INTERNSHIP - Distributed Acoustic Sensor - M/F

Let's build a future of trust together

Thales is a global high-tech leader specializing in three sectors: Defense & Security, Aerospace & Space, and Cyber & Digital. It develops products and solutions that contribute to a safer, more environmentally friendly, and more inclusive world. The Group invests nearly 4 billion euros per year in Research & Development, particularly in key innovation areas such as AI, cybersecurity, quantum, cloud technologies, and 6G. Thales has nearly 81,000 employees in 68 countries.

Our commitments, your benefits

• Our technological expertise
• Our attention to employee work-life balance
• An inclusive and benevolent environment
• Recognized societal and environmental commitment (Thales Solidarity, CAC 40 ESG index…)

Your daily life

The Gennevilliers Campus is the heart of design, development, and support activities for major defense systems: radiocommunications, resilient network and infrastructure systems, satellite communications, collaborative combat, and cybersecurity. Located north of Paris, it is quickly accessible by public transport.

Within the DES department, responsible for electromagnetic hardening, you will join the DEM (Hardening, Equipment, and Measurement) group, composed of 15 people.

This internship aims to port and optimize treatments and post-treatments associated with the Distributed Acoustic Sensor on Optical Fiber (DAS-FO) process onto a software-defined radio (SDR) digital architecture (National Instrument USRP X410 cards).

The DAS-FO process exploits Rayleigh Back Scattering (RBS) induced by residual impurities in optical fibers on laser illumination to measure frequency shifts or phase shifts in the backscattered signal, which are induced by index fluctuations along the fiber. These fluctuations themselves vary linearly according to the different physical fields surrounding the fiber: pressure, mechanical or acoustic vibration, etc. Applications include measurement, non-destructive testing, and intelligence in vibro-acoustic environments.

Existing DAS-FO digital treatments apply to single-mode optical fibers and I/Q signals at the output of optical conversion after low-band filtering: estimations of delays, frequency shifts, and phase shifts, followed, if applicable, by frequency or phase demodulations. The goal will be to optimize their software porting to SDR, sequencing, numerical efficiency, and exploitation for aeroterrestrial applications on single-mode fiber, with a view to their future adaptation to multimode fibers.

The intern will work within a multidisciplinary technical team developing advanced sensors and modeling/simulations. Their supervisors will provide technical guidance and the necessary resources (documentation, explanations, SDR, and associated calculator) to support their work.

Your missions

By joining us, your main missions will include:

• Understanding the state of the art in DAS-FO and related treatments. Investigating existing head-end and exploitation post-treatments.
• Porting head-end DAS-FO treatments onto SDR and its associated calculator:
• I/Q signal processing – ambiguity calculation by matched filtering, estimation of delays, frequency shifts, and phase shifts,
• Antenna treatment – optical fiber approach as a sampled linear antenna, exploitation of curvilinear abscissa resolution, beamforming, spatial source separation,
• Porting DAS-FO exploitation post-treatments onto SDR and its associated calculator:
• Acoustic signal demodulation
• Identification and localization of acoustic sources
• Production of audio signals – ambiance analysis, enhancement treatments (sensitivity, intelligibility) – denoising
• Validating and testing the performance of DAS-FO ported on SDR: audio intelligibility, localization performance. Conducting probationary tests in laboratory conditions and comparing their results with those of the test campaign carried out by Thales SIX in May-June 2024.
• Synthesizing and presenting all developments and tests.

You will focus on porting existing treatments dedicated to single-mode fibers. Depending on the progress of the internship, we will seek to extend the treatments to multimode fibers, relying notably on the strong coherence of laser signals and on channel estimation and equalization techniques that exist in radio communications.

The internship may, if applicable, lead to a thesis dedicated to a prospective passive DAS-FO process, without the use of a laser illuminator, working from optical communication signals transiting in the optical fiber.

Your profile

You are currently pursuing a BAC+5 level higher education degree with a specialization in signal processing, IT development, and, if possible, optics.

You have skills such as:

• Technical skills in signal processing.
• Proficiency in mathematical tools + signal processing software (MATLAB, etc.).
• Proficiency in IT development in a Linux environment.
• Ability to analyze and synthesize scientific and technical articles.
• Technical skills in optics: optical fibers, lasers
• Ability to write technical documents
• Ability to synthesize and give oral presentations
• Autonomy
• Curiosity, initiative, teamwork, pedagogy, and analytical skills

A word from the team

We hope you will join us soon on this technically very interesting subject.

All our internships are conventioned and subject to gratification, the amount of which is determined according to your level of study.

Thales, a Handi-Engaged company, recognizes all talents. Diversity is our best asset. Apply and join us!