Tracking the KJ7VBX-11 Pico-Balloon over Ireland & the UK - 8th May 2024

As we are now at the peak of the solar cycle, some radio amateurs are using WSPR on the 28 MHz band for their Pico-Balloons as they travel around the world.

Back in April of 2024, I had a post about reception of the KD9NGV pico-balloon as it made its way off the west coast of Ireland to the North Sea. See post HERE

I often see these pico-balloon on my receive list for 28 MHz WSPR but they're nearly all somewhere far away and the propagation mode is via the ionosphere. What I find interesting about the rare really close passes is that there is no propagation mode as such, the balloon is essentially line of sight to my location.

KJ7VBX-11... On the 8th of May 2024, I noticed that I was hearing the KJ7VBX-11 pico-balloon early in the morning just as it had woken up with the sun shining on it's solar panels. I was able to hear it pretty much all day from 07:40 UTC until 18:20 UTC.

During this time, it travelled from a spot off the west coast of Ireland, over the northern counties of Donegal, Derry and Antrim in Ireland, over the south-west of Scotland and then over Cumbria in England before falling silent for the night.

On the 9th of May, it woke up over the English Channel and then headed over the Netherlands.

The balloon is at an altitude of about 13,500 metres or 44,000 feet. The WSPR transmitter is supposed to be 20-milliwatts. As far as I know, it was launched on the 2nd of May 2024 but there seems to be very little information about it.

Format... Early on the morning of the 8th, I was the only person reporting it and it was the only signal I was hearing so I was able to do some tests without any confusion from other signals.

The WSPR transmitter on the balloon seems to have two formats. The first one is shown above. The transmitter turns on as a plain carrier for 30-seconds and then sends one WSPR transmission. I presume this carrier is to warm up the transmitter which is at or below 0 deg C and the 30 second carrier stops any drifting of the following WSPR signal.

The second format is shown below...

This time, there is a second WSPR transmission after the first one.

This is a sample of the decodes that I got in the space of about an hour...

0640    6  -1.6   28.126061   -2   KJ7VBX        IO33     13    361
0642    6  -1.6   28.126060    0   0O2MCY        GC73     53  13482
0650    7  -1.6   28.126060    0   KJ7VBX        IO33     13    361
0700    8  -1.7   28.126060    0   KJ7VBX        IO33     13    361
0702    8  -1.7   28.126061    0   0S2ZAQ        FR20     10   3937
0710    9  -1.6   28.126060    0   KJ7VBX        IO33     13    361
0712    8  -1.6   28.126061    0   0U2MNO        GJ72     10   6437
0720    9  -1.7   28.126060    0   KJ7VBX        IO33     13    361
0722    9  -1.7   28.126059    0   0X2LYI        II99     60   5842
0740    7  -0.3   28.126057    0   KJ7VBX        IO43     13    255
0750    9  -0.4   28.126057    0   KJ7VBX        IO44     13    343
0752    9  -0.4   28.126057    0   012OMZ        JP66     43   2019

The short format results in just a KJ7VBX decode.

The longer format results in an additional decode which are shown above in red.

At first sight, they look wrong. The callsign, locator and power levels seem to be nonsense. However note that the callsign field starts with a zero. This is a special data WSPR signal and contains the information about the location, altitude, temperature and battery voltage. It's just the WSJT-X receive software shows it in a format that doesn't seem to make any sense.

In conclusion... The balloon is currently heading over Europe so it's going to be line of sight to a lot of stations. Just listen on WSPR on 28 MHz and see if you can hear it.

Tracking a WSPR balloon on 28 MHz off the west coast of Ireland - Apr 2024

On the 28th of November 2023, Perri Moore KD9NGV launched a Pico-Balloon from Illinois in the United States with a solar powered payload that transmits a WSPR beacon on 28.1246 MHz.

Most of the Pico-Balloons launched from the USA tend to take a path closer to about 30 degrees north of the equator and cross areas like the north of Africa and south Asia. In contrast,  the KD9NGV balloon seems to have covered a much wider area and has been reported at more northerly latitudes as shown on the map above.

By the 16th of December 2023, it had gone around the world once! By the 19th of February, it had gone around the world three times. By mid April 2024, it has gone around the globe multiple times and the red dots on the map show where it was when I received some of the WSPR signals over the last few weeks.

What caught my interest was that back on the 7th of April 2024, the KD9NGV Pico-Balloon was off the west coast of Ireland. Most of the reception reports of the WSPR transmitter are via F2-layer propagation during the daytime. When it was off the west coast of Ireland, it was at about 40,000ft (12.2kms) altitude and line of sight to my location.

As can be seen from the map above and the reports below, my first reception report on the 7th of April was at 14:10 UTC when it was about 400kms to the west. A few others reported it via F2 layer propagation but I was the main one reporting it as it tracked its way up off the west coast of Ireland.

After 17:50 UTC, I lost it but it then came into the range of GM0HBF in the Western Isles of Scotland.

