aprs.fi within iOS 7 Safari web browser

When opening aprs.fi using the iOS 7 Safari browser on an iPad Mini, the browser is quite consistently killed by the operating system due to an out-of-memory situation, especially if there are a lot of stations in your area to show. This looks pretty much like the browser crashed, but the device's console log displays the OOM errors quite nicely. The same happens when I try to use Chrome. It worked pretty fine on iOS 6 on the same device.

It seems to me that iOS 7 grabs more memory itself, leaving less memory available for the applications, and the devices with 512 MB memory (or less) don't have enough to load aprs.fi in the browser when a lot of stations are brought to view. iPad Mini and iPad 2 have 512 megabytes, the original iPad 1 has 256 MB, the 3rd- and 4th-generation iPads ("new iPad") have 1 GB (specifications).

Sep 22 19:53:51 Minipad MobileSafari[1407] : Received memory warning.
Sep 22 19:53:53 Minipad MobileSafari[1407] : Received memory warning.
Sep 22 19:53:54 Minipad com.apple.launchd[1] (UIKitApplication:com.apple.mobilesafari[0xe421][1407]) : (UIKitApplication:com.apple.mobilesafari[0xe421]) Exited: Killed: 9

The same probably applies to iPhones, but I didn't upgrade to 7 yet.

There's not much I can do about this, other than make it somehow load less stations and lines on the map initially.

Or release a native iOS application which doesn't process the map data in Javascript, and will be able to keep its memory use lower that way.

Google Latitude support on aprs.fi

It's now possible to upload your position to aprs.fi from Google Latitude. Latitude, in turn, supports uploading position from a large number of mobile devices (Android, iPhone, Blackberry, Nokia/Symbian, Windows Mobile) using Google's Maps and Latitude applications.

See the user guide section on Google Latitude support for instructions.

If you don't see your position immediately on aprs.fi, please wait for a few minutes, and check if Google Latitude has your position on it's own web site. If it isn't shown there, the problem lies with your mobile application's configuration or lack of accurate position information on the phone. aprs.fi currently rejects positions with an accuracy that is worse than 4000 meters.

The web stations page in the user guide is a new thing, too. In addition to Latitude support, it documents the manual updating (point-and-click) and Geolocation API (web browser with GPS support on a mobile device) methods for position updating.

Feedback welcome, as usual!

iPad location sharing, bugfixes and Android support

I've installed a couple of fixes in the web locations updating code now. It failed to work for about 6 unlucky users due to a little bug which didn't take database replication delays into account. But that's sorted now.

I've also put the 'share location' button on the non-mobile site, so that it can be used on the iPad and other larger devices with GPS. We'll see what effect that has!

The good news is that it seems to work on several Android phones:

• Google Nexus One
• HTC Dream
• HTC Espresso
• Samsung Galaxy S
• Motorola Droid
• LG Ally

It'll probably work on the rest of the new ones with GPS, too.
The new tool buttons are now documented in the manual.

Web location uploads, better iPhone support, and favourite stations

I've just installed a rather large upgrade on the production aprs.fi servers. As usual, some things might break, in which case you'll get to keep both pieces, but it should be worth it.

The system now supports uploading positions directly to aprs.fi using a web browser which supports the W3C Geolocation API. In practice this means that you can update your location using a mobile phone which has a GPS and a modern web browser. No native application or purchase is required. I have only tested this with the iPhone (OS 3.0 and newer), but there is a good chance that Android phones will work, too. To try this out, create an user account on aprs.fi, log in from the phone, and click on the transmitting tower button to upload your position.

You can also click on the crosshair button to center the map on your current GPS coordinates. Naturally, your web browser will ask you whether your position can be revealed to aprs.fi before either of these functions are enabled.

The positions are not transmitted to or via the APRS-IS, so it is OK for users without amateur radio licenses to upload their positions, too. The stations are identified as web stations on aprs.fi, for example: oh7lzb föni (my iPhone). Web stations names are not restricted by AX.25 / APRS limitations, and can contain spaces and international characters.

The names of the web stations live in a separate namespace from APRS and AIS stations. There can be a 'N0CALL' phone as well as a 'N0CALL' APRS station, and a 'N0CALL' AIS ship. When names overlap, the web site will let you pick the right station from a list. Multiple web stations may also share the same name, which should help avoid collisions.

The mobile version of the map has been improved to better support the iPhone. With some luck, these improvements should also help on Android and other new powerful mobile devices, but I haven't tested it on one yet. I really haven't used anything iPhone-specific which would intentionally break on other devices (I have tested the mobile version of the site on Firefox to validate this), but only testing will tell. Feedback is welcome.

I've also added a favourite stations list. The 'star' button to show the bookmark list is visible, but the editing functionality has not been published yet. Stay tuned for more!

