DRFM stands for Digital Radio Frequency Memory.

At a simple level, a DRFM can be explained as a very fast digital recorder for radar signals. It receives a radar waveform, converts it into digital samples, stores it, modifies it, and then retransmits a controlled version of the same signal.

The important point is coherence. Because the retransmitted waveform is derived from the original radar signal, the radar receiver may process it as if it were a real echo from a real target.

In the basic demonstration, the radar sends a pulse toward a target. The DRFM captures the pulse, stores a digital copy, applies a controlled change, and sends it back. The radar display then shows a return that appears shifted, duplicated, or altered.

In the technical view, the chain is shown as receive, down-convert, analog-to-digital conversion, digital memory, signal manipulation, digital-to-analog conversion, up-conversion, and retransmission.

Typical conceptual effects include range displacement, Doppler or velocity displacement, multiple false targets, amplitude shaping, and coherent noise concepts. This lesson keeps the explanation educational and does not provide operational parameters for real systems.

The purpose of this demonstrator is to help students understand why DRFM is central to modern radar deception: it does not merely add noise; it creates a believable signal history that can interact with radar processing.