APRS tracker

import aprslib
import location
import time
from math import sin, cos, sqrt, atan2, radians

last = None
count = 0

location.start_updates()

aprs = aprslib.IS('CALLSIGN',aprslib.passcode('CALLSIGN'))
aprs.connect()
packet = aprslib.packets.PositionReport()
packet.fromcall='CALLSIGN'  #Insert your hamradio call sign
packet.tocall='WIDE1'
packet.comment=' '
packet.symbol='>'

def dist(locA,locB):
    lat1 = radians(locA['latitude'])
    lon1 = radians(locA['longitude'])
    lat2 = radians(locB['latitude'])
    lon2 = radians(locB['longitude'])

    dlon = lon2 - lon1
    dlat = lat2 - lat1

    a = sin(dlat / 2.0)**2.0 + cos(lat1) * cos(lat2) * sin(dlon / 2.0)**2.0
    c = 2.0 * atan2(sqrt(a), sqrt(1.0 - a))

    return 6373.0 * c * 0.621371
    
def sendLoc(aprs,loc):
    packet.timestamp=loc['timestamp']
    packet.latitude=loc['latitude']
    packet.longitude=loc['longitude']
    aprs.sendall(packet)
    
    print 'Location Updated!'
    
    
def course(last,loc):
    old = last['course']
    new = loc['course']
    if old <0:
        return False
    if new < 0:
        return False
    delta = abs(new-old)
    if delta <= 180:
        delta = delta
    else:
        delta= 360-delta
    if delta > 60:
        print 'Course Changed!',new,old,delta
        return True
        
loc = location.get_location()
sendLoc(aprs,loc)
last=loc
while True:
    loc = location.get_location()
    if (dist(last,loc) > 0.25 and count >= 4) or dist(last,loc) > 1 or count >24 or course(last,loc):
        count = 0
        last=loc
        try:
            sendLoc(aprs,loc)
        except:
            aprs.connect()
            sendLoc(aprs,loc)
    else:
        count +=1
    time.sleep(10