LoRa LoRa Laughs!

Due to the restrictions on airborne amateur radio operation in the UK High Altitude Balloon (HAB) enthusiasts have been forced to utilise licence exempt low power devices in novel ways to make radio trackers for their payloads. I have written plenty on this blog about my HAB tracking, the UKHAS distributed listener network and my own flights.

Until recently the preferred method was to use RTTY transmissions, however the advent of the IoT (Internet Of Things) has seen manufacturers of radio modules develop devices to increase both the range and reliability of communication between ‘connected’ embedded devices.

One such development are LoRa devices, primarily for devices to connect to a global wide-area network LoRaWAN, more information can be found at the LoRa Alliance in addition there are some open hobbyist networks such as The Things Network using these devices.

Using chirp spread-spectrum modulation these LoRa devices are marketed as being capable of robust, interference and fade resistant communication over longer distances and higher data rates.

The UK HAB community has begun experimenting with these devices and one of their keen proponents is Dave Akerman (M0RPI). Dave has developed both payload software for the “Pi In The Sky” PITS tracker along with Anthony Stirk (M0UPU) and gateway software in collaboration with Robert Harrison M0RJX. The ‘gateway’ is the necessary receiver element to upload the data to the tracking system. (all software is on the PITS Github page)

Dave gave an informative presentation on LoRa at the UKHAS 2016 Conference which is now available online (starts around 3 minutes in)


I had intended to fly a LoRa transmitter on my 2015 Hamfest balloon but it stopped working at the eleventh hour and hadn’t done anything else with LoRa till recently.

Spurred on by the conference presentation and the fact more and more flights are carrying LoRa I invested in one of the Raspberry Pi expansion boards sold by Uputronics and built up another prototype tracker with a working LoRa module.

I have done talks at various radio clubs and societies and demonstrated it working but hadn’t actually received a ‘real flight’ as opportunities have been scarce due to the weather. However in the few weeks I have tracked a couple of flights receiving both telemetry and image data, getting a couple of complete images from the imaginatively named ‘SPACE’ flight.

Dave Akerman also flew a flight experimenting with multiple payloads using Time-division multiplexing (TDM). It had 10 small of “AVRLoRaNut” trackers (of Anthony M0UPU’s design) all set to the same frequency (434.450MHz) and same transmission mode. The trackers took turns to transmit, with each one allocated a particular transmission slot in a 20-second cycle. The cycle was GPS-timed but, if any tracker lost GPS lock then it derived timing from the transmissions from the other trackers (the LoRa devices are also receivers) All 10 trackers were suspended from the same balloon. This was in preparation for the ‘Operation Outward‘ re-enactment next year (Steve Randall gave a presentation on it in the above conference video starts 1 hour 16 mins in)

I successfully received telemetry despite the flight not being local and constantly heading away from me as can be seen in the screen shots.

Always a busy man Dave also flew a flight with an experimental camera setup. The SSDV images this time came from a Nikon compact camera, connected to the Raspberry Pi via USB, and using gphoto2 software to take and transfer images to the Pi where they were stored, resized and converted to SSDV format for transmission. These were large images with a high quality SSDV setting so lots of packets per image, approx 1400 per image in testing. 

This flight was using a 868MHz LoRa device, rather than the usual 434MHz due to the IR2030 restriction on bandwidth and duty cycle. Dave was using his Turbo-X or Mode 4 setting which is as fast as LoRa will go within IR2030 bandwidth restrictions (approx 8 packets / 2k bytes per second)

I hastily ordered a 868MHz device and soldered it in the spare slot on my gateway and built a collinear for 868MHz similar to the one I built for ADB-S reception (see video here).

You can see it lashed up just below the dual-band collinear – not ideal mounting and it wasn’t tested in anyway, built blind!  The less than optimal setup at UHF, the insane data rate and the distance (>100miles) were going to make reception difficult, so I was pleased I did manage to receive telemetry and image packets.

 
Most of the current LoRa development in the HAB community has tended to be on the Raspberry Pi due to the use with SSDV and the easy availability of cameras and ready built kit. LoRa is of course available on the Arduino platform and I had purchased a couple of ‘Dragino’ shields (pictured below) with a LoRa device on.

Dave has done some work on a AVR tracker software and a simple Arduino ‘Serial’ LoRa receiver. The receiver connects to a host PC appearing as a serial port and by running some gateway software the receiver can be configured via the serial link and received data is sent back to the gateway to be uploaded to the Habitat tracking system and SSDV system – the software can be seen here during the ‘Operation Outward’ test flight.

This gateway software is written in Pascal using Delphi and is not as functional as the Raspberry Pi Gateway software. Dave has made the source code available but I am not au fait at all with Delphi however I installed the free development IDE and intended to get in and make modifications but it seems to require a non-free(?) library for the serial comms so ditched the idea.

