# Demo — IADS Coverage Explorer

This demo makes the layered-defense story tangible. Three coverage rings — an EW surveillance radar, an ACQ acquisition radar, and a TTR fire-control radar — are drawn to scale around a notional adversary site. Slide the target's radar cross-section (RCS) and watch every ring collapse together, and read off exactly how many kilometers low-observable design buys at each layer.

## The idea

Each ring is a maximum detection range from the fourth-power law, $R_{\max}\propto\sigma^{1/4}$. Drop the RCS and every ring shrinks by the same **percentage** — but the **absolute** kilometers removed are largest where the ring started largest.

$$
R_{\max}(\sigma) = R_{\text{ref}}\cdot 10^{\,\sigma_{\text{dBsm}}/40}.
$$

## Interactive demo

<a class="demo-fullscreen" href="../_static/demos/IADSCoverageExplorer.html" target="_blank" rel="noopener">Open in full screen</a>

<div class="demo-wrap">
<iframe src="../_static/demos/IADSCoverageExplorer.html"
        title="Interactive IADS coverage explorer"
        width="100%"
        loading="lazy">
</iframe>
</div>

## Walkthrough

1. **Start at σ = 0 dBsm (legacy fighter).** Note the layered ring of defenses — a wide EW ring, a medium ACQ ring, a small TTR ring, all centered on the site.
2. **Slide σ down to −30 dBsm (B-21).** All three rings collapse. Watch the readout table: the EW ring loses the most **absolute** kilometers, while every radar shows the **same** percent reduction.
3. **Flip between presets.** Jump between *Legacy (0)* and *B-21 (−30)* and confirm the L7 type-along's claim — LO buys the most absolute kilometers at the outer (EW / ACQ) layer.
4. **Reposition a radar.** Drag any radar marker to offset its coverage from the site, and add the **AI** ring to see the terminal layer close in even on a stealthy target.

## Key observations

- **Same percent, different absolute.** The fourth-power law guarantees an identical fractional shrink at every layer; the outer rings simply have more kilometers to lose.
- **LO is standoff, not invisibility.** Even at −30 dBsm the inner rings remain — the engagement layers still close in, which is why later blocks add active EW.
- **Geometry matters.** Repositioning radars changes where the layered coverage actually overlaps — gaps in coverage are exactly what a mission planner hunts for.

## Source

<a class="matlab-link" href="../_static/downloads/ECE%20495%20EW%20%E2%80%93%20Code.zip#code/L7_IADSRadarSurvey.m" download><svg viewBox="0 0 22 22" width="14" height="14" aria-hidden="true" style="vertical-align:-2px;margin-right:6px;"><rect width="22" height="22" rx="3" fill="#e87722"/><text x="11" y="15.5" text-anchor="middle" font-family="'Inter',sans-serif" font-size="9" font-weight="800" fill="#fff" letter-spacing="-0.04em">MAT</text></svg><span class="ml-text">MATLAB · code/L7_IADSRadarSurvey.m</span><span class="ml-arrow">↓</span></a>

The in-class script tabulates notional $P_t$, $G$, $\lambda$, and $S_{\min}$ for the EW, ACQ, TTR, and AI classes, computes $R_{\max}$ against a $1\ \text{m}^2$ target and a $-30$ dBsm B-21, and shows where LO buys the most absolute kilometers.