Dead reckoning and radio horizon circles

This large passenger boat is actually
making some turns between the islands.

Today aprs.fi got a simple implementation of dead reckoning. Moving stations which have announced their position, speed and course within the past 30 minutes will show a blue line extending from the latest announced position. The line indicates where the station would be right now if it proceeded on that course at exactly the same speed.

To limit the performance impact of this feature the DR indicator will be shown for a single station at a time. Click on a station to enable it. It's also enabled automatically for a tracked station.

Naturally it'll show some rather bogus estimations for vehicles which have stopped moving but have not transmitted a new packet with a speed of 0. Most trackers installed in cars loose their power input before they have a chance of transmitting a packet at the parking spot.

A plane flying at 2648 feet, and the digipeaters
and igates which have received it.

Flying stations having a "flying" symbol such as airplane or balloon will have two circles drawn around them. A larger blue circle indicates the sea-level horizon from the current altitude of the station. A smaller green circle indicates the area where the station can be seen at an elevation larger than 5 degrees.

The circles are useful for estimating the distance at which the station can be heard, which can be of use for tracking teams of high-altitude balloons. It also gives pilots an idea of the large amount of digipeaters and igates in range.

The circles are drawn for stations having a suitable symbol when the altitude is over 100 meters. Other stations will also get the circles when their altitude reaches 1000 meters.

aprs.fi upgrade on Monday 2012-03-19

aprs.fi will be upgraded on Monday 2012-03-19. Some downtime should be expected, starting around 9 AM local time (0700 UTC). If you can find some bugs in beta.aprs.fi, this is the time to report and get them fixed before they make their way to aprs.fi! Here's the long list of changes included in the upgrade. It's so long that, as usual, some new bugs will probably pop up. Please report them on the discussion group and I'll try to get them fixed right away.

Anchor navigation and more AJAX

Achilles (left) and Ajax (right) play a board game with
knucklebones on this late 6th-century lekythos, a type of
oil-storing vessel associated with funeral rites. Photo taken
in Musée du Louvre by Marie-Lan Nguyen, 2011
(CC by attribution, Wikipedia/Wikimedia).

The technical implementation of the navigation in the real-time map has been completely changed. In the new model the map page is not reloaded from the servers and initialized again from scratch every time an user changes the view by searching for a new callsign or an address. This AJAX magic will make callsign searches and other view modifications considerably faster, especially on slow computers and slow connections such as mobile devices. It'll also reduce load on my and Google's servers. And make the browser's bookmark functions and the back button work better than before.

All of the links used by aprs.fi to refer to specific map views have changed, but the traditional ones documented on the linking instructions page will keep working, and I encourage you to use them as before - they're not going anywhere.

Try searching for OH2K and OH2TI one by one again and again, and you'll notice both the improved loading speed, and a nice panning effect. It'll pan whenever the newly searched station is close enough to the current view.

Improved address search

Address search has been improved to make a better use of the data returned by Google's API. A marker for the result is now only shown if the result is accurate (such as a street, or a house number on a specific street).

Address search will also adjust the zoom level - "Finland" or "Pohjois-Karjala" or "USA" should actually fit the specified region in view. The zoom levels come from Google and I can not make it any smarter than that (yes, "USA" will zoom out a bit too much). But it's certainly better than it was (fixed zoom level after address search).

Improved response times

When you make changes to the real-time map view, for example by zooming out or selecting a time range, aprs.fi will now react much more quickly.

New time range back/forward buttons

When a station is tracked, there are now two new handy additional arrow buttons to jump the time range back and forward. If you have selected an arbitrary range, it will jump the same amount back (select a week, and it'll jump to the previous week). Otherwise it'll select the current whole day (UTC 00:00:00 to 23:59:59 - sorry, no local time support yet) on the first click, and the following clicks will jump by 24 hours.

Sharper map graphics on iPad/iPhone

The scaling of the web page was tuned to switch automatically so that map graphics are not blurred on the iOS devices, especially when the device switches between landscape and portrait orientation.