Instead I have spent the last few days developing a C# .NET version using Microsoft Visual Studio (the community version is free) and also have been modifying the Arduino code in the receiver to add functionality, such as storing the SSDV images locally.

It is still a work in progress but I have made a video showing the current state


Anyway as Cilla Black would say it’s been a Lorra Lorra Laughs!

Hamfest Balloon – Some analysis

It has been five days since PINKY and PIGLET had their successful flight into the stratosphere. I have been studying the telemetry data and the photographs. I am really pleased with them but it makes the failure of previous Eggsplorer-1 mission to get any wow images more painful.

I contacted some local and national newspapers about the flight but with little response. The Register IT news website did put an article on http://www.theregister.co.uk/2015/09/28/pigs_in_spaaaace

I checked out the telemetry statistics on http://habitat.habhub.org/stats/ and was impressed with the number of people who tracked (as can be seen in the pie chart below) I know that several interested parties have since visited the UKHAS wiki and have been asking questions on the IRC channel on how to do a flight and/or develop their own trackers. Naturally I have also been thinking about some possible future flights.

While the novelty of flying something into space, be it a toy pig or an egg is satisfying I would like to make any future flight serve some purpose, whether collecting more data or ideally doing some experiment with radio even if it within the constraints of the UK draconian regulations when operating in the air!

One set of data I did extract was the temperature profile during the flight. PINKY had two sensors, one internal to the Styrofoam box, the other external. PIGLET also had a temperature/pressure sensor but it was giving odd readings during the flight so have ignored that.

The graph shows internal/external temperature recorded by PINKY against altitude, there are two plots for each showing the ascent profile and the decent. The lowest temperature recorded by the external temperature was -49.5°C   (-57.1°F) and the foam did a good job of insulating the internal electronics, though it drop below 0°C during the decent.

One thing I will do on the next flight (if it happens) is take a lot more photographs, using a 32GB memory card I could have held a lot more images. Also I will look at embedding the GPS coordinates (geotagging) into the image files.

I will also put on board a video camera, I did purchase a cheap dash cam type for £20 one off eBay for the Eggsplorer-1 but didn’t use it because of sea-landing, I need to sort out powering it as the internal battery wouldn’t last for the duration of the flight.

I have still to investigate the issues with the LoRa as to why it failed. This weekend Dave Akerman is flying three balloons in succession with LoRa tracker modules. They will be set up to work in a mesh, receiving and repeat each others telemetry. Sounds an interesting experiment, I will have to set my LoRa gateway back up and attempt to receive them.

First HAB flights were a success

Two years after discovering the hobby of High Altitude Ballooning I have migrated from being just a passive tracker and finally completed my first flights assisted by other members of the South Kesteven ARS.

Ready to launch

Back in March I posted about the opportunity I had to make a launch at this years Swaton Vintage Day and the 10th World Egg Throwing Championship

South Kesteven ARS were going to hold a special event station with the call sign GB2EGG. During the planning stage I jokingly suggested throwing an egg in to space on board a balloon, I shouldn’t have yoked…

The whole venture captured everyone’s imagination, sadly putting the special event station in the shade but we certainly got a lot of publicity for the club and amateur radio in general.

Featured on front page of local paper

There was certainly a lot to learn and get organised, not only did I have to design and build the flight computer which was the easy part but I had to build the payload containers get the balloon, parachute, cord the lifting gas (Helium) and build a filler assembly as well as getting official permission from the CAA for the launch.

The information on the UKHAS wiki as well as Dave Akerman’s High Altitude Ballooning, From The Ground Up (and back again) were invaluable.

The cost of this venture was not insubstantial and thankfully MADHEN – The Ultimate Party Band agreed to sponsor the flight which helped greatly and I received a nice donation from fellow club member Mark Orbell (M0OBL)

Months of work and lots of last minute hitches but I was ready.

Two flights were planned an altitude ‘burst’ flight with a raw egg payload with a parachute decent. The main tracker MADHEN would broadcast SSDV images and telemetry with a telemetry backup tracker EGG1 suspended below it.  The second flight was a foil party balloon ‘floater’ with a tracker kindly donated by Steve Smith G0TDJ of ProjectAVR

Both flights flew and were a great success, unfortunately the SSDV tracker failed early in the flight so no in flight images were received.

The main payload is pictured below before the flight resting on its side. The Styrofoam box contained the flight computer and radio transmitter with a camera attached to the Raspberry Pi and the “flying saucer” model which contained the egg was positioned to be visible.
 

As this test image shows the ‘egg saucer’ should have had the earth below it.

However the arduino based backup tracker which was suspended below it worked perfectly.

There were some issues with getting CAA approval because the sky was very busy on the day including the last remaining Vulcan Bomber VH-558 making its farewell flight in the area, cue jokes about the Vulcan getting scrambled… but approval was given for a morning flight, not ideal for the organisers but we were still a spectacle for the handful who were there early.