O2 UK mobile users - your operator is breaking this site for you.

In a comment to a previous blog post on iPad/iPhone, Steve notified us that aprs.fi often does not work on the iPhone when used on the O2 UK 3G mobile carrier. It works fine on the same iPhone when he switches from 3G to a Wi-Fi connection.

Well, it turns out that O2 in the UK is running a transparent proxy server which compresses and modifies the web pages in many ways. Their intention is to make the pages smaller so that they would use less of their valuable radio bandwidth, but they ending up breaking the web experience really badly for their users. Here's what they do (information from Stuart Roebuck's blog and O2 user forums):

They re-compress images so that they look ugly on a device which has a bigger screen (such as the iPad, or a laptop connected to the iPhone).

Their proxy downloads CSS and JavaScript files and inlines them inside the HTML page before returning the HTML to the customer's phone. Normally the CSS and Javascript would be downloaded to the phone once when the first page from aprs.fi is downloaded, and after that they would be cached in the phone's memory so that they would not be downloaded again with the following pages. Now they're downloaded again and again with every page.

The CSS and JS code is actually much larger than most of the HTML pages downloaded from this site!

The inlining actually increases bandwidth usage (thus increasing your mobile data charges), slows down this web site, and often makes it unusable, because it breaks the HTML encoding and quoting rules for characters like < >. Steve's iPhone usually refuses to render the pages from aprs.fi due to this.

The inlining also removes comments, which might contain things like copyright clauses and software licenses. I suppose it's illegal to remove those.

For more information, please see Stuart's fine blog posts regarding the matter. I suppose the best options right now are (1) complaining to O2 about this, and (2) switching to another carrier, such as Three.

iPhone and iPod Touch fixes

Google has recently fixed a couple of bugs in the Google Maps API code, and both map controls and events have suddenly started working using the iPhone web browser. I've put them back in now, and the real-time APRS map is suddenly much more functional. Thanks for the little Christmas present, Google!

Look for me on HF digital modes during the Christmas holidays, I'm trying to be active from a few countryside locations.

iPhone & iPod Touch support greatly enhanced

I went ahead and bought an iPod Touch (Apple's opinion) for debugging my little aprs web project. The Touch is basically an iPhone (Apple propaganda) - without the phone and the camera. It's much cheaper, but it has the same operating system, web browser, and can run the same applications, so it's fine for the purpose. I got the new second generation 16GB model (with external volume controls, speaker, etc), around 300 EUR ($400 USD). It's very pretty, and the user interface is very cool indeed.

I did a little debugging yesterday evening and tonight, and fixed a few rough corners which broke things for iPhone users. The fixes should help other mobile browsers, too. All of the pages should now render properly on the iPhone & Touch. The real-time map now loads new items nicely, and handles panning of the map. The map controls (zoom, satellite/terrain/map buttons) do not work, but that's a bug in Google's code, and they know about it already.

The changes I did in the real-time map code had an interesting side effect which benefits all users. When you pan the map on a normal web browser, targets coming in the view load a bit quicker, and the overall experience is slightly smoother than before. What a nice surprise.

The bad news is that it seems quite hard to make the real-time map work on the S60 browser, at least on my E61i (the static map works fine, of course). It simply blows up, probably runs out of memory. Maybe it could work on Nokia's new Linux-based products. Too bad I don't have one to debug with.

I'll get back to this some another day. A lot of stuff needs to be done (a nicer front page with address search, etc).

Google Chrome supported

Google has just released Chrome, their new open source web browser. It seems to work just fine with aprs.fi, and it's blazingly fast too. Windows only, for now. They have a nice cartoon describing the internals of the browser. I'll add it to the list of supported browsers. Their EULA has some issues, though.

By the way, I'm shopping for an used iPhone or ipod touch. I need it for debugging and maintaining compatibility with aprs.fi. If you have one to sell or give away, let me know.

iPhone working (slightly)

iPhone support seems to be working slightly better now, but there are still some issues. They can be partially in Google's Maps API code, and partially in Apple's Safari code, and the fixes need to be done there.

There are bug reports in Google's bug tracker for the issues (I filed a couple, and there are a couple more submitted by others). I'm hoping that the good people at Google will fix them, or persuade Apple to fix their bugs.

• After panning the map, new points for the area are not correctly loaded, because the maps API doesn't give the correct corner coordinates for the currently visible area.
• You can't tap on an item, because click events do not fire on markers.
• You can't zoom or switch map type, since the standard Map controls (GSmallMapControl, GHierarchicalMapTypeControl) cannot be clicked on an iPhone.

Thanks go to Rasmus (a colleague at the $office) for borrowing his iPod Touch for a couple hours. If one of you happens to have a spare unit, you can find my address at qrz.com. :)

Update: I have obtained an iPod Touch for debugging, and enhanced iPhone support for APRS!