tleloader.js

/* TLELOADER.JS / JoEmbedded */
// Info about TLE: https://en.wikipedia.org/wiki/Two-line_element_set
// Original Source: https://celestrak.org/NORAD/elements/gp.php?GROUP=active&FORMAT=tle

// Cache download to ./data: via (e.g. by CRON) TLE-Data are valid for at least several days
// curl -o tledata.txt "https://celestrak.org/NORAD/elements/gp.php?GROUP=active&FORMAT=tle"

import * as SAT from "./modules/satellite.min.js" // install via npm install satellite.js
import {
    StaticCopyUsage, TrianglesDrawMode
} from "./modules/three.module.min.js"


export var SatList = [] // Contains Satrecs of ALL available LEO Sats
export var SelSatList = [] // List of Selected Sats

// Debug-Terminal
var MAXTERM = 100 // Lines for Terminal
var terminalContent = []

function Terminal(txt, flush = true) {
    while (terminalContent.length > MAXTERM) terminalContent.shift()
    terminalContent.push(txt)
    if (flush) {
        const h = document.getElementById('id_txt').innerText = terminalContent.join(' | ')
    }
}

// --- Functions ---
// Split URL Parameters
export function splitUrl(){
    let qs = location.search.substring(1).split('&')
    let urlpar = {}
    for (let x = 0; x < qs.length; x++) {
    let kv = qs[x].split('=')
    if (kv[1] === undefined) kv[1] = ''
        urlpar[kv[0]] = kv[1]
    }
    return urlpar;
}



async function fetchData(file) { // ATTENTION: Fetch only via HTTP
    try {
        let response = await fetch(file)
        if (response.status === 200) {
            let data = await response.text()
            return data;
        } else throw "File: '" + file + "': " + response.status + ": " + response.statusText
    } catch (err) { // Catch e.g. CORS Errors
        return "ERROR: " + err // 'ERROR: Magic first word
    }
}

const MinutesPerDay = 1440;
const ixpdotp = MinutesPerDay / (2.0 * 3.141592654)

/* Load List of all currently active LEO Satellites */
export async function loadTLEList() {
    // Original Source: https://celestrak.org/NORAD/elements/gp.php?GROUP=active&FORMAT=tle
    // Periodic (cached) Copy: https://joembedded.de/x3/leoview/data/tledata.php
    let dataurl
    if(location.hostname == 'localhost'){
        dataurl = './data/tledata.txt'
    }else{
        dataurl = 'https://joembedded.de/x3/leoview/data/tledata.php'
    }

    const res = await fetchData(dataurl) // Load global TLE List
    if (res.startsWith('ERROR: ')) {
        alert("\u274C ERROR:\nNo TLE Data found.\nReason: '" + res.substring(7) +
            "'")
    } else {
        SatList = []
        try {
            var tmplist = res.replace(/\r/g,'').split("\n")
            for (let i = 0; i < tmplist.length; i += 3) {
                let hname = tmplist[i].trim()
                let hl0 = tmplist[i + 1].trim()
                let hl1 = tmplist[i + 2].trim()
                if (hname.length && hl0.startsWith('1') && hl1.startsWith('2')) {
                    const sr = satellite.twoline2satrec(hl0, hl1);
                    if (sr.error) {
                        console.log("loadTLEList(): Error " + sr.error + " for TLE '" + hname.length + "'")
                        continue; // Error in TLE-Data
                    }
                    const revsPerDay = sr.no * ixpdotp;
                    if (revsPerDay < 6.4) continue; // A LEO St has per Def. <225 minutes per orbit!
                    const h = {
                        name: hname, // name of Sat
                        sr: sr, // propagation satrec
                        sat3Obj: null, // Reserve Space for THREE Satelite object
                        satPos: null, // Position obj
                        track: null,    // Track as Option
                    }
                    SatList.push(h)
                }
            }
        } catch {}
    }
}

// Accepts aLiszt of comma separated operators e.g. spacbee,astrocast,
export function buildSelectedSatList(selmask) {
    const sellow = selmask.toLowerCase()
    SelSatList = []

    const selmarr = sellow.replace(/,*$/, '').split(',').map((e)=>e.trim()) // Remove last comma ans WSs
    SatList.forEach((e) => {
        const snlo = e.name.toLowerCase();
        if(selmarr.find(e => snlo.startsWith(e)) !== undefined){
            SelSatList.push(e)            
        }
    })
    return SelSatList.length
}

// Calculate one Position
export function calcSrPositionEci(satrec, date) {
    const positionAndVelocity = satellite.propagate(satrec, date)
    if(satrec.error) return;    // undefined

    const gmst = satellite.gstime(date)
    const position = satellite.eciToGeodetic(positionAndVelocity.position, gmst);
    
    const hpos = {
        lng: position.longitude,
        lat: position.latitude,
        alt: position.height,
    }
    return hpos;
}

const CALCV = false // true // Speed only if necessary
// Calculate current Positions
export function calcPositions(date = new Date()) {
    for (let i = 0; i < SelSatList.length; i++) {
        const satsel = SelSatList[i]
        const satrec = satsel.sr;
        if (satrec.error) continue; // Removed from List
        try {
            const positionAndVelocity = satellite.propagate(satrec, date)
            if(satrec.error){
                throw "satrec.error:"+satrec.error;
            }
            const gmst = satellite.gstime(date)
            const position = satellite.eciToGeodetic(positionAndVelocity.position, gmst);

            var vtotal
            if (CALCV) {
                const velocity = positionAndVelocity.velocity;
                vtotal = Math.sqrt(velocity.x * velocity.x + velocity.y * velocity.y + velocity.z * velocity.z)
            } else vtotal = 0
            /*
            console.log("Name: ",SatListSel[i].name)
            console.log("Lng:", satellite.degreesLong(position.longitude).toFixed(3)); // p.l in radians
            console.log("Lat:", satellite.degreesLong(position.latitude).toFixed(3)); // p.l in radians
            console.log("Altitude(km):", position.height.toFixed(3)); 
            //console.log("Speed(km/sec): "+vtotal.toFixed(3)); 
            */
            const hpos = {
                lng: position.longitude,
                lat: position.latitude,
                alt: position.height,
                speed: vtotal
            }
            SelSatList[i].satPos = hpos
        } catch (e) {
            console.log("calcPositions(): Problem '" + e + "' with '" + SelSatList[i].name + "'")
            SelSatList[i].satPos = null
        }
    }
}





/****/