Other small things

Searching for "OH2RDK" will now give a proper "there are other SSIDs available although this one doesn't exist" response.

aprs.fi now uses a new version of the Google Maps API, bringing in some visual updates and speedups from Google.

An old bug which makes stations disappear after a quick zoom-in-and-back-out operation (and some other cases) has been fixed.

The "street view is off by 200 meters" bug is fixed. Also, the map should stay centered when Street View is enabled or disabled.

The ruler tool now displays distances shorter than 1 km in meters to allow measuring short distances.

When a station is tracked on a mobile device, the info balloon does not automatically pop up and block the whole view.

Raw packets view in decoded mode displays the position packet's type (compressed, mic-e...).

Tuned digipeater/igate "heard" map to collect more data and leave less gaps in the map.

Support for new major version of the database server (SQL syntax changes).

CSRF security fixes were implemented in many places.

Some rough corners have been rounded up (literally), and a few shadows have been cast (again, literally).

Does aprs.fi feel slow?

Be sure to try it with a modern, quick browser such as Google Chrome, Safari or Internet Explorer 9. If you're upgrading from Firefox or an older Internet Explorer, you'll be surprised by the difference it makes.

Data collection outage on Sunday, 2011-01-29

aprs.fi data collection was down today (2011-01-29) between 14.20 and 14.55 UTC due to a hardware failure. After finishing my dinner I moved the master service to another server and things appear to be working properly now.


Sorry for the trouble!

aprs.fi closed in U.S. on Wednesday

aprs.fi will join Wikipedia and Reddit, and protest the proposed U.S. SOPA/PROTECT-IP legislation by closing down on Wednesday. (News about Reddit blackout, and Wikipedia joining it.)

The aprs.fi outage will only affect clients in the United States (or those with IP address mapping an U.S. network operator - the targeting is not fully accurate).

Although the law is being made in the U.S., it will break the Internet on a global scale by making sites such as aprs.fi liable for links and content posted by the users of the site. Sites like aprs.fi are commonly run by individual developers or small volunteer teams. Due to the huge volume of automatically published user-generated content (50 packets per second currently!) it would be impossible for me to go through it all before publishing. If some APRS user would post links to copyright-infringing material, even when that material would reside somewhere else than aprs.fi itself, aprs.fi could be shut down in the U.S. and there would not be much that I could do about it. See how difficult it was for a falsely censored music blog to get unblocked under the current legislation.

The law claims to be targeted at pirate web sites, but it won't have any practical effect on criminal file sharing, since those networks can very easily switch to new domain names and IP addresses, or bypass the DNS altogether with modern peer-to-peer technologies. Instead, it will force web site administrators such as myself to pre-censor data (by, for example, removing user-posted links completely). In practice: no home page link shown with your APRS station on aprs.fi. This is just silly – on other sites which depend more on linking out it could ruin the whole show.

If you're an U.S. citizen, you can probably do something about this that would actually make a difference. I'm not there, so I can't (but I voted yesterday evening in Finland's presidential election!). Please read through the material on the Reddit blackout page, there are good "Learn More" and "Get Involved" sections in the end!

Data collection will be running as usual, so Wednesday's data will be available on Thursday.

Now I'm really happy that aprs.fi is aprs.fi instead of aprs.com or aprs.net. And that I'm not living in the UK. The really bad news is that similar laws are being pushed in Europe.

PS. You can get your APRS location from http://www.findu.com/cgi-bin/find.cgi?YOURCALL or DB0ANF. If a life-threatening disaster would happen in the U.S. let me know and I'll open up the site.

K6RPT-11 APRS balloon from California in Europe - igates needed for 144.390!

Updated 2011-12-14: Still flying, igates needed further west!

An APRS-equipped high-altitude balloon, using the callsign K6RPT-11 (track on aprs.fi), launched from San Jose, California, has almost crossed the Atlantic Ocean, and is now passing Azores, and approaching North Africa. With a little change in direction it could as well go to Spain or Portugal! It was already a great success when it managed to travel to the east coast of the US.

