I’m not sure how that might work but the balloon is tapping into what know as the LoRaWAN. This allows very limited amounts of data to be sent in each packet - just 51 bytes in Europe. But LoRa can be used for simplex radio communication between two stations. The power levels are very low but if each station had a yagi and line of sight of each other I think a reasonable range could be achieved.
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Indeed, there is a nice ham compliant solution for this: LightAPRS-W (+WSPR) tracker wspr and aprs… very small only 9g weight. Does 10mW on any HF frequency and 1w on vhf aprs… currently available… 
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Sadly that’s another mode we can’t us here because in the UK aprs can’t be used airborne. We share this rule with only two other countries, North Korea and Israel. 
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In case anyone in the UK was following the balloon this evening and noticed it was still transmitting after sunset (!) I seem to have discovered a sort of explanation.
The sheer number of gateways seeing the balloon caused a backlog somewhere with the result position reporting at the end of today was about two hours late. The balloon actually stopped transmitting a GPS fix at 17:18 UTC at which point it was a little south of Bournemouth over the English Channel.
I’m not sure if it was the TTN network being overloaded or the program I have running on a Raspberry Pi which interrogates the TTN servers and then uploads the position to the Habhub Tracker map. I’ve upgraded the Pi from an early model 3 to a Pi 4 which may help.
If the balloon survives tonight it should wake up over France where there are many fewer gateways so I don’t think we will see this overloading again.
Another school day! 
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I love your ISS model.
FYI I have some flexible wafers that are 2.3g for 1.1W rated
Can you explain more?
I used to fill balloons with H2 using caustic soda + aluminium. It must be the cheapest and easiest gas to produce. I would have thought two large plastic bottles would do (gas generator + scrubber)
Here we have ~10m band (0dBW,-10dBW)
There’s also 13.56MHz, (-10dBW)
and 6.78 (-20dBW)
No special conditions, so they do seem to be a free for all here.
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I was referring to bottled gas from a supplier. Here in the UK you can get a bottle of compressed hydrogen for about (from memory) £75 but you have to buy your own regulators which are around £150 and the bottle is only leased to you for £15 a month and you don’t get any refund for unused gas when you hand it back.
There have been a few trials with people making their own but getting it pure enough seems to be the challenge, specifically removing all the water vapour which gas produced by electrolysis contains. The need to remove any water vapour is because the balloon will experience very low temperatures, - 60C is possible and any water will turn to ice. There’s also the minor issue of safety producing hydrogen in volume at home.
However, a pico balloon (as they are called) like this one doesn’t need a lot of gas so it might be worth thinking about.
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It looks as if the balloon had an uneventful night and has woken up somewhere over the Mediterranean. The map below shows the location of the gateways which are picking up its signals, which started at 06:28 UTC. There is no GPS fix yet and I don’t expect that until later when the sun is high enough to generate enough power for the GPS chip to work properly.
Update: It has now given a location. This is much earlier than yesterday but that was over Scotland and down where it is now the sun will climb into the sky much faster. The GPS is still playing up with the altitude figure going frequently to zero but lat and long seem to be reliable. Ignore the other wavy purple line on the image below - this belongs to another balloon.
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Thanks for your currently updates!
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The balloon had a slow drift between Corsica and Sardinia today finally closing down as it approached the toe of Italy. The hysplit prediction suggests it might wake up tomorrow over Ukraine or Belarus, it seems to be following the green lines. Tomorrow might be the last day it will be visible before it leaves European airspace and dissappears for either a few weeks before emerging out of the Atlantic or just dissappears never to heard from again. I’m not taking bets on the most likely outcome but the little balloon is doing well so far.
The hysplit prediction, choose a colour but green seems likely if it stays at the current altitude.
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I hope the remains of what you have deposited into another country isn’t as damaging to wildlife and farm animals as the sky lanterns are John. I don’t expect there is any fire risk which the sky lanterns are also prone to causing. No problem if the balloon completely deteriorates on its way down to earth… I appreciate it must be very small as it’s amazingly lightweight!
73 Phil
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That is an aspect I’m conscious of, so I do a “rubbish offset” and collect many kilograms of cups, cans and bottles discarded in the road near my house over the year. I’m not trying to detract from the damage my balloon might cause, it really is something I have personally wrestled with. But how much plastic ends up in the sea from a typical microfibre fleece over its lifetime of washing? A few grams I suspect. Almost all of us are guilty of polluting and yes, if I didn’t launch a balloon it would be one less pollutant but one balloon a year (my current rate) is something I can live with - especially if a do another sweep of the lane outside tomorrow.
