The first time I heard about FANET was at a gathering of some paragliding friends last year. They mentioned that they can display each others position on their flight computers. While that sounds cool, I don’t often get to fly cross country any more. Thus this feature was not of particular interest to me. Then some months ago I read an article about the Skytraxx 3.0 in a paragliding magazine. It was mainly focused on the builtin database of aerial obstacles, namely dangerous cables. But it also mentioned that weather stations could broadcast wind information on FANET, which the flight computer would then display in real time. Now that was more interesting to me. The part I like the most about the FANET technology is that it is an open LoRa mesh network. I watched a video where the developer explained that it is even possible to transmit landing procedures based on wind direction to be displayed on the flight computer. Further pilots can send messages to each other, and change the mode from “flying” to “retrieve car” or “need a ride”. All of this together was too much to ignore.
While FANET was developed by Skytraxx, it is an open protocol, and other companies started including support for it in their devices. The Skytraxx devices that come with FANET, also include FLARM. FLARM started as collision avoidance system for sailplanes. But in the meantime, most light aircraft are equipped. Devices for paragliders only transmit to FLARM. They are unlikely to crash into one another due to the slow speed. But by transmitting their position, faster aircraft can be warned soon enough about their presence. Like FlightRadar for big airplanes there is GliderNet based on FLARM and SkyNet based on FANET. These sites are fed by ground stations that decode the signals broadcast by the aircraft. All you have to do in order to appear on these sites, is register with the Open Glider Network. If you register in addition with LiveTrack24 and link your OGN registration (the FLARM id), then your flights are automatically archived. What I like most about this, is that I can give the URL to my beloved ones. If I’m not home in time, they can check if I am still airborne, and where my last recorded position was. So in the improbable case of an accident, they could send search and rescue in the right direction.
Tag: GPS
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Flying AdHoc Network
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When a product is better than the description
When I was a kid I liked wrist watches from Casio. I had one with a calculator, one with an address database, one with an infrared remote control and one with an altimeter. But for the last 25 years I didn’t wear one. I don’t like to wrap anything around my wrist. And since I carry a phone, I have a way to find out what time it is.
When friends and neighbors started wearing fitness trackers, I thought I don’t need that. When I went running, I did it for my personal fitness, not to compare to somebody else. And I can care about my fitness without a device telling me to walk some more before going to bed. When my wive wanted to gift me a step counter for my birthday a couple of years ago, my response was: thanks, but no thanks. I have no use for a step counter.
Some times I brought my phone when I went running to record the GPS track just to try. Some co-workers upload all their activity to Strava, and claim “if it’s not on Strava, it didn’t happen”. Not so for me.
Since I started carrying my ultra light paraglider for run and fly, I took the phone with me more often. In the backpack it disturbs less than in the shirt. The main reason for carrying the phone was to be able to call for help in an emergency. And when I brought the phone with me anyway, I could just as well run the tracker app on it. But unfortunately it didn’t work very reliably. When the screen was off, it stopped tracking, and when the screen was on, it often registered fingers that weren’t there. So it happened often that it stopped tracking after a while, or deleted the track entirely. Sometimes I had a ton of apps open after running and I didn’t know what else happened to my phone. But still, with the few tracks that recorded at least the uphill running part, I could see my progress on that segment. That turned out to be more interesting than I anticipated.
So when my wife recently wanted ideas for my birthday, I told her “a cheap wristwatch with GPS tracker, that works without a crappy lock-in smartphone app”. My absolute nightmare is to have a closed source device that tracks my every move, where I have no control over the data it collects. Worst of all, it would become useless when the manufacturer decided to stop maintaining the app. I don’t want devices with planned obsolescence. Of course I had to do the research myself. On the product page they only mentioned their iOS and Android apps, which are of no use to me. I noticed a while ago, that there are some packages in the debian repo for Garmin Forerunner devices. Further research brought me to quite complicated methods to get the data from these watches. But then I found a page that stated that when you plug in the watch with its USB cable to a computer, it mounts a filesystem and you can just copy the activity files. If it is really that easy, then I really don’t understand all the fuss. Everything seemed to indicate that all Forerunner watches come with a USB cable for charging the device that also acts as a data cable. It is beyond me why they don’t mention that explicitly on the product page. So, for my purposes a relatively cheap Forerunner 30 or 35 should be just fine.
