters most to us: the strength of conviction about what you do. In our case, we share that conviction as a team, which is the desire to work on projects that genuinely have an impact on society.

This isn’t an empty statement of intent. The kind of projects we seek out, and the ones we decide not to take on, prove it. We work on projects that provide vital information for better understanding the global climate and the impact of climate change. We work on the design of future missions to observe the Earth and solve problems that are critical for society. And we work on developing dual-use technologies to protect European interests and values.

These are areas of work that we actively pursue because we believe in them.

Economic profit is not the enemy of purpose

It’s important to make one thing clear: the pursuit of purpose isn’t incompatible with economic viability. Publicly traded companies have shareholders who expect a return on their investment, and that’s legitimate. But that doesn’t exhaust or define the full spirit and actions of a company, nor its purpose toward society.

At Zenithal Blue, economic sustainability is a necessary condition for being able to do the work we want to do. It isn’t the end goal. The end goal is impact.

A highly qualified team in service of what we believe matters

Every member of the team holds a very high level of academic qualification: PhDs and engineers, with experience accumulated across long-term projects. We put that experience in service of what we believe we can do best for society.

And in a sector as competitive and as oriented toward technical excellence as aerospace, that’s not a luxury. It’s a decision we make every time we choose a project.

La entrada A company with purpose: why we do science from within a startup se publicó primero en Zenithal Blue.