Prototyping Cooperative Radio Navigation for Planetary Exploration with Software-Defined Radios

Reliable radio communications as well as position, navigation and timing (PNT) are crucial for planetary exploration missions. Prototyping, experiments and analogue missions are vital to increase the technology readiness level (TRL). Software-defined radios (SDRs) are perfectly suited for such tasks due to their flexibility and comparably low implementation effort. With the this paper, we introduce a software architecture for cooperative radio navigation, which can be adapted for different experiments and hardware setups. We showcase three measurements and experiments in analogue environments with distinct requirements. First, we show how accurate time-of-flight (ToF) measurements can be achieved with single-channel SDRs and present radio channel and ranging measurements inside a lava tube. Second, we introduce a coherent multi-channel SDR setup for direction-of-arrival (DoA) estimation and demonstrate cooperative radio navigation of robotic rovers on a volcano. Third, we present a two-channel SDR for hybrid lunar navigation, capable of simultaneously performing ranging with neighboring nodes and receiving satellite navigation signals. We conclude that, with careful setup and calibration, SDRs are well suited to develop flexible and accurate radio navigation systems.