OH3VHH is the call sign for an amateur radio high-altitude balloon flight organized by Hämeenlinnan Radioamatöörit amateur radio club, call sign OH3AA, in Finland. The primary purpose of the flight is to be a scientific experiment: to test a variety of radio transmitters for tracking the balloon and to record video and photos during the flight.
See the main page for OH3VHH flight for detailed information about the flight hardware and instructions on how to receive the radio transmissions emitted by the payload.
Latest update: July 16th 2021
Follow the YouTube live stream from launch site!
I’ve been planning to do a new high-altitude balloon flight for a long time — after the first flight in August 2017 partially failed. While we got some really awesome looking still photos, we were not able to capture any video because the GoPro 5 Session camera was overheating and shut down early. Additionally, we failed to track the balloon using my custom LoRa tracker, because of a simple mistake of using the wrong antenna port in our receiver :). Luckily, the 2m Trackuino APRS tracker was working reliably throughout the flight!
For the upcoming OH3VHH-1 flight, we’ve chosen to use two Lightdow full HD video cameras that were also used successfully on some Overlook Horizons HAB flights. Based on my battery run-time tests, they seem to reliably record video until the SD card is full and they do not produce excessive amounts of heat.
We were also able to acquire a large cylinder of hydrogen gas for filling up the balloon. The cost of helium is currently significantly higher, and it seems to be difficult to buy helium in large quantities at all right now.
Planned launch time is on Saturday, July 17th between 7:00-8:00 UTC. We will begin flight preparations already at 6:00 UTC. In case we need to cancel the flight because of bad weather, we will attempt to launch the balloon again either on Sunday, July 18th or on Saturday, July 31st.
Planned launch location: near Hämeenlinna, Finland
Planned flight time: 90 minutes
Estimated ascent rate: 5 m/s
Maximum estimated altitude: 27-30 kilometers
Based on the current predictions (on July 16th), the balloon will float towards east and would land somewhere near the city of Lahti.
Tracking and following the flight
It is possible to track the balloon even without any radio equipment: the 2m APRS tracker transmissions should get automatically picked up by local APRS repeaters and IGate devices, so it should be possible to follow the balloon location in aprs.fi using call sign OH3VHH-11:
Additionally, we will attempt to provide a YouTube live video stream from the launch site on the Finnish Amateur Radio League YouTube channel. The video stream will include the DVB-S1 video transmission from the balloon.
Follow the YouTube live stream from launch site!
In case you’re located in Finland and you wish to set up your own radio equipment, see the main page for OH3VHH flight for detailed information about the flight hardware and instructions on how to receive the radio transmissions emitted by the payload.
Radiosondes and DVB-S video
We also wanted to do some experiments on new radio hardware on the OH3VHH-1 flight, so we ended up adding two transmitters to the payload: a reprogrammed Vaisala RS41 radiosonde as a 70cm band APRS tracker and a DVB-S1 live video transmitter that follows the hardware setup Australian Amateur Radio Experimenters Group (AREG) has used in March 2021 on their Project Horus 55 flight.
A radiosonde works well as an APRS tracker because they’re free to collect, and they’re very lightweight devices, specifically built for high-altitude balloon tracking. The Vaisala RS41 radiosondes are used extensively for atmospheric sounding by the Finnish Meteorological institute, so they’re easily available in Southern Finland to be collected once they land, an activity called radiosonde hunting (YouTube presentation). We’ve been tracking nearby radiosondes since fall 2019 at the OH3AA club using the excellent radiosonde_auto_rx software, as there is an automated radiosonde launch site about 50 km away from the club location launching 4 sondes every day, so plenty of radiosondes will land nearby with suitable winds. It’s also possible for anyone to track radiosondes in SondeHub that combines data from a global network of receivers connected to it.
I got the idea to add a live video transmitter to the balloon payload when I followed the preparations for the Project Horus 55 flight, which used a combination of a Raspberry Pi Zero, a LimeSDR Mini and a small 70cm band PA board by G4BAO as a DVB-S1 video transmitter. The small size and wide availability of all of these components made it easy for us to build a similar transmitter. In fact, I already had a LimeSDR Mini and a Raspberry Pi Zero with a camera around, so I could start testing the setup early. I also wish to thank Mark VK5QI (Project Horus / AREG) for answering all of our questions regarding their DVB-S transmitter setup, especially the idea they had that using a quadrifilar helical antenna with the transmitter would likely result in significantly less signal fading. Anyway, our hope is to have a couple of stations attempting to receive the live DVB-S video stream during the flight.
See the main page for OH3VHH flight for more details about the DVB-S transmitter and instructions on how to receive the radio transmissions emitted by the payload.