Reactive jamming technology

How Defender's reactive jamming works, and how it compares to other architectures

Reactive jamming detects a threat transmission and directs jamming energy at its exact frequency within microseconds, instead of broadcasting continuously across the whole band. B4 Limits implements this in FPGA hardware, enabling 18 μs response and the tracking of frequency-hopping signals that defeat conventional VCO and DDS jammers.

Explore the technology

How the reactive approach works, and how it compares to VCO and DDS architectures.

Why FPGA

Detection, classification and jamming-waveform generation execute as parallel hardware pipelines on the same FPGA fabric rather than sequential software steps — the source of microsecond-class timing. The fabric is field-reprogrammable, so new threat protocols are countered with a software profile rather than a hardware revision.

From technology to platform

The reactive architecture described above is the same across every Defender system — the platforms differ in how that capability is packaged and scaled, not in how the jamming works.

The Defender Modular series scales from a single man-portable module to a multi-module array operating as one coordinated jammer, with power, bandwidth, and coverage area increasing as modules are added — distributed across terrain for wide-area coverage, or co-located to concentrate output. The Defender Manpack is a self-contained unit in a ~32 kg man-portable chassis for dismounted operations, checkpoints, and rapid deployment. Both share the same reactive modes, the same Leo control software, and the same REST and SAPIENT integration, and can operate together in a synchronised network.