There is a catch - it's transmitting on the US frequency of 144.390 MHz instead of the usual European frequency of 144.800 MHz. That's will help reception, since 144.390 is very quiet around here, but we need some igates in Morocco, Spain, southern France, Italy, Greece, Turkey, and so on, to temporarily switch frequencies - and do it now! Keep an eye on the track - it could be coming your way!

Please help spread the word, right now, tonight, amongst igate operators around that area.

There might be a very fun recovery operation ahead for some hams down there.

Stephen H. Smith wrote:
"The K6RPT-1 APRS-equipped high-altitude balloon left the U.S. mainland,  headed out over the Atlantic about 0330 UTC Tuesday after a coast-to-coast crossing of the US from the San Jose, California launch site.

Radio contact was lost about 400 miles off the New Jersey coast. At that point it was still transmitting and reporting normal battery voltage, holding altitude around 107,000 ft, and headed toward the Straights of Gibraltar at about 150 MPH (240 KM/h)."

"It's now around sunset at it's current location, so it looks as though the balloon's envelope survived the day's UV exposure -- better and better chance now it WILL make landfall over there. ."

Links:

http://twitter.com/k6rpt (Balloon project's twitter feed)
http://www.californianearspaceproject.com/

APRS-IS packet loss on 2011-11-21

As seen in the statistic graphs, aprs.fi was only receiving about 60% of the APRS packets from the APRS-IS between 2011-11-20 23:40:40 UTC and 2011-11-21 08:25:57 UTC. During this time it was connected to a core server which apparently is not getting a full APRS-IS packet feed for some reason. As  a visible result the packets of about 40% of APRS stations did not get to aprs.fi.

The core server operator has been notified and aprs.fi is connected to another server again. Sorry for the trouble.

Using aprs.fi for SAR, ARES or other public service work? Let me know!

I know some of you use aprs.fi while doing volunteer search-and-rescue operations, ARES or other public service work.

If you wish to keep doing so as before, with the convenience of Google Maps, I need you to tell me and everyone else about your use. In writing. Please.

Put up a blog post or write about it on your volunteer organisation's web page. Send me an email pointing to the document. Write about what you are doing, where, when, and how aprs.fi is useful in what you do. Practical examples of real events are probably most useful.

This is important, since Google is going to start charging for the usage of their Maps API, which until now has been free for sites which are open and free to use (like aprs.fi). 

The charging is based on the amount of map loads. aprs.fi currently opens up the real-time map almost 42,000 times per day (when nothing special  happens). According to the new Google Maps terms, up to 25,000 map loads  per day is free, the rest will cost $4 per 1000 map loads. That amounts up to $68 per day, $2040 per month for me. No, I don't make that much from the advertisements. And there are some other costs involved in running such a site too (computer hardware, hosting, domain names, programming beer, to name a few).

"We will then start billing excess usage to your credit card when we begin enforcing the usage limits in early 2012." (the blog post)

The only real options seem to switching away from Google Maps to something else, or getting aprs.fi to qualify as being "in the public interest":

"Non-profits and applications deemed in the public interest (as determined by Google at its discretion) are not subject to these usage limits. For example, a disaster relief map is not subject to the usage limits even if it has been developed and/or is hosted by a commercial entity." (FAQ)

A lot of you will probably suggest switching to OSM. This is one option, but it has a few drawbacks:

• Address/place search isn't as good
• No  Street View, worse Satellite view, no Terrain view
• Less coverage in the countryside
• Takes a lot of work from me to switch from Google's API to OSM's API (aprs.fi uses the Google Maps API for a lot of things, like drawing lines & circles and placing car symbols on the map and presenting menus and pop-up balloons)
• OSM's map tile servers can't take the load - Lynn just got a note from OSM folks that APRSISCE/32 should make "other arrangements" and not download the maps directly from OSM. I would expect aprs.fi to generate even more load, and I'd probably have to run my own map server (which would take a significant amount of work and money, and it'd be much slower than Google's map servers).

This, and other options, are discussed on the aprs.fi discussion group.

So, I'll have to try to get in the "public interest" category. It might help if you could document your real usage in "disaster relief" and other public service work in writing. You can find my email address from the blogger profile (on the right side, scroll down to "about me", view my complete profile, contact, email).

Thank you!