Inserting Live Tracks Into APRS

Scripts

These scripts were created to route non-aprs telemetry from a high altitude balloon into the aprs-is system. The balloon these were created for had an aprs, spot, and cellular tracking system.

To insert the tracking data into the APRS-IS system you need to run the script on a computer with an Internet connection. The scripts are very Alpha and will most likely break if they encounter anything unexpected. I am also a little embarrassed about my code, it's not very elegant.

Spot

#!/usr/bin/perl
# GPLv3 Matt Skorina May 2011
# Converts SPOT Tracker position to APRS format and sends it to APRS-IS.
# Make sure you clear previous tracks before starting.
# Currently this will not work if there is only 1 entry in the XML feed
# http://www.nntp.perl.org/group/perl.beginners/2007/04/msg90658.html
# says the only solution is to check, or to not use XML::Simple.
# Also we can just leave some enteries in the XML feed and the latest
# will be beaconed to APRS when the script is started, which would
# probably be okay
$spot_id = "<SPOT API KEY>"; # Shared key for SPOT device
$check_interval = 60; # How often to check for new data (seconds)
$spot_callsign = "KF7DXI-12"; # Callsign of beacon
$spot_symbol = "/I"; # /I = TCPIP Internet Station
$software = "SPOT01"; # Digipath for SPOT position
$comment = "*TESTING* SPOT Tracker"; # Comment for message in addition to time stamp
use LWP::Simple;
use XML::Simple;
use Ham::APRS::FAP;
use IO::Socket;
$last_packet = "";
$spot_url = "http://share.findmespot.com/messageService/guestlinkservlet?glId=$spot_id&completeXml=true";
while(1==1) {
$spot_data = get($spot_url);
$xml = new XML::Simple;
$spot_xml = $xml->XMLin("$spot_data");
print @spot_xml;
if ($spot_xml->{totalCount} != 0) {
$latitude = "$spot_xml->{message}->[0]->{latitude}";
$longitude = "$spot_xml->{message}->[0]->{longitude}";
$time = "$spot_xml->{message}->[0]->{timeInGMTSecond}";
$timestamp = Ham::APRS::FAP::make_timestamp($time,0);
$position = Ham::APRS::FAP::make_position($latitude,$longitude,-1,0,-10000,$spot_symbol,0,0);
$packet = "$spot_callsign>$software,TCPIP*:=$position$timestamp $comment";
if ($packet ne $last_packet) {
print "$packet\n";
my $sock = new IO::Socket::INET (
PeerAddr => '64.89.177.168',
PeerPort => '14580',
Proto => 'tcp',
);
die "Could not connect to server: $!\n" unless $sock;
print $sock "user KF7DXI-2 pass 22441\n";
print $sock "$packet\n";
close($sock);
$last_packet = $packet;
}
}
sleep($check_interval);
print "Done\n";
}

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Instamapper

#!/usr/bin/perl
# GPLv3 Matt Skorina May 2011
# This script will scrape the API of the Instamapper (instamapper.com)
# cellular tracking service and send position reports to APRS-IS to be
# collected by any APRS internet connected client.
# Make sure you clear previous tracks before starting.
# Running a test for several hours we had the script fail after awhile
# with an error of "malformed JSON string, neither array, object,..."
# which failed on the "$decode = decode_json($raw);" line
# I don't know the input that caused the error but we need the script to
# keep going in the event of non-parasable errors because we can't
# restart it in the field. Or we need to be able to restart it in the
# field.
$api_key = "<INSTAMAPPER API KEY>";
$check_interval = 5; # How long to wait between checks, minimum per API terms is 10s
$igate = "<VAID CALLSIGN>"; # Callsign to gate packet to APRS-IS
$pass = "<APRS PASSCODE>"; # APRS passcode for igate callsign (passcode CALLSIGN on *nix systems)
$aprs_server = "64.89.177.168"; # APRS-IS server to connect to
$aprs_port = "14580"; # Port of APRS-IS server normally 14580
$callsign = "<VALID CALLSIGN>"; # Callsign for cellular tracker
$software = "INSTAM"; # What type of device this is
$symbol = "/I"; # APRS symbol, /I is TCPIP
$comment = "Balloon Cell Tracker"; # APRS comment, so people know what this is
use LWP::Simple;
use JSON;
use Ham::APRS::FAP;
use IO::Socket;
$last_packet = "";
$url = "http://www.instamapper.com/api?action=getPositions&key=$api_key&format=json";
while (1==1) { # There is probably a better way to do this...
$raw = get($url);
$decode = decode_json($raw);
$latitude = $decode->{positions}->[0]->{latitude};
$longitude = $decode->{positions}->[0]->{longitude};
$altitude = $decode->{positions}->[0]->{altitude};
$speed_meter = $decode->{positions}->[0]->{speed}; # Instamapper gives speed in m/s
$speed_kph = $speed_meter*3.6; # APRS wants speed in kph
$course = $decode->{positions}->[0]->{heading};
$time = $decode->{positions}->[0]->{timestamp};
$timestamp = Ham::APRS::FAP::make_timestamp($time,0); # To double check time, probably a better way to do this
$position = Ham::APRS::FAP::make_position($latitude,$longitude,$speed_kph,$course,$altitude,$symbol,0,0);
$packet = "$callsign>$software,TCPIP*:=$position$timestamp $comment";
if ($packet ne $last_packet) {
print "$packet\n"; # So you can see what's going on
$sock = new IO::Socket::INET ( # One time connection to server for each packet
PeerAddr => "$aprs_server",
PeerPort => "$aprs_port",
Proto => "tcp",
);
die "Could not connect to server\n" unless $sock;
print $sock "user $igate pass $pass\n";
print $sock "$packet\n";
close($sock);
$last_packet = $packet; # So we don't send duplicate packets
}
sleep($check_interval); # So we don't swamp the API
print "Done\n";
}

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About

Matt Skorina is a freshman Electrical Engineering student. more...

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