Starting the fill

Checking the neck lift, made difficult by the wind

Stewart (M0SDM) helping me tie off the balloon and payload cord
The strong gusty wind made launch difficult
Me and Stewart making a dash to assist the launch
Someone was on hand to capture it on video for The World Egg Throwing Federation

It started so well,  I was receiving telemetry and image packets and then transmission stopped

However as I said the other tracker worked brilliantly and this was the final flight path as visualised in Google Earth. The ascent and decent rate and the burst altitude were exactly as planned and predicted, so I know I got the neck lift measurement right even with the high wind on the day.

Path of MADHEN/EGG1

A splashdown at sea was inevitable due to the wind conditions, hopefully it it survived the landing it may wash up on a beach somewhere and we can retrieve the images.

With what little Helium remained I was able to lightly fill and launch a foil party balloon carrying a blown egg shell as a ‘floater’ which made a valiant attempt to reach the continent at 6-7km high travelling at 120+km/hr where it reportably hit bad weather and was downed.

Path of EGGDX in comparison to MADHEN/EGG1

 All in all an eggscellent day!

Eggciting HAB projects

I have a new high altitude balloon project, this one is very Eggciting.

In June my club South Kesteven Amateur Radio Society (SKARS) will be operating a special event station at the Swaton Vintage Day held at Thorpe Latimer in Lincolnshire. 

The 2015 Swaton Vintage Day will also host the 10th World Egg Throwing Championship  and in recognition the special event station will have the call sign GB2EGG. This popular annual show raises money for local, national and international good causes.

Egg Throwing is recognised by the English Sports Council and the sport is taken very seriously by some competitors. Hundreds of competitors from Europe and around the world are expected to compete this year. Last year’s event attracted teams from Germany, Slovenia, Hong Kong and Brazil.

While planning the special event station I jokingly suggested throwing an egg in to space on board a balloon, I shouldn’t have yoked as it is now a serious project. The idea coming from Dave Akerman’s Spudnik flight for Heston Blumenthal’s Channel4 television program.

Image with the permission of Dave Akerman

Subject to Civil Aviation Authority clearance and weather conditions I will hopefully launch a high altitude balloon carrying one lucky egg into the edge of space and then dropping it back to earth under a parachute. In addition to the plucky Eggstronaut the balloon I have called Eggsplorer-1 will carry a radio transmitter to broadcast its position, altitude and live images of the journey back to earth.

On board cameras will record the journey to be recovered on a successful return to Earth. Radio enthusiasts all around the country will be able to assist receiving the data and pictures and track the progress of the flight via the UK High Altitude Society tracking website.

More details and progress will be posted on here and on the Eggsplorer-1 website  and you can follow developments on twitter @eggsplorer1South Kesteven ARS welcomes anybody with an interest in radio communications, so if want to be involved in this and other events like this please visit us at the show or visit the South Kestevan ARS website and on twitter @M0SKR

I have already begun development of the payload, unlike the moth-balled NERD-1 payload this one will use one of the Raspberry Pi boards since I want to transmit SSDV images live and it supports its own specially designed camera modules. NERD-1 will still fly as a backup tracker.

Dave Akerman (M0RPI) and Anthony Stirk (M0UPU) have developed the Pi-In-The-Sky ready made boards and the design and software are open-sourced, using this as a starting point together with Phil Heron’s (MI0VIM) SSDV software I quickly had a prototype dubbed NERDPI running.

I did have an issue since the GPS module I currently have only outputs serial data so had to use one of those small TTL USB-Serial adapters and spun some of my own code to get the data out and was soon successfully decoding my own transmissions from the shack and uploading them to the Habhub system.

Today has seen the spectacular partial solar eclipse here in the UK, during the eclipse several HAB flights were launched to try to capture images above any cloud cover (details here)  Fellow SKARS members and members from the Grantham ARC were keen to decode the SSDV images themselves as the BBC Stargazing Live balloons were flying from nearby Leicester.

So on Wednesday I did a talk and demonstration to show how to track and decode the images, it was well received and I uploaded pictures of the audience to the system.

Unfortunately technical issues prevented live images from the Stargazing HABs being transmitted but I was able to decode some images from the University of Southampton OLAF payload They were only lo-res but still pleased to get decodes here it was a good distance from me.

Here in Newark the sky was beautifully clear so the eclipse was visible and spectacular, where OLAF was flying was covered in cloud, so the mission was a success.

   

434MHz Balloon flights this weekend

Quite a few HAB flights this weekend, details here

http://www.southgatearc.org/news/august2013/434_mhz_balloons_launch_this_weekend.htm

Hopefully Dave Akerman will be able to complete the Babbage Flight, more details on his website
http://www.daveakerman.com/?p=1355

This wonderful concept of this is to take a Raspberry PI Mascot Teddy Bear into the stratosphere and then launch it Felix Baumgartner style back to earth. Details of the payload here http://www.daveakerman.com/?p=1321  

We wish Babbage well on his travels, won’t be able to monitor it myself as have other committments.