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https://github.com/rt-bishop/Look4Sat.git
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Cleaned up the code in PassPredictor class
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Arty Bishop committed
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@@ -21,12 +21,13 @@ package com.rtbishop.look4sat
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import android.net.Uri
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import androidx.lifecycle.*
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import com.github.amsacode.predict4java.SatelliteFactory
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import com.rtbishop.look4sat.data.*
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import com.rtbishop.look4sat.repo.EntriesRepo
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import com.rtbishop.look4sat.repo.SourcesRepo
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import com.rtbishop.look4sat.repo.TransmittersRepo
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import com.rtbishop.look4sat.utility.PassPredictor
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import com.rtbishop.look4sat.utility.PrefsManager
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import com.rtbishop.look4sat.utility.getPredictor
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import dagger.hilt.android.lifecycle.HiltViewModel
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import kotlinx.coroutines.Dispatchers
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import kotlinx.coroutines.delay
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@@ -128,7 +129,7 @@ class SharedViewModel @Inject constructor(
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private fun getPasses(entry: SatEntry, dateNow: Date): MutableList<SatPass> {
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val gsp = prefsManager.getStationPosition()
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val predictor = PassPredictor(entry.tle, gsp)
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val predictor = SatelliteFactory.createSatellite(entry.tle).getPredictor(gsp)
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val hoursAhead = prefsManager.getPassPrefs().hoursAhead
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val passes = predictor.getPasses(dateNow, hoursAhead, true)
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val passList = passes.map { SatPass(entry.tle, predictor, it) }
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@@ -19,6 +19,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
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package com.rtbishop.look4sat.utility
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import com.github.amsacode.predict4java.GroundStationPosition
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import com.github.amsacode.predict4java.Satellite
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import java.util.concurrent.TimeUnit
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fun Long.formatForTimer(): String {
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@@ -34,3 +36,7 @@ fun Double.round(decimals: Int): Double {
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repeat(decimals) { multiplier *= 10 }
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return kotlin.math.round(this * multiplier) / multiplier
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}
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fun Satellite.getPredictor(stationPosition: GroundStationPosition): PassPredictor {
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return PassPredictor(this, stationPosition)
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}
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@@ -1,249 +1,141 @@
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/**
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* predict4java: An SDP4 / SGP4 library for satellite orbit predictions
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*
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* Copyright (C) 2004-2010 David A. B. Johnson, G4DPZ.
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*
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* This class is a Java port of one of the core elements of
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* the Predict program, Copyright John A. Magliacane,
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* KD2BD 1991-2003: http://www.qsl.net/kd2bd/predict.html
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*
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* Dr. T.S. Kelso is the author of the SGP4/SDP4 orbital models,
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* originally written in Fortran and Pascal, and released into the
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* public domain through his website (http://www.celestrak.com/).
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* Neoklis Kyriazis, 5B4AZ, later re-wrote Dr. Kelso's code in C,
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* and released it under the GNU GPL in 2002.
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* PREDICT's core is based on 5B4AZ's code translation efforts.
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*
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* Author: David A. B. Johnson, G4DPZ <dave></dave>@g4dpz.me.uk>
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*
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* Comments, questions and bugreports should be submitted via
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* http://sourceforge.net/projects/websat/
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* More details can be found at the project home page:
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*
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* http://websat.sourceforge.net
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, visit http://www.fsf.org/
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*/
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package com.rtbishop.look4sat.utility
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import com.github.amsacode.predict4java.*
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import com.github.amsacode.predict4java.GroundStationPosition
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import com.github.amsacode.predict4java.SatPassTime
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import com.github.amsacode.predict4java.SatPos
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import com.github.amsacode.predict4java.Satellite
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import java.util.*
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class PassPredictor(private val tle: TLE, private val qth: GroundStationPosition) {
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private val sat: Satellite = SatelliteFactory.createSatellite(tle)
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class PassPredictor(private val satellite: Satellite, private val qth: GroundStationPosition) {
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private val oneQuarterOrbitMin = (24.0 * 60.0 / satellite.tle.meanmo / 4.0).toInt()
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private val speedOfLight = 2.99792458E8
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private val timeZone: TimeZone = TimeZone.getTimeZone("UTC")
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private var iterationCount = 0
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private val polePassed = "none"
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fun getDownlinkFreq(freq: Long, date: Date): Long {
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val rangeRate = getSatPos(date).rangeRate
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return (freq.toDouble() * (speedOfLight - rangeRate * 1000.0) / speedOfLight).toLong()
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}
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fun getUplinkFreq(freq: Long, date: Date): Long {
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val rangeRate = getSatPos(date).rangeRate
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return (freq.toDouble() * (speedOfLight + rangeRate * 1000.0) / speedOfLight).toLong()
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}
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fun getSatPos(time: Date): SatPos {
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iterationCount++
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return sat.getPosition(qth, time)
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fun getSatPos(date: Date): SatPos {
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return satellite.getPosition(qth, date)
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}
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fun getPositions(
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referenceDate: Date,
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incrementSeconds: Int,
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minutesBefore: Int,
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minutesAfter: Int
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): List<SatPos> {
