{"id":1639,"date":"2014-07-24T15:03:06","date_gmt":"2014-07-24T15:03:06","guid":{"rendered":"http:\/\/www.daveakerman.com\/?p=1639"},"modified":"2014-07-25T14:34:49","modified_gmt":"2014-07-25T14:34:49","slug":"pi-in-the-sky-telemetry-board-released","status":"publish","type":"post","link":"http:\/\/www.daveakerman.com\/?p=1639","title":{"rendered":"Pi In The Sky Telemetry Board Released"},"content":{"rendered":"

High Altitude Ballooning is an increasingly popular hobby (I nearly said that interest has been “ballooning”, but fortunately I stopped myself just in time …), bringing what is termed “near space” within the reach of pretty much anyone who is willing to put in the effort and spend a moderate amount of money.<\/p>\n

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Although it’s possible to successfully fly and retrieve a balloon with a simple GSM\/GPS tracker, the chances are that this will end in failure and tears. \u00a0GSM coverage in the UK is nowhere near 100% especially in rural areas which is where we want (and aim) the flights to land. \u00a0The next step up, in reliability and price, is a “Spot” tracker which works solely via satellites, but those don’t work\u00a0if they land upside down. \u00a0Also, neither of these solutions will tell you how high the flight got, or record any science data (e.g. temperature, pressure), or indeed tell you anything about the flight until they land. \u00a0If you’re lucky. \u00a0A lost flight is a sad thing indeed.<\/p>\n

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For some countries (e.g. USA, but not the UK), if you are a licensed amateur radio operator you can fly an APRS tracker, in which case the flight will be tracked for you via the ground-based APRS network run by other radio hams. \u00a0Sadly\u00a0UK laws prohibit radio hams transmitting from an airborne vehicle, so APRS is out for us.<\/p>\n

For these reasons, pretty much everyone involved in the hobby in the UK, and many other countries, uses radio trackers operating in an ISM (Industrial. Scientific and Medical) band where airborne usage is allowed. \u00a0These work throughout the flight,\u00a0transmitting GPS co-ordinates plus temperature and anything else that you can add a sensor for. \u00a0Many radio trackers can also send down live images, meaning that you can see what your flight is seeing without having to wait for it to land. \u00a0Here’s a diagram showing how telemetry from the flight ends up as a balloon icon on a Google map:<\/p>\n

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What’s not shown here is that, provided you tell them, the other balloonists will help track for you. \u00a0So not only will you be receiving telemetry and images directly via your own radio receiver, but others will do to. \u00a0All received data is collated on a server so if you do lose contact with the flight briefly then it doesn’t matter. \u00a0However, this\u00a0does not mean you can leave the tracking up to others!<\/span> \u00a0You’ll need to receive at the launch site (you have to make sure it’s working!) and also in the chase car once it lands. \u00a0The expense of doing this is small – a TV dongle for \u00a312 or so will do it, with a \u00a315 aerial and a laptop, ideally with a 3G dongle or tethered to a phone.<\/p>\n

Traditionally, balloonists build their own radio trackers, and for anyone with the skills or the time and ability to learn programming and some digital electronics, this is definitely the most rewarding route to take. \u00a0Imagine receiving pictures of the Earth from 30km up, using a piece of kit that you designed and built and programmed! \u00a0So if you are up to this challenge (and I suspect that most people reading are) then I recommend that you do just that. \u00a0It takes a while, but during the development you’ll have plenty of time to research other aspects of the hobby (how to predict the flight path, and obtain permission, and fill the balloon, etc.). \u00a0And when you’re done, you can hold in your hand something that is all your own work and has, to all intents and purposes, been to space.<\/p>\n

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For some though, it’s just not practical to develop a new tracker. \u00a0Or you might be a programming whizz, but not know which end of a soldering iron to pick up. \u00a0It was with these people in mind that we (myself and Anthony Stirk – another high altitude balloonist) developed our “Pi In The Sky” telemetry board. \u00a0Our principle aim is to enable schools to launch balloon flights with radio trackers, without having to develop the hardware and software first. \u00a0It is also our hope that older children and students will write their own software or at least modify the provided (open source) software, perhaps connecting and writing code for extra sensors (the board has an i2c connection for add-ons).<\/p>\n

The board and software are based on what I’ve been flying since my first “Pi In The Sky “flight over 2 years ago, so the technology has been very well proven (approximately 18 flights and no losses other than deliberate ones!). \u00a0So far the board itself has clocked up 5 successful flights, with the released open-source software on 3 of those. \u00a0Here’s the board mounted to a model B (though we very<\/strong>\u00a0strongly recommend use of a model A):<\/p>\n

\"pits<\/a>It comes in a kit complete with a GPS antenna, SMA pigtail (from which you can easily make your own radio aerial), stand-offs for a rigid mounting to the Pi board, and battery connectors. \u00a0Software is on https:\/\/github.com\/piinthesky, with installation instructions at http:\/\/www.pi-in-the-sky.com\/index.php?id=support, or there is a pre-built SD card image for the tragically lazy. \u00a0We do recommend manual installation as you’ll learn a lot.<\/p>\n

By now you’re probably itching to buy a board and go fly it next weekend. \u00a0Please don’t. \u00a0Well, buy the board by all means, but from the moment you decide that this is the project for you, you should task yourself with finding out all you can about how to make your flight a safe success. \u00a0For a start, this means learning about applying for flight permission (which, if you want to launch from your garden at the end of an airport runway, isn’t going to be given). \u00a0Permission is provided\u00a0together with\u00a0a NOTAM (NOtice To AirMen) which tells said pilots what\/where\/when your launch will be, so they can take a different path. \u00a0You also need to learn about predicting the flight path so that it lands well away from towns or cities or motorways or airports. \u00a0I hope I don’t\u00a0need to explain how important all of this is.<\/p>\n

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There’s lots more to learn about too, for example:<\/p>\n