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satnow.py
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satnow.py
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#!/usr/bin/env python3
######################################################
# satnow.py - Calculate AZ, elevation and distance (in miles) between your QTH and one or more satellites RIGHT NOW
#
# HISTORICAL INFORMATION -
#
# 2022-03-07 msipin Created from the current version of satdist.py
# 2022-03-08 msipin Added satellite's current direction (rising/falling)
# Added display of next pass
# 2022-03-10 msipin Display next-event time as 1st output field on the line to allow sorting by next event
######################################################
# You need to install this Python3 library -
# sudo pip3 install skyfield
from skyfield.api import Topos, load, wgs84
import datetime
from datetime import timezone
from dateutil import tz
import sys
def DegreesToRadians(tDegrees):
return ((float(tDegrees) * math.pi) / 180.0)
def RadiansToDegrees(tRadians):
return ((float(tRadians) * 180.0) / math.pi)
def RadiansToNaticalMiles(tRadians):
return ((float(tRadians) * 10800.0 ) / math.pi) # 10800 = 180 * 60
def NaticalMilesToStatueMiles(tNaticalMiles):
return (float(tNaticalMiles) * 1.15)
def StatuteMilesToNaticalMiles(tStatueMiles):
return (float(tStatueMiles) / 1.15)
def StatuteMilesToKilometers(tStatueMiles):
return (float(tStatueMiles) * 1.609344)
#stations_url = 'http://celestrak.com/NORAD/elements/stations.txt'
#satellite = by_name['ISS (ZARYA)']
stations_url = "https://www.amsat.org/tle/current/nasabare.txt"
#satellite = by_name['AO-07']
satellites = load.tle_file(stations_url)
print('Loaded', len(satellites), 'satellites')
ts = load.timescale(builtin=True)
def gridCase(input):
A=''
B=''
C=''
D=''
E=''
F=''
if (len(input)>= 4):
chars = [char for char in input]
A=chars[0].upper() # Long
B=chars[1].upper() # Latt
C=chars[2] # Long
D=chars[3] # Latt
if (len(input)>= 6):
E=chars[4].lower() # Long
F=chars[5].lower() # Latt
if ((A >= 'A') and (A <= 'R') and (B >= 'A') and (B <= 'R')):
return(A+B+C+D+E+F)
return('?')
def gs2LatLon(input):
lat=0.0
lon=0.0
if (len(input)>= 4):
chars = [char for char in input]
A=chars[0] # Long
B=chars[1] # Latt
C=chars[2] # Long
D=chars[3] # Latt
if (len(input)>= 6):
E=chars[4] # Long
F=chars[5] # Latt
lon=getLon3(A,C,E)
lat=getLat3(B,D,F)
else:
lon=getLon2(A,C)
lat=getLat2(B,D)
return(lat,lon)
def getLon2(LoA,LoB):
return getLon3(LoA,LoB,'l')
def getLon3(LoA,LoB,LoC):
a=ord(LoA) - ord('A') # A - R (18 possibilities) 'I'/'J' = mid
a=a*20 # 20 degrees Lon each
b=ord(LoB) - ord('0') # 0 - 9 (10 possibilities) '4'/'5' = mid
b=b*2 # 2 degrees Lon each
c=ord(LoC) - ord('a') # a - x (24 possibilities) 'l'/'m' = mid
#c=(c*5)/60 # 5 minutes Lon each
c=(c/12)+(1/24) # FROM WEBSITE - ISN'T EXPLAINED
Lon=a+b+c-180.0
#print("Longitude: ", Lon)
return Lon
def getLat2(LaA,LaB):
return getLat3(LaA,LaB,'l')
def getLat3(LaA,LaB,LaC):
d=ord(LaA) - ord('A')
d=d*10 # 10 degrees Lat each
e=ord(LaB) - ord('0')
e=e*1 # 1 degree Lat each (no adjustment needed)
f=ord(LaC) - ord('a')
#f=(f*2.5)/60 # 2.5 minutes Lat each
f=(f/24)+(1/48) # FROM WEBSITE - ISN'T EXPLAINED
Lat=d+e+f-90.0
#print("Latitude: ",Lat)
return Lat
def printHeading(sat,az,el,distance,indicator,t0,tz):
# Display time/data
tx_local = t0.astimezone(tz).strftime("%Y-%m-%d %H:%M:%S")
print(tx_local,"Local /",t0.utc_strftime('%Y-%m-%d %H:%M:%S'), "UTC", "-", end=' ')
print("%-15s" % sat, end=indicator)
#print("DEBUG: AZ - ",dir(az))
print(' AZ: %3d' % int(az.degrees),end='')
#print("DEBUG: EL - ",dir(el))
print(' EL: %3d' % int(el.degrees),end='')
print(' Dist: {:5.0f} mi'.format(distance.km * 0.621371),end=' ')
numargs = len(sys.argv)
if (numargs < 3):
print("\nusage: %s <ground-station-gridsquare> <TLE-file_name_of_satellite_1> [ ... <TLE-file_name_of_satellite_n> ]\n" % sys.argv[0])
sys.exit(1)
# This command is argument[0]
# Establish the minimum elevation
satarg=2
min_el = 12.0 # Default, unless specified on cmdline
