Presentation at Ham Radio 2013, Friedrichshafen

I've prepared a presentation for the Ham Radio 2013 event taking place this weekend in Friedrichshafen. The title of the presentation is "Providing authenticated amateur radio services on the Internet", and it'll be held at Conference Center East, room Paris, at 14:00. Same time and place as last year!

How can we provide Internet services restricted to amateur radio users with reasonable guarantee that non-hams do not gain access to the services, without an awful lot of manual work by the service provider and mailing license copies for every service? Current practices, alternatives, a proposal for better future implementation of distributed trust using X.509 certificates, and a demonstration of an implementation for a web service.

If you're an user of authenticated amateur radio web services such as the APRS-IS network, or Echolink, or Logbook of the World, this should be interesting. If you're developing a service like this, or would like to develop one, it should be especially interesting.

There's a catch, though. Due to a surprising event I won't be able to fly to Germany myself this weekend. Fortunately Erik Finskas, OH2LAK, has agreed to act as a proxy and present my material there! Not a bad deal, since he happens to be a seasoned professional in the right field, and has applied the presented technology both at work and in the linked UHF repeater network in Finland.

Join Amateur Radio on Stack Exchange

Stack Exchange is the latest internet gizmo at the crossroads of a forum, a wiki, a blog and a poll. The end result is a question and answer site which is much more qualitative and easier to search than any ordinary internet forum. Programmers and system managers may know it from the well-established Stack Overflow. In contrast, the amateur radio section is still at its infancy. It resides as a recreational topic in a staging area inauspiciously called “Area 51.”

Here is where things get serious and where your help is needed. Stack Exchange will not open a new Q&A site until they are absolutely sure that a critical mass of members will commit to actively participating. They are quite categorical about it and the vetting process is ruthless. “Area 51” is literally scattered with the mutilated remains of Q&A sites that were once to be. Yet, the amateur community at large cannot afford to miss out on this unique opportunity! This is why we need you to be part of the group of pioneers who started the Amateur Radio Stack Exchange site by following this link and commit!

Text by Serge Y. Stroobandt, ON4AA, CC BY 3.0

Updated statement on PRISM at aprs.fi

Last night's "statement" was generated using the PRISM involvement denial statement generator, and is not completely serious. Hopefully it'll serve as a little reminder of the privacy aspects of APRS. If you care about your privacy, you probably should not transmit your location to the public. With APRS, you have the privilege of switching your beacon on and off at any time, and it's sometimes a good idea to exercise that right. Some other tracking systems don't let you do that.

APRS data, like all other amateur radio communications, are public and unencrypted, and can be received, recorded and archived by anyone. With APRS, it's just easier to do so.

As for aprs.fi: there have been no requests from governments to aprs.fi at any point. They can just pull the data from the APRS-IS without asking if they happen to care, or use the aprs.fi web UI to look at whatever historic data there is – just like anyone else.

Statement on PRISM at aprs.fi

Dear aprs.fi users,

You may be aware of reports alleging that aprs.fi and several other APRS sites have joined a secret U.S. government program called PRISM to give the National Security Agency direct access to our servers. We would like to respond to the press reports, and give you the facts.

aprs.fi is not and has never been part of any program to give the US or any other government direct access to our servers. We have never received a blanket request or court order from any government agency asking for information or metadata in bulk, like the one Verizon reportedly received. We hadn't even heard of PRISM before yesterday.

When governments ask aprs.fi for data, we review each request carefully to make sure they always follow the correct processes and all applicable laws, and then only provide the information if is required by law. We will continue fighting aggressively to keep your information safe and secure. Any suggestion that aprs.fi is disclosing information about our users’ APRS activity on such a scale is completely false.

We strongly encourage all governments to be much more transparent about all programs aimed at keeping the public safe. It's the only way to protect everyone's civil liberties and create the safe and free society we all want over the long term. We here at aprs.fi understand that the U.S. and other governments need to take action to protect their citizens’ safety—including sometimes by using surveillance. But the level of secrecy around the current legal procedures undermines the freedoms we all cherish.

Embedded maps disabled temporarily

While investigating the problem with the Google Maps API I've disabled the embedded maps feature temporarily. Sorry for the trouble.

It now returns a blank page, so you'll see empty space where the map should be rendered. No errors should be shown to your web site visitors.

The map fails to load for some site visitors, giving an error about Google Maps API being disabled for the site. The error message does not seem accurate, since aprs.fi is nowhere near its usage limits, and an immediate reload of the page typically loads just fine. The error is sporadic, happens to some users all around the world, but not everyone (I haven't seen it), on all browsers (IE, Firefox, iPad, etc). The issue is being discussed on the aprs.fi discussion group.

Parser updates and new delayed packet filtering feature

I've updated the APRS device identification module Ham::APRS::DeviceID to include detections for new APRS devices (KissOZ, anyfrog, unknown mic-e, SARTrack, Altus Metrum, SM2APRS, aprsc, NW Digital Radio UDR56K). The new version, 1.06, has been published on CPAN for your open source pleasure, and installed on aprs.fi.

I also published version 1.19 of the Ham::APRS::FAP packet parser used by aprs.fi. It only includes a small fix to the binary value telemetry bit order in Base91 comment telemetry. But at least that keeps me in the regular 1 release per year schedule! Just in time!

The larger feature in the aprs.fi upgrade is that it now utilizes the sequence number present in Base91 comment telemetry for detecting delayed packets.

APRS packets notably lack any sort of sequence number that could be used to detect old duplicate packets arriving late, or to place them in the correct order. Newer Byonics trackers can transmit telemetry (battery voltage, temperature, etc) within position packets using the new Base91 comment telemetry format, which is quite tightly packed, and also includes a sequence number in a range of 0...8280. This makes it really easy to detect a packet having an older sequence number than the previously received packet. There are already a lot of those devices in use.

aprs.fi has now been updated to make use of the sequence number when available. It's more reliable and faster than the old methods of detecting too high speed or duplicate packet content. Due to the amount of broken igates and digipeaters delaying packets for minutes or tens of minutes (often due to a buggy Kantronics KPC3+ in KISS mode) it can make sense for a tracker to transmit the sequence number alone without any actual telemetry! Packets dropped due to this will be shown with this error message:

Delayed or out-of-order packet (sequence number)

In practice it will usually be shown together with the error message about dropped telemetry, since the telemetry content is also ignored due to the duplicate sequence number: 

2012-12-31 00:24:51 EET: N0CALL-9>SY0UWY,WIDE1-1,WIDE2*,qAR,N00CALL:
`pOnqgd>/'"KQ}MT-RTG|!D&='a|!w;a!|3
[Duplicate telemetry sequence, Delayed or out-of-order packet (sequence number)]

You can use the Decoded mode of the raw packets view to see sequence numbers and telemetry values decoded from each packet.

Time zone selection on aprs.fi

Most of yesterday I spent on implementing proper time zone selection on aprs.fi. You can now select whichever local time zone you wish using a (hopefully) user friendly map tool.

Click on Preferences (on the right side of the real-time map), select the Units and time tab, and click the Change button next to the currently selected time zone. That'll bring up the new time zone selection tool.

Point the mouse roughly at your location (the state or country which uses your preferred time zone), click, click Save to return to the main Preferences view, and click Save again.

You can also select either the time zone or country from the drop-down menus. Or, if browser geolocation works for you, click the I'm Feeling Lucky button. It's not very accurate (I'm being placed in Moscow for example), but it probably works for more than 90% of the population.

I didn't do all of this from scratch - I copy with pride. Thanks go to these two excellent open source projects: timezonepicker  and TimezoneJS.Date