Software Engineer - Defence

Software Engineer (C++ | Signal Processing | Algorithms | UML)

Location: Southwest England (hybrid options depending on project)

Sector: Maritime defence and security technology

Holt Engineering is working with an international engineering business that develops advanced maritime systems used by navies worldwide, spanning sonar/hydroacoustics, sensor-to-decision solutions, and command & control capabilities. Work sits at the intersection of real-world physics, high-performance software, and mission critical reliability.

You’ll design and build software that turns complex sensor data into actionable outputs, including detection, classification and tracking of underwater targets. You’ll work in multi-disciplinary teams (software, systems, test, and hardware) and contribute across the full lifecycle: requirements, architecture, implementation, verification, and support.

• Develop C++ components for performance-critical, real-time or near real-time processing pipelines.
• Design and document software architecture using UML (e.g., class diagrams, sequence diagrams, state models).
• Implement and optimise signal processing and algorithm development for detection/classification/tracking workflows.
• Apply strong object-oriented programming principles (SOLID, clean architecture, maintainable patterns).
• Write unit/integration tests, support verification activities, and contribute to continuous improvement of coding standards.
• Collaborate with Systems Engineering to translate requirements into robust designs and deliverable increments.

• Strong commercial experience in C++.
• Proven signal processing experience (e.g., filtering, spectral analysis, detection theory, estimation, tracking).
• Demonstrable algorithm development (from concept to validated implementation, including performance tuning).
• Confident use of UML for software design and communication.
• Solid OOP fundamentals and experience building maintainable, testable codebases.

• Experience with real-time constraints, multi-threading, latency/performance optimisation.
• Familiarity with sensor fusion, tracking (e.g., Kalman/particle filters), classification, feature extraction.
• Experience in safety/mission-critical engineering environments (e.g., rigorous V&V, secure development practices).
• Linux development, modern build tooling (CMake), Git-based workflows, CI/CD.