refactor: extract typed auto bandwidth estimator

2026-08-01 17:59:04 +02:00
parent 1fb196a64e
commit e300cc343d
4 changed files with 241 additions and 174 deletions
@@ -0,0 +1,56 @@
+// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+import assert from "node:assert/strict";
+import test from "node:test";
+import vm from "node:vm";
+import { build } from "esbuild";
+
+async function loadEstimator() {
+  const result = await build({
+    entryPoints: [new URL("../src/features/radio/auto-bandwidth.ts", import.meta.url).pathname],
+    bundle: true,
+    format: "cjs",
+    platform: "browser",
+    target: "es2022",
+    write: false,
+  });
+  const module = { exports: {} };
+  vm.runInNewContext(result.outputFiles[0].text, {
+    module,
+    exports: module.exports,
+    Array,
+    ArrayBuffer,
+    Number,
+    Math,
+  });
+  return module.exports.estimateOccupiedBandwidth;
+}
+
+function wfmFrame(signalHalfWidthHz, signalDb = -70) {
+  const sampleRate = 400_000;
+  const bins = Array.from({ length: 1025 }, (_, index) => {
+    const offsetHz = (index / 1024 - 0.5) * sampleRate;
+    return Math.abs(offsetHz) <= signalHalfWidthHz ? signalDb : -100;
+  });
+  return { bins, center_hz: 100_000_000, sample_rate: sampleRate };
+}
+
+test("weak WFM falls back to the 60 kHz intelligibility floor", async () => {
+  const estimate = await loadEstimator();
+  const weak = wfmFrame(90_000, -97);
+  assert.equal(estimate(weak, 100_000_000, "WFM", [180_000, 60_000, 300_000, 5_000]), 60_000);
+});
+
+test("WFM ACI and CCI cap an otherwise wide occupied estimate", async () => {
+  const estimate = await loadEstimator();
+  const frame = wfmFrame(95_000);
+  const limits = [180_000, 60_000, 300_000, 5_000];
+  const clear = estimate(frame, 100_000_000, "WFM", limits);
+  const adjacent = estimate(frame, 100_000_000, "WFM", limits, { aci: 100 });
+  const cochannel = estimate(frame, 100_000_000, "WFM", limits, { cci: 100 });
+  assert.ok(clear > adjacent);
+  assert.equal(adjacent, 60_000);
+  assert.ok(cochannel >= 135_000 && cochannel < clear);
+});