# Gridsquare is argument[satarg-1]
# DM14
#Pos1="DM14hl"
Pos1=gridCase(sys.argv[satarg-1])
print("Pos: ",gridCase(Pos1))
Lat1=0.0
Lon1=0.0
if (len(Pos1) >= 4):
##print("\n")
Lat1,Lon1 = gs2LatLon(Pos1)
print("Longitude1: ", Lon1)
ew1='E'
if (Lon1 < 0.0):
ew1='W'
##Lon1 = Lon1 * (-1.000)
print("E/W: ", ew1)
print("Latitude1: ", Lat1)
ns1='N'
if (Lat1 < 0.0):
ns1='S'
##Lat1 = Lat1 * (-1.000)
print("N/S: ", ns1)
print("")
# Start time (now) -
now = datetime.datetime.now(timezone.utc)
t0 = ts.utc(now)
##print(t0)
# Establish time "a few seconds ago"
# Use 30-seconds (aka a half-a-minute) (0.5 of (24 hrs * 60 minutes))
ti_increment = (0.5/(24*60))
# Decrement time from "now"
t1 = t0 - ti_increment
##print(t1)
# Get local timezone
tz = tz.tzlocal()
print("Current time:",t0.utc_strftime('%Y-%m-%d %H:%M:%S'), "UTC")
tilocal = t0.astimezone(tz).strftime("%Y-%m-%d %H:%M:%S")
print("Current time:",tilocal,"Local")
print()
qth = wgs84.latlon(Lat1, Lon1)
# Satellite name(s) are arguments[2+]
for i in range(satarg,numargs):
sat = sys.argv[i]
##print("\nSat: ",sat)
by_name = {sat.name: sat for sat in satellites}
#satellite = by_name['ISS (ZARYA)']
satellite = by_name[sat]
##print(satellite)
difference = satellite - qth
# Find az/el "a few seconds ago"
topocentric = difference.at(t1)
old_el, old_az, old_distance = topocentric.altaz()
# Find az/el right now
topocentric = difference.at(t0)
now_el, now_az, now_distance = topocentric.altaz()
print('\n\tDEBUG: now_EL: %3d' % int(now_el.degrees))
# Develop indicator of satellite's motion
indicator=' ? ' # Unknown
if (now_el.degrees > old_el.degrees):
indicator=' + ' # Rising
if (now_el.degrees < old_el.degrees):
indicator=' - ' # Falling
if (now_el.degrees == old_el.degrees):
indicator=' = ' # Stable
# Identifies whether a successful pass was computed
printed_heading=0
# If satellite is currently above the horizon, print its heading (using the current time)
if (now_el.degrees >= 0.0):
printHeading(sat,now_az,now_el,now_distance,indicator,t0,tz)
# Remember we've already printed this satellite's heading
printed_heading = 1
# Compute next pass
ti_aos=t0
ti_los=t0
t, events = satellite.find_events(qth, t0, (t0 + 7), altitude_degrees=0.9)
for ti, event in zip(t, events):
# Find az/el at this event
topocentric = difference.at(ti)
el, az, distance = topocentric.altaz()
# AOS = acquisition of signal, MAX = maximum elevation, LOS = loss of signal
name = ('AOS', 'MAX', 'LOS')[event]
tx_local = ti.astimezone(tz).strftime("%Y-%m-%d %H:%M:%S")
mins = int((ti - t0)*(24*60))
hrs = int(mins/60.0)
mins = (mins - (hrs*60))
if (name == "AOS"):
ti_aos = ti
#print(" | Next AOS - ",tx_local,"/",ti.utc_strftime('%Y-%m-%d %H:%M:%S'), "UTC", "-", end=' ')
#print(tx_local,"/",ti.utc_strftime('%Y-%m-%d %H:%M:%S'), "UTC", "- AOS -", end=' ')
#print(" | Next AOS - ",tx_local, end=' ')
#print(" | Next AOS - ",int((ti - t0)*(24*60)),"mins", end=' ')
if (printed_heading == 0):
printHeading(sat,now_az,now_el,now_distance,indicator,ti_aos,tz)
printed_heading = 1
print("| AOS in",end=' ')
if (hrs > 0):
print("%dh" % hrs,end=' ')
if (mins >= 1.0):
print("%dm" % mins, end=' ')
else:
print("%ds" % int(mins * 60), end=' ')
if (name == "MAX"):
print('| MAX %d deg' % int(el.degrees),end=' ')
#print(tx_local,"/",ti.utc_strftime('%Y-%m-%d %H:%M:%S'), "UTC", "-", end=' ')
#print(tx_local, end=' ')
if (name == "LOS"):
ti_los = ti
mins = int((ti_los - ti_aos)*(24*60))
hrs = int(mins/60.0)
mins = (mins - (hrs*60))
#print(" | Next LOS - ",tx_local,"/",ti.utc_strftime('%Y-%m-%d %H:%M:%S'), "UTC")
#print("| LOS:",tx_local)
#print("| LOS after",end=' ')
print("|",end=' ')
if (hrs > 0):
print("%d hr" % hrs,end=' ')
if (mins >= 1.0):
print("%d min" % mins, end=' ')
else:
print("%d sec" % int(mins * 60), end=' ')
print("pass",end='')
break
# If this satellite didn't cross our sky (as indicated by NO-AOS-FOUND) then display where
# it currently is, anyway
if (printed_heading == 0):
printHeading(sat,now_az,now_el,now_distance,indicator,t0,tz)
printed_heading = 1
print("")
print()
sys.exit(0)