And so I got one for my birthday from my wive. It even has a heart rate sensor that I wouldn’t need. And indeed, just plugging it in with the USB cable, I can grab the fit files and either upload it directly to Strava, or convert it to a more common format using gpsbabel. -
an exact clock for a vintage car
Since I drive my vintage XJS not too often, I disconnect the battery. This is to prevent if from going flat before I want to use it the next time. Of course it would be better to install a special charger for classic cars. But there is no outlet in the underground car park. The car starts when I want to use it, so one could say: mission accomplished. If only there was no clock in the dashboard. It doesn’t run when the battery is disconnected. Having to adjust the clock every time is not the solution I was looking for.
My first idea was to get a DFC77 radio clock with hands, and put it inside the case of the original dash clock. All the clocks that had hands were too big to fit into the case. So I ordered a small module with an LCD. The problem was that it had good reception at home, but not inside the car. The long waves seem to have a hard time penetrating the Faraday cage of the car body.
The next option that delivers exact time over the air is GPS. So I ordered a cheap GPS receiver from China, and built a prototype with an AtMega microcontroller and a small OLED. The prototype kind of worked, but after the first drive, the GPS module failed completely. So I ordered a better one from an AdaFruit reseller in Switzerland. This module still works very well, but I found out the hard way that it needs a very clean power source. The next problem were random failures and reboots of the micro controller. This turned out to be caused by memory overruns. They are harder to detect on a micro controller than on a regular computer. The display needs a framebuffer in RAM, and for the GPS I need enough space to store and parse the full NMEA sentences. I tried to reuse and re-initialize the same memory for every reading, but that didn’t work out. Neither didn’t I find a similar controller with more RAM. If I was going to produce a number of devices I would for sure use a better controller, but as it is a one off prototype, I just used two AtMegas. One for the display, and one for the GPS.
GPS has no reception in tunnels and underground parking garages. So I planned to implement a simple counter that just increases the time when GPS reception was lost. But then I decided it was not important enough. Instead I wanted to proceed, and have the device ready in the car. But I couldn’t resist to display a leaper for when there is not reception.
In a classic car, everything should be in original condition, so I didn’t want to destroy the original clock. Instead I was looking to buy a used clock that didn’t have to be in working condition. The ones I found in Switzerland were too pricey for only the case. So I found one on ebay for £22 that was shipped from the UK.
The problem that remains is that the OLED sometimes initializes with a random dot pattern and stays that way until the next power cycle. It happened more when I had it connected directly to the main battery. But since I connected it the the dash back light, it never happened again. So maybe it is important how fast the voltage increases when power is switched on.
As usual, the code is on github.
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VW Bus Treffen Schwarzsee
Last saturday we went to the vw bus gathering at the Schwarzsee. There were more than 460 VW Busses present from all different types. I had the impression, to see less vehicles than last time, but comparing the pictures from 2009, I’m not so sure anymore. It’s amazing in how good a shape some of the vintage hippie mobiles still are.
By accident we discovered a DVD of “The Bus” movie on the bugbus booth. It was apparently crowd-funded by a kickstarter campain.
Of course I went for a short flight, to see the event from the top, while Mirella and the kids listened to a “Guggämusig”.
The drive there was a good opportunity to test the SPOT Connect that I got for my birthday. [map link] Contrary to my previous understanding, It doesn’t provide internet connectivity, but allows to send custom messages to pre-defined phone numbers and eMail addresses. As the simpler SPOT devices, it contains a transmit only unit for the GlobalStar satellite network. The very bad thing about it, is that it was hard to perform the required firmware upgrade. They provide the upgrade program only for Windows and Mac. But communication afterwards seems to be better, as lined out by this blog post.
Enough blabbing, pictures tell more than words:
