PASSIVE RADAR — AMBIENT SIGNAL EXTRACTION

GRAPHOLOGY v1.0

THE RESIDUAL IS THE TARGET

Conventional radar uses matched filters + CFAR thresholding. They discard everything below the noise floor. We keep it. The Cross-Ambiguity Function χ(τ,f_d) correlates reference and surveillance channels. The CLEAN algorithm removes direct path. What remains is R[n] — the pixels before the blip.

ILLUMINATOR OF OPPORTUNITY

FREQUENCY CONFIG

Center: 98.1 MHz

Bandwidth: 200 kHz

Integration: 100 ms

DETECTION

CFAR Threshold: 12 dB

Show residual only

Detected Targets

CONTROL

Residual Energy

0.000e+0

RANGE-DOPPLER MAP (CLEANED)

χ(τ,f_d) after CLEAN — Direct path removed, bistatic reflections visible

REFERENCE vs SURVEILLANCE

Reference: illuminator direct path. Surveillance: reflections + leakage

THE RESIDUAL — R[n] = x_surveillance - (x_reference * Laws)

What conventional systems discard. The signal that exists before it becomes a detection. When R[n] ≠ 0, there is information the matched filter cannot explain.

RTL-SDR BLOG V4 INTEGRATION

Currently running simulation. For real passive radar, connect RTL-SDR via WebUSB or pipe IQ data through WebSocket. Requires two synchronized receivers: one pointed at illuminator (reference), one at surveillance area. The mathematics is identical — only the input changes.

# Real SDR command (external)
rtl_sdr -f 98.1M -s 200k -g 40 - | nc localhost 1234

# WebSocket bridge receives IQ samples
# Frontend applies: DEDUCE → DEQUANTIFY → DECOUPLE → DEMODULATE → R[n]

"They throw away everything below the noise floor. We kept it."

THE RESIDUAL IS THE TARGET