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val positions: MutableList<SatPos> = ArrayList()
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val endDateDate = Date(referenceDate.time + minutesAfter * 60L * 1000L)
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var trackDate = Date(referenceDate.time - minutesBefore * 60L * 1000L)
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while (trackDate.before(endDateDate)) {
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positions.add(getSatPos(trackDate))
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trackDate = Date(trackDate.time + incrementSeconds * 1000)
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fun getPositions(refDate: Date, stepSeconds: Int, minBefore: Int, minAfter: Int): List<SatPos> {
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val positions = mutableListOf<SatPos>()
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val endDate = Date(refDate.time + minAfter * 60L * 1000L)
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val startDate = Date(refDate.time - minBefore * 60L * 1000L)
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var currentDate = startDate
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while (currentDate.before(endDate)) {
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positions.add(getSatPos(currentDate))
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currentDate = Date(currentDate.time + stepSeconds * 1000)
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}
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return positions
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}
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fun getPasses(start: Date, hoursAhead: Int, windBack: Boolean): List<SatPassTime> {
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iterationCount = 0
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val satellite = SatelliteFactory.createSatellite(tle)
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val passes: MutableList<SatPassTime> = ArrayList()
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val trackEndDate = Date(start.time + hoursAhead * 60L * 60L * 1000L)
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var trackStartDate = start
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var windBackTime = windBack
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var lastAOS: Date
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fun getPasses(refDate: Date, hoursAhead: Int, windBack: Boolean): List<SatPassTime> {
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val passes = mutableListOf<SatPassTime>()
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val endDate = Date(refDate.time + hoursAhead * 60L * 60L * 1000L)
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var startDate = refDate
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var shouldWindBack = windBack
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var lastAosDate: Date
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var count = 0
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if (satellite.willBeSeen(qth)) {
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if (tle.isDeepspace) passes.add(nextGeoSatPass(start))
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else {
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if (satellite.tle.isDeepspace) {
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passes.add(nextDeepSpacePass(refDate))
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} else {
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do {
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if (count > 0) windBackTime = false
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val pass = nextSatPass(trackStartDate, windBackTime)
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lastAOS = pass.startTime
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if (count > 0) shouldWindBack = false
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val pass = nextNearEarthPass(startDate, shouldWindBack)
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lastAosDate = pass.startTime
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passes.add(pass)
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trackStartDate =
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Date(pass.endTime.time + threeQuarterOrbitMinutes() * 60L * 1000L)
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startDate = Date(pass.endTime.time + (oneQuarterOrbitMin * 3) * 60L * 1000L)
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count++
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} while (lastAOS < trackEndDate)
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} while (lastAosDate < endDate)
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}
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}
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return passes
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}
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private fun nextGeoSatPass(date: Date): SatPassTime {
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val aosAzimuth: Int
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val losAzimuth: Int
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val tca: Date
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val polePassed: String
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val cal = Calendar.getInstance(timeZone).apply {
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clear()
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timeInMillis = date.time
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}
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val satPos = getSatPos(cal.time)
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aosAzimuth = (satPos.azimuth / (2.0 * Math.PI) * 360.0).toInt()
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losAzimuth = (satPos.azimuth / (2.0 * Math.PI) * 360.0).toInt()
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tca = satPos.time
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polePassed = getPolePassed(satPos, satPos)
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cal.add(Calendar.HOUR, -12)
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val startDate = cal.time
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cal.add(Calendar.HOUR, 24)
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val endDate = cal.time
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return SatPassTime(
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startDate, endDate, tca, polePassed, aosAzimuth,
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losAzimuth, satPos.elevation / (2.0 * Math.PI) * 360.0
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)
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private fun nextDeepSpacePass(refDate: Date): SatPassTime {
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val satPos = getSatPos(refDate)
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val startDate = Date(refDate.time - 24 * 60L * 60L * 1000L)
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val endDate = Date(refDate.time + 24 * 60L * 60L * 1000L)
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val aosAzimuth = (satPos.azimuth / (2.0 * Math.PI) * 360.0).toInt()
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val losAzimuth = (satPos.azimuth / (2.0 * Math.PI) * 360.0).toInt()
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val maxEl = satPos.elevation / (2.0 * Math.PI) * 360.0
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return SatPassTime(startDate, endDate, polePassed, aosAzimuth, losAzimuth, maxEl)
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}
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private fun nextSatPass(date: Date, windBack: Boolean = false): SatPassTime {
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val aosAzimuth: Int
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val losAzimuth: Int
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private fun nextNearEarthPass(refDate: Date, windBack: Boolean = false): SatPassTime {
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val calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC")).apply {
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clear()
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timeInMillis = refDate.time
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}
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var maxElevation = 0.0
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var elevation: Double
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var prevPos: SatPos
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var polePassed = "none"
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// get the current position
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val cal = Calendar.getInstance(timeZone).apply {
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clear()
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timeInMillis = date.time
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}
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// wind back time 1/4 of an orbit
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if (windBack) {
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val meanMotion = tle.meanmo