It then went silent as darkness fell. Once daylight broke again on the 8th of April, it was over the North Sea and GM4WJA started to report it.

At the time of the screen grab, LA3FY/2 in Norway was hearing it and it continued then over Scandinavia. It has since crossed over Russia and at the time of writing is up over the far north of Canada.

KD9NGV Payload... The actual payload pre-launch is shown below.

The 28 MHz WSPR signal is generated by a Si5351 clock generator and the power output is just 9 milliwatts... 0.009 watts!

The antenna is a vertical half-wave dipole made of #36 enamelled wire.  The top half is from the balloon to the U4B tracker (QRP Labs) and the lower half hangs below the tracker.  Three Powerfilm MPT 3.6-75  in a vertical triangle provide the power.  The complete payload weighs 12 grams.

The balloon is described as a "silver SAG Balloon with Helium.".

In conclusion... I have noticed these WSPR pico-balloons many times on the 28 MHz band before but they are nearly always flying over some exotic location. It was just unusual to have one pass so close and be line of sight.

Tracking the AF6IM Pico-Balloon on 28 MHz from the USA to China - Oct 2023

For the last 12-months or so, I have been being monitoring the WSPR beacon frequency of 28.1246 MHz nearly every day and uploading the reception reports to the WSPRNet site.

I noticed recently an unusual signal out in the Mid-Atlantic.. AF6IM. I thought at first it was a bogus WSPR report but then I noticed that I had heard the signal several times and it was moving!

After some checking, I discovered that the signal was actually from a Pico-Balloon with a 13-milliwatt WSPR transmitter underneath it. It was launched by Mark, AF6IM in California at the end of Sept 2023 and it has been slowly drifting eastwards since. At the time of writing on the 26th of October, it is over China.

The map above shows my reception reports of the 13mW beacon. It only operates for a few hours every day as it is solar powered and has no battery. That's why the signal is shown as small batches of signal locations in a row.

The pictured is further complicated by the fact that Mark actually had two 28 MHz Pico-Balloons in the air over the last few weeks.

The design of the WSPR transmitter is shown above and you can find more information about it HERE

The antenna for this 28-MHz transmitter is a very thin wire which is 2.54 metres long which is a quarter wave on 10m.

This photo by AF6IM shows the pico-balloon at launch. As the balloon gains altitude and the pressure reduces, the size of the balloon will get larger.

The solar cells are not shown.

Even though the original balloon looks very small, it's still able to keep a very small payload aloft at a high altitude. The chart above shows the launch of the balloon and floating along at an altitude of about 12,500m or 40,000ft. This is well into the Jet Stream and this is what is now carrying it  around the world.

The temperatures at this altitude are well below zero as can be seen in this image above. One obvious advantage in not carrying a battery other than additional weight is that there are no problems with a battery trying to survive at these low temperatures.

In conclusion... There have been plenty of other pico-balloons operating on lower frequencies in the past like on 14 MHz but I really don't have much interest in those bands. This is the first time I recall seeing one operating on 28 MHz.

What I find fascinating is that I have heard the little 13-milliwatt 28 MHz transmitter over 450 times over the last few weeks while it was hanging below a little balloon up in the Jet-Stream.

If you want to track it, you can follow it HERE

WSPR balloon on 20m over the Arctic - 10th June 2020

On the morning of the 10th of June, I left the radio monitoring the WSPR frequency on 20m to see if I would hear anything special. I noted two signals...

Australia... The first was the signal from VK3MO and VK3QN in Australia, always interesting because of the distance. I'm not 100% sure though if they were short path as shown on the map or long path. Might be something worth checking another time.

The one that really caught my eye was the VE3KCL callsign with the strange locator. I assumed at first a decoding error but no, it turns out to be a very small WSPR transmitter hung underneath a helium balloon over the Arctic Ocean!

As of the evening of the 10th of June, it was at an altitude of 10,000 metres, in constant sunlight, has a temperature of minus 6 deg C and is travelling at 18 knots.

It sends out a WSPR signals on 20m with a power output of 10 milliwatts. It was launched on the 16th of May 2020 and has is now starting its third circumnavigation of the planet.

More info here... http://qrp-labs.com/flights/u4b9.html

There are some of the WSPR decodes that I got which shows the locator square changing...

Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km az
 2020-06-10 20:58  VE3KCL  14.097177  -30  0 MR20 0.01 EI7GL IO51tu  4047 266 
 2020-06-10 20:38  VE3KCL  14.097178  -29  0 MR10 0.01 EI7GL IO51tu  4011 264 
 2020-06-10 19:48  VE3KCL  14.097178  -25  0 MR11 0.01 EI7GL IO51tu  4024 262 
 2020-06-10 18:38  VE3KCL  14.097184  -25  0 MR01 0.01 EI7GL IO51tu  3992 260

In addition to the QSPR signal, it is also sending out a QRSS signal in the form of a balloon!

The image I got a grab of isn't great but you can make out the circle in the waterfall.