Thursday, August 30, 2007

APRS balloon flights this weekend

Mark, N4CMB reports in a blog comment that members of the North Texas Balloon Project are launching flight 15 on Saturday, September 1, 2007 at about 13:30 UTC (8:30 am CDT) from the Hillsboro Municipal Airport (32.0835N 97.0971W). The balloon's APRS tracker callsign is W5SJZ-11. It will carry beacons and a crossband FM repeater. Thanks for the note, Mark!

Ilmari-2007b will fly on Sunday, September 2, 2007 at about 06:00 UTC (09:00 EET+DST) from Sappee, KP21GJ. It's APRS tracker callsign is OH2SIX-11. In addition to the beacons Ilmari carries a crossband linear transponder (much like a satellite: it receives on 144 MHz and transmits on 437 MHz) and an 1282 MHz FM-ATV video transmitter.

Update (Monday 3rd of September): Ilmari 2007b was postponed due to bad weather, but NTBP flight 15 did fly on saturday.

Happy tracking, everyone!

Sunday, August 26, 2007

Searching APRS and AIS targets using wildcards

I've finally added wildcard character support for searching stations in the map and info views. A wildcard search in either will return a list of stations (together with their symbols, report ages and comment strings). Clicking on a station in the list will jump to the map or info view of the given station. To limit load on the server, a maximum of 300 stations will be shown.

Supported wildcard characters are ? (any single character) and * (any number of characters).
After successfully looking up a callsign in either the info or map views, links will be shown to other SSIDs of the same callsign (if there are any).

Wednesday, August 22, 2007

10 MHz HF APRS in Namibia

Mike OE3MZC, who happens to be the president of the Austrian Amateur Radio Society, is staying in Namibia as V51/OE3MZC, and driving around in a 4-wheel-drive car featuring a 10 MHz HF APRS tracker. His position reports are received by igates in South Africa (1500 km away) and Australia (11000 km, or 7000 miles away)!
I suddenly feel like setting up an 10 MHz igate somewhere.

(found this on the South African Radio League web forum.)

Monday, August 20, 2007

Gliders in Sweden

APRS trackers have been installed in a bunch of gliders (or sailplanes) in Sweden. They seem to fly around Eskilstuna, and belong to Eskilstuna Flygklubb. Their APRS callsigns follow the callsigns of the airplanes, with the "-" removed (APRS callsign SEUUU belongs to the SE-UUU aircraft). I wonder what frequency they're using, and if they're doing this with an amateur license... but it's very cool indeed.
And the list goes on...

I'm sure a good busy flying day looks very cool on Google Earth.

AIS ship tracking

AIS, or Automatic Identification System is not much unlike APRS - it is a professional tracking system for ships. It runs at 9600 bit/s (GMSK) on two marine VHF frequencies, with a nice binary protocol which features automatic synchronization and time multiplexing - even with a very high number of vessels transmitting position reports once every 2 to 10 seconds, packet collisions will not be a problem. The protocol is standardized and well-defined, but unfortunately patented.

Fortunately the protocol is unencrypted and available. There is a Windows application called ShipPlotter which can decode AIS traffic and export the received position reports using HTTP. If you live somewhere near a coast, set up a 160 MHz FM receiver with a discriminator output or data port (you can't properly decode 9600 bit/s from the audio output of most FM receivers), plug it in the sound card of your PC, and you can track ships from miles away. A single receiver on the south coast of Finland can hear ships from Tallinn and a good part of the Gulf of Finland.

Now, can receive the HTTP position report exports sent by ShipPlotter. If you run it somewhere on a 24/7 basis, please get in touch with me and share the view with others! There's currently one receiver feeding us with AIS traffic from Helsinki, Gulf of Finland (thanks Tapio!).

To see some AIS traffic, zoom to the area between Helsinki, Finland and Tallinn, Estonia and make sure you have enabled viewing AIS data in the Options!

High-altitude balloons

There are groups of hams flying weather balloons stuffed with APRS trackers, digital cameras, repeaters and linear transponders, and other cool stuff. These things are cheaper to build and fly than self-built satellites, but offer a lot of the same features and thrill. I'm aware of two projects which flew during the past couple weeks.

Ilmari-2007 (OH2SIX-12) flew in Finland on 11th of August 2007 and is planned to fly again on 2nd of September. It's equipped with a linear transponder (70cm to 2M, just like amateur satellites - actually the device was designed for a future satellite), a couple of beacons, an APRS tracker transmitting on 437 MHz, a couple of temperature sensors, and an 1.2 GHz Amateur Television (ATV) transmitter sending live video from the heights! The first flight went up to about 30 km (100 000 feet). Here are the links (sorry for the login requirement):

- The track of the first Ilmari-2007 flight
- Current location of Ilmari-2007 - use this link on 2nd of September to follow the flight in real time. The flight is scheduled at 06:00 UTC (but they usually fly late).

SABLE-3 (VA6TNY-11) also flew on 11th of August, in South Alberta, Canada. It was equipped with a 8-megapixel digital still camera taking crisp pictures once every minute, and an APRS tracker. It flew up to 117,597 feet (over 35 km), and took some really nice photos!

- The track of the SABLE-3 flight on 11th of August, 2007

These balloon flights took usage to an all-time high - there were over 100 simultaenous users tracking the balloons alone.

If you are planning to launch a balloon, please share the fun and drop me an email, or post a comment on this blog. Thanks!

My first little blog post.

Hi, and welcome to my very first blog, and it's very first posting. I intend to use this space to ramble about new features and bugs found at - my little APRS web database project, which got a little out of hand. I don't feel like implementing a nice news feature on the site itself right now, so I'll just use Blogger for now!

I'll also try to drop links to interesting locations and attractions found in the APRS world. Feel free to mail me if you spot something interesting. Thanks!

- Hessu, OH7LZB