M3 Systems (M3S) is a family‑owned SME founded in 1999 in Toulouse, specializing in radio‑frequency signal processing, with a strong focus on radionavigation (GNSS) and Air Traffic Management (ATM). Over the years, M3S has developed recognized European‑level expertise in GNSS, serving aerospace and defense markets as well as critical applications requiring guaranteed positioning integrity, accuracy, availability, and continuity. M3S operates a dedicated radionavigation expert team and develops the STELLA‑NGC GNSS testbed, a versatile SDR suite for GNSS receiver performance assessment under nominal and non‑nominal conditions, including multipath, scintillation, jamming, and spoofing. The company delivers consulting, R&D, and test and measurement solutions across aeronautics, defense, space, and transportation domains.