Demo — DRFM Deception#
Noise jamming shouts at the radar; deception lies to it. A digital RF memory (DRFM) captures the threat’s own pulse and replays modified copies that look exactly like real skin returns — and the classic move, range-gate pull-off, walks the radar’s tracking gate right off the target. This demo animates that sequence step by step.
The idea#
The radar tracks inside a range gate. A DRFM false return, made brighter than the skin echo, captures the gate, then ramps its delay to drag the gate out in range (recall \(R = c\,t/2\)). When the false return blinks off, the gate is left coasting on empty space and the true target has slipped free.
Interactive demo#
Walkthrough#
Press Play and watch the capture. The DRFM false return (red) sits on the true target (navy) but louder; the tracking gate (blue) locks to the stronger return.
Watch the pull-off. The false return walks out in range, dragging the gate with it while the true target stays put. The separation readout grows.
Watch the blink. The false return switches off. The gate is now far downrange on nothing, and the true target is outside it — the lock is broken.
Change the walk-off rate. A faster pull-off breaks lock sooner but is easier for a deception-aware radar to reject; a slower one is stealthier. Reset and run it again.
Key observations#
Deception attacks the measurement, not the power budget. Unlike noise jamming, it does not have to overpower the echo — it only has to be believed.
DRFM works because it is coherent. Replaying the radar’s own waveform produces a false return that passes the matched filter as genuine.
Every move has a counter. Leading-edge tracking and other ECCM eventually reject the walked return — the cycle from L11 continues.
Source#
MATLAB · code/L18_RangeGatePullOff.m↓
The in-class script models the tracking gate, captures it with a cover pulse, ramps the false return’s delay to walk the gate off the target, then blinks it off so the true target escapes.