YOFC modular RF optical delay line system is capable of achieving true-time delay of broadband microwave signals with high precision, tunability, and scalability. Comparing with the conventional microwave coaxial or waveguide based solutions, the system possesses multiple advantages, such as wide frequency range, high consistency over frequency, good repeatability, low loss dependence on delay values, and flexible scalability. The system adopts pluggable blade modular design, which mainly consists of a 3U 19” rack chassis, RF optical transceiver module, multiple fibre-optic delay module, optical amplifier module (optional), and control module. The true-time delay figures can be configured onsite or remotely.