Demo — IADS Coverage Explorer

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#

Open in full screen

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 demo’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.

  5. Now press B-21 (band-dependent). This is the same aircraft, but each radar now sees the B-21’s RCS in its own band — UHF \(-17.9\), S \(-25.5\), X \(-32.0\) dBsm, the nose-on row of the Project 1 RCS table. The rings stop collapsing together, and the % cut column stops agreeing with itself. Compare it against the flat B-21 (−30) preset and ask which picture a mission planner should route against.

Key observations#

  • Same percent, different absolute. With one σ for every radar, the fourth-power law guarantees an identical fractional shrink at every layer; the outer rings simply have more kilometers to lose.

  • One σ is a convenient lie. Broadband LO suppresses hardest at high frequency, so the EW radar sees a much larger target than the TTR does. The band-dependent preset is the honest version — and it is exactly the problem Project 1 hands you at L9, where the same RCS table runs across all aspects instead of just nose-on.

  • 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. Dragging a radar moves its ring off the site, so you can see how the layers overlap when the emitters are not co-located. The ranges do not change — only where the coverage sits.

Source#

MATLAB bundle · L7_IADSRadarSurvey.m↓

The companion 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.

Note

The demo’s anchor rings — 700 / 470 / 150 / 80 km — are the lesson’s narrative ranges, the round numbers the reading and the taxonomy table use. The companion script starts from the graded \(S_{\min}\) values instead and computes 692 / 474 / 146 / 82 km. Both are deliberate: the narrative keeps the rings memorable, the script keeps the physics exact. Project 1 and HW1 are graded against the script’s world.

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