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cal.add(Calendar.MINUTE, (-24.0 * 60.0 / meanMotion / 4.0).toInt())
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}
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var satPos = getSatPos(cal.time)
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if (windBack) calendar.add(Calendar.MINUTE, -oneQuarterOrbitMin)
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var satPos = getSatPos(calendar.time)
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// test for the elevation being above the horizon
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if (satPos.elevation > 0.0) {
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// move time forward in 30 second intervals until the sat goes below the horizon
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do {
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satPos = getPosition(cal, 60)
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calendar.add(Calendar.SECOND, 30)
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satPos = getSatPos(calendar.time)
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} while (satPos.elevation > 0.0)
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// move time forward 3/4 orbit
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cal.add(Calendar.MINUTE, threeQuarterOrbitMinutes())
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calendar.add(Calendar.MINUTE, oneQuarterOrbitMin * 3)
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}
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// now find the next time it comes above the horizon
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// find the next time it comes above the horizon
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do {
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satPos = getPosition(cal, 60)
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calendar.add(Calendar.SECOND, 60)
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satPos = getSatPos(calendar.time)
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elevation = satPos.elevation
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if (elevation > maxElevation) {
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maxElevation = elevation
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}
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if (elevation > maxElevation) maxElevation = elevation
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} while (satPos.elevation < 0.0)
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// refine it to 5 seconds
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cal.add(Calendar.SECOND, -60)
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// refine it to 3 seconds
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calendar.add(Calendar.SECOND, -60)
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do {
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satPos = getPosition(cal, 5)
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calendar.add(Calendar.SECOND, 3)
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satPos = getSatPos(calendar.time)
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elevation = satPos.elevation
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if (elevation > maxElevation) {
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maxElevation = elevation
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}
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prevPos = satPos
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if (elevation > maxElevation) maxElevation = elevation
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} while (satPos.elevation < 0.0)
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val startDate = satPos.time
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aosAzimuth = (satPos.azimuth / (2.0 * Math.PI) * 360.0).toInt()
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val aosAzimuth = (satPos.azimuth / (2.0 * Math.PI) * 360.0).toInt()
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// now find when it goes below
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do {
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satPos = getPosition(cal, 30)
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val currPolePassed = getPolePassed(prevPos, satPos)
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if (currPolePassed != "none") {
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polePassed = currPolePassed
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}
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calendar.add(Calendar.SECOND, 30)
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satPos = getSatPos(calendar.time)
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elevation = satPos.elevation
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if (elevation > maxElevation) {
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maxElevation = elevation
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}
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prevPos = satPos
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if (elevation > maxElevation) maxElevation = elevation
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} while (satPos.elevation > 0.0)
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// refine it to 5 seconds
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cal.add(Calendar.SECOND, -30)
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// refine it to 3 seconds
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calendar.add(Calendar.SECOND, -30)
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do {
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satPos = getPosition(cal, 5)
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calendar.add(Calendar.SECOND, 3)
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satPos = getSatPos(calendar.time)
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elevation = satPos.elevation
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if (elevation > maxElevation) {
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maxElevation = elevation
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}
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if (elevation > maxElevation) maxElevation = elevation
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} while (satPos.elevation > 0.0)
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val endDate = satPos.time
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losAzimuth = (satPos.azimuth / (2.0 * Math.PI) * 360.0).toInt()
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val tca = Date(startDate.time + (endDate.time - startDate.time) / 2)
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return SatPassTime(
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startDate, endDate, tca, polePassed, aosAzimuth,
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losAzimuth, maxElevation / (2.0 * Math.PI) * 360.0
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)
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}
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private fun getPosition(cal: Calendar, offSet: Int): SatPos {
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cal.add(Calendar.SECOND, offSet)
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return getSatPos(cal.time)
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}
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private fun getPolePassed(prevPos: SatPos, satPos: SatPos): String {
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var polePassed = "none"
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val north = "north"
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val south = "south"
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val az1 = Math.toDegrees(prevPos.azimuth)
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val az2 = Math.toDegrees(satPos.azimuth)
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if (az1 > az2) {
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if (az1 > 350 && az2 < 10) polePassed = north
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else if (az1 > 180 && az2 < 180) polePassed = south
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} else {
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if (az1 < 10 && az2 > 350) polePassed = north
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else if (az1 < 180 && az2 > 180) polePassed = south
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}
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return polePassed
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}
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private fun threeQuarterOrbitMinutes(): Int {
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return (24.0 * 60.0 / tle.meanmo * 0.75).toInt()
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val losAzimuth = (satPos.azimuth / (2.0 * Math.PI) * 360.0).toInt()
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val maxEl = maxElevation / (2.0 * Math.PI) * 360.0
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return SatPassTime(startDate, endDate, polePassed, aosAzimuth, losAzimuth, maxEl)
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}
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}
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Reference in new issue
Block a user