Video: TinyGS, the Open Source Global Satellite Network with Jeffrey Roe EI7IRB

If you were to ask a member of the public about the subject of 'radio', they'll probably answer that it was some old technology that existed in the past and is now nearly dead. The reality is that it's hiding in plain sight. 

Think WiFi, Bluetooth, mobile phones, Satellite TV, Starlink, parking sensors, etc, we're surrounded by 'radio' technology. It's just that 'radio' has evolved and is increasingly in a digital format.

More and more devices now have microprocessors embedded and they are communicating with other devices using the concept of the 'internet of things'. One of the systems for doing this is LoRa (Long Range Low Power).

This concept has been developed so that radio signals from experimental satellites in low earth orbit can be received by hobbyists all around the world and then the data is fed back by the internet to the control station. One of the frequencies used for this is at 433 MHz in the radio amateur 70cms band.

TinyGS is one such network and is described as follows... "TinyGS is an open network of Ground Stations distributed around the world to receive and operate LoRa satellites, weather probes and other flying objects, using cheap and versatile modules."

Jeffrey, EI7IRB recently gave a presentation titled "TinyGS, the Open Source Global Satellite Network" to the Mid-Ulster Amateur Radio Club and they now have it up on their YouTube channel.

The video starts at about 7 mins, you can skip back to the start of you want to watch the introduction.

Tracking a high altitude balloon over Ireland on the 70cms band - 9th Jan 2024

 

Thanks to Robbie, EI2IP putting a post up on Facebook, I noticed that a high altitude balloon was crossing over Ireland due to the easterly winds over the country and it was transmitting on the 432-440 MHz 70cms band.

I remembered that I had managed to decode RTTY signals from a balloon over the UK a few years ago and I found it fascinating. It was always something on my 'to do list' to try again but I forgot all about it. When I checked today, that reception report was back in in July of 2018!

So there was no time like the present, I followed the links and started reading about it. 

Part 1 of 2... The high altitude with the amateur radio payload was named Flybag-2 and had been launched from Maastricht in the Netherlands. It was transmitting on two frequencies on the 70cms band with data on it's location, height and internal temperature.

The payload was transmitting using the Horus Binary (v1/v2) modulation format which is a digital signal that is way superior to the old RTTY mode.

I downloaded the software to decode the Horus Binary signals, starting to mess about with the various settings, tuned the radio to 437.600 MHz USB and listened....silence. 

The balloon had just cross over the east coast of Ireland and was heading west. I was using a homemade vertical colinear in the attic of my house which wasn't the best for listening for weak signals from a tiny transmitter 120kms away.

I also had the WSJT-X software running as well and I could make out weak traces in the waterfall. I tuned the radio down about 500 Hz to 437.5995 MHz. Eventually I could hear the signal weakly but still no decodes. Time to read the instructions.

The instructions said the audio level needed to be near -5dB. I had the volume well down and the software said it was 'good'? I tried turning the volume of the radio way up and success!

The stats show that I managed to get 20 decodes in total which is 20 more than I thought I'd get. The attic antenna is really blocked a lot in that direction so I was delighted to get anything.

Part 2 of 2... A few hours after Flybag-2, another balloon named Flybag-4FSK crossed to the south of Ireland. I had a lot more success with this one getting 71 decodes in total with my attic antenna.

The first decode was when the balloon was about 300kms away over the Bristol Channel and just below the horizon. My view to the east is pretty good and this resulted in a lot of decodes.

It was interesting to note that the signal was reasonably consistent up to about 00:24 UTC and then it dropped suddenly and the last decode was at 00:40.

This is the location of the balloon relative to my location. The balloon is slowly moving to the left (left).

This is the horizon from my location. The balloon from my point of view would have been moving slowly from roughly east to the south of me and then to the south west.

When the balloon was to the south-east, I was getting a lot of decodes as my horizon is close to 0-degrees in that direction. Once it got to 00:24 UTC, the local hill had an elevation of 1-degree. Beyond that, the signal dropped as the elevation of the hill got higher. 

After 00:40, the local hill had an elevation of about 3.5-degrees and it was now blocking the signal.

I knew my take-off in that direction was poor but it was interesting to see conformation of it.

High altitude balloon... There are generally two types of balloons. The one I heard back in 2018 was like a weather balloon, it went up to an altitude of about 20kms and then the balloon burst.

This time, the balloon reached a height of about 4kms where it levelled off. Unless the hydrogen/helium gas escapes or it hits rough weather, it should stay up for quite some time.

STEM... It also strikes me that this would make a great STEM project. Schools and colleges can't afford microsats but a low budget balloon could teach a lot about tracking, propagation, layers in the atmosphere, weather, etc. 

For more information, go to https://amateur.sondehub.org/

3000km plus contact made on 433 MHz from St.Helena to South Africa - 16th Oct 2020

On the 16th of October 2020, there was a remarkable 3000+ km contact made on the 70cms band between South Africa and St.Helena in the South Atlantic.

The contact at 433 MHz was made between Garry, ZD7GWM on St.Helena Island and Tom, ZS1TA in South Africa. The distance was approximately 3136 kms and what was even more amazing was that the contact was made on FM!

The power used for the contact was a modest 35 watts into a vertical antenna. This was a new distance record for a contact between South Africa and St.Helena on the 70cms band.

The mode of propagation was probably a marine duct as shown by this tropo forecast map from Pascal, F5LEN.

This 3000km+ tropo path between South Africa and St.Helena opens up on a reasonably regular basis. Back in November of 2018, there was an opening on 144 MHz as outlined in this previous post.

In June of 2020, the 2m path opened up again and the most recent opening on 2-metres was on the 23rd of September 2020 when ZD7GWM was worked by no fewer than five ZS stations... ZS1TA, ZS3CVB, ZS1CF, ZS3JPY and ZS1FC.

To put these remarkable contacts on 144 MHz and 433 MHz into context, the 3136 km distance is equivalent to the path across the North Atlantic between Newfoundland and Ireland.

Link...

1) Cape Town Amateur Radio Centre: ZS1TA & ZD7GWM Set New 70cm Distance Record - 16 Oct '20

Low Power Devices on 433 MHz

At the moment, I scan the 70cms band on a pretty regular basis and every so often, the radio will stop on  433.475 and 433.525 MHz. The signal sounds like a weak digital transmission and it's only there occasionally.

I thought perhaps it was due to an out of band signal and the receiver was being overloaded. Having said that, the Alinco 605E seems like a reasonable radio and the front end doesn't seem to be wide open like some of the handhelds.

After a bit of digging, I discovered that there is an allocation for low power device on the 70cms band. It's called LPD433... https://en.wikipedia.org/wiki/LPD433

This is the frequency chart which as you can see goes from 433 to 435 MHz.

I knew that some car key fobs and remote devices were using the band but I hadn't realised it was so extensive. Perhaps that is the reason behind the mystery signals?

What I didn't know was that in Europe, this allows licence free voice communications on 70cms.

"LPD hand-held radios are authorized for license-free voice communications use in most of Europe using analog frequency modulation (FM) as part of short range device regulations, with 25 kHz channel spacing, for a total of 69 channels."...from Wikipedia.

I noticed that Amazon are selling a dual 446 / 433 MHz radio as well...

Considering how easy it is to buy a radio, I wonder will there be more unlicenced operation on the 70cms band in future?