Wireless Software Engineer – SDR

Location: Hybrid, Copenhagen Full-time · Visa sponsorship available Role Summary We are looking for a software engineer who lives in the signal-processing layer of Software Defined Radio. You will build the software that turns raw I/Q from our SDR front-ends into reliable, real-time detection, classification and localisation of wireless emitters – from the low-level sample pipeline and DSP blocks through to the services and interfaces the rest of the product is built on. Key Responsibilities

• Design and implement real-time I/Q processing pipelines in C++ and Python: channelisation, filtering, resampling, synchronisation, demodulation and detection.
• Build and maintain SDR applications on GNU Radio and/or custom frameworks, including out-of-tree blocks and streaming architectures for continuous wideband capture.
• Implement signal detection, classification and parameter estimation (energy and cyclostationary detection, burst segmentation, carrier and symbol-rate estimation, modulation recognition).
• Implement direction-finding and localisation algorithms (phase interferometry, MUSIC/ESPRIT, TDoA) on coherent multi-channel SDRs.
• Drive SDR hardware from software: tuning, gain and sample-rate control, PPS/GPSDO timing, multi-channel phase coherence and calibration (USRP/UHD, AD936x, Matchstiq/Sidekiq-class platforms).
• Optimise for real-time performance: multi-threading, lock-free buffering, SIMD, GPU acceleration and profiling, to sustain wideband sample rates without drops.
• Build the surrounding software: capture and recording tools, replay and offline analysis, telemetry, configuration, and interfaces to the rest of the system.
• Work with the RF hardware and FPGA side on interfaces, data formats and system-level performance, and support lab measurement and field trials.
• Contribute to testing and validation: unit tests on synthetic signals, regression against recorded captures, and repeatable over-the-air test procedures.

Required Qualifications

• Strong C++ (modern C++14/17 or newer) and Python, with a track record of production-quality, performance-sensitive code.
• Solid grounding in digital signal processing: sampling, filtering, FFT and spectral estimation, synchronisation, and digital modulation.
• Hands-on experience developing on SDR platforms (USRP/UHD, AD936x or equivalent) and working with live I/Q data.
• Experience with GNU Radio or a comparable streaming DSP framework.
• Comfortable with Linux development, CMake, Git, and debugging real-time systems.
• Able to reason about a signal chain end to end – and to work from a spectrum analyser trace or a recorded capture back to a bug in the code.

Nice-to-Haves

• Wireless protocol knowledge (Wi-Fi, Bluetooth/BLE, LoRa, DSSS/FHSS control links, OFDM systems, LTE/5G NR).
• Experience with wideband spectrum monitoring, passive sensing or emitter localisation.
• Machine learning applied to RF (signal classification, RF fingerprinting), with PyTorch or similar.
• GPU or accelerated DSP (CUDA, VkFFT) and embedded targets (Jetson, Zynq/ZynqMP, ARM SoCs).
• FPGA exposure (RFNoC, Vivado, HDL) or experience defining hardware/software interfaces.
• Containerisation, CI/CD, and deployment to embedded or field-deployed systems.