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I wouldn’t worry about your balloon at your rate of launch. If you look on this WEB site SQ6KXY Radiosonde Tracker Database? You will soon work out that there are loads of balloons launched by the Met Offices across the world and most are never recovered. I have recovered a few it’s good fun, like a free fox hunt.
73 de
Andrew G4VFL
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FB John and Andrew. Now I know what to look out for when walking.
73 Phil
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A quick update. The balloon is in Northern Greece and due to head north east then north. The hysplit prediction is itself split. Some paths take it east into Asia but other have it looping back into Europe. We shall see…
Where it is now:
And the hysplit predictions. Take your choice but the balance suggests east into Russia.
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An interesting experiment for sure.
John do you have a link to share on the hardware used. And any reason not to use APRS on ham bands ?
73 Joe
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Joe,
This is where I got the information for building the tracker:
The are several pages which are listed on the left.
Getting it to run was difficult because on the first attempt there was not enough memory left on the Arduino to run the code. With help from an expert I managed it using an older version of the Arduino IDE and a specific version of LMIC library. If you used the most up to date versions of everything it would not fit!
APRS is used for balloons, especially in the US but it is illegal to use it from a balloon in the UK so people originally, and still do to an extent, use RTTY but LoRa is now more widespread.
The first balloon tracker I built was this one:
https://www.daveakerman.com/?p=2101
You will find a lot of other balloon related stuff on Dave Akerman’s website.
I flew a Raspberry Pi Zero tracker to his design in 2020 under a latex balloon which reached over 30,000m. The tracker was successfully recovered afterwards and I was able to see all the photographs it had taken with the Raspberry Pi camera.
I made a poor video of the launch:
The main discussion forum for the type of balloon I am flying at the moment is here:
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Where does this come from? Is this something Ofcom impose in the conditions of getting a NoV to operate effectively \AM in the amateur bands?
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This page has a section on APRS. But I think the issue isn’t confined to APRS because there is a general rule which prevents ham radio use from a balloon or aircraft. This is why LoRa in certain ISM bands is used instead.
The page is a few years old and some of the links may not work.
https://ukhas.org.uk/general:aprs_legislation
I should add that I’m talking about the use in ham bands. The Ofcom document IR 2030 lists the licence exempt frequencies and I don’t think it stipulates specific modes. So you could use say WSPR or APRS on these if you met the frequency and power requirements - but no one will be listening. However, there are people about with RTTY receivers on ISM bands which are still used although 433/434MHz LoRa is the most widely used mode in the UK.
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Just hope it doesn’t float over the Deep South of the USA are some yahoo is likely to shoot it down.
Not a Ham, mind you, just a flat earther who things the aliens are coming to that his guns.
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Shame you aren’t here - my neighbour has a toyota mirai, with a 5kg hydrogen tank (and not much idea what to use it for)
I calculate that a 1m diameter sphere needs 450g of aluminium to fill it with H2 at STP. Not sure how much hydrogen you need.
You have to watch the temperature and reaction rate. (for high reaction rates, cooling is needed).
When I was a stripling, we used to fill the big balloons that were about 6" flat, perhaps 0.7m inflated with hydrogen. Tie a long oiled string to them with a paper bowtie at the top, so that they were just slightly bouyant. Then light the string and let them go. They would go off at about 30m up, in a nice zeppelin-esque fireball.
I used to make H2 in a glass bottle with Al+NaOH, and hold the balloon over the neck.
Well one day what I had was some anodised extrusion I cut up. It wasn’t reacting fast enough so I added some more, and then some more NaOH. Well you can probably see where this is going. When the NaOH finally ate through the anodising the reaction rate shot up, T rose, the reaction rate shot up more, and now hot caustic was foaming up into the balloon that was expanding furiously, while I held it to the bottle.
Leaving me to shut and avert my eyes, let the balloon go to do what balloons do, sprint to the garden hose, and hose the hot caustic off while stripping all my clothes off. (then clean dads car off. luckily a kak khaki morris marina, that frankly would’ve be improved by caustic damage)
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