Sats

server/src/sats.mjs

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+import {cfg} from './config.mjs';
+import {isEqual} from '@ztimson/utils';
+
+const HISTORY_LIMIT = 500
+const POLL_MS = 5_000
+const TTL_MS = 15 * 60_000 // drop a satellite's bucket if nothing new for 15 min
+
+function parseWm(raw) {
+	const f = raw.replace(/<[^>]+>/g, '').split(',').map(s => s.trim());
+	const [latitude, longitude] = f[15].split('/').map(s => parseFloat(s));
+	const [az, el] = f[16].split('/').map(s => parseFloat(s));
+	return {
+		timestamp: Date.now(),
+		freqMHz: parseFloat(f[3]),
+		satellite: f[14],
+		latitude, longitude,
+		az, el,
+		packetRssi: parseFloat(f[21]),
+		packetSnr: parseFloat(f[22]),
+		freqError: parseFloat(f[23]),
+		crcOk: !/CRC ERROR/i.test(f[24]),
+	}
+}
+
+const satellites = new Map();
+
+function pruneStale() {
+	const now = Date.now();
+	for (const [name, bucket] of satellites) {
+		if (now - bucket.lastSeen > TTL_MS) satellites.delete(name);
+	}
+}
+
+export async function pollTinyGS() {
+	const { TINYGS_URL, TINYGS_AUTH } = cfg();
+	try {
+		const raw = await fetch(TINYGS_URL + '/wm', {
+			headers: TINYGS_AUTH ? {Authorization: `Basic ${TINYGS_AUTH}`} : {}
+		}).then(r => r.text());
+		const reading = parseWm(raw);
+		if (!reading.satellite || reading.satellite === '-') return;
+
+		let bucket = satellites.get(reading.satellite);
+		if (!bucket) {
+			bucket = { history: [], lastSeen: 0 };
+			satellites.set(reading.satellite, bucket);
+		}
+
+		bucket.lastSeen = reading.timestamp;
+		if (!isEqual(bucket.history.at(-1), reading)) {
+			bucket.history.push(reading);
+			if (bucket.history.length > HISTORY_LIMIT) bucket.history.shift();
+		}
+
+		pruneStale();
+	} catch (err) {
+		console.error('[tinygs] poll failed', err);
+	}
+}
+
+setInterval(pollTinyGS, POLL_MS);
+
+export const getTinyGSData = () => {
+	pruneStale();
+	return Array.from(satellites.entries()).map(([name, bucket]) => ({
+		...bucket.history.at(-1),
+		history: bucket.history.slice(0, -1),
+	}));
+}