Tagged: high altitude balloon

Project Horus 55: Live Video from a High Altitude Balloon

Project Horus 55 was a project that involved creating a high altitude balloon with payload that could broadcast live video down to ground station observers, as well as creating the ground station receive hardware. On March 7th 2021 the balloon was launched and ground station observers successfully received the live video.

The transmission hardware onboard the balloon was a Raspberry Pi Zero which captured and compressed the video, and a LimeSDR Mini which broadcast a DVB-S signal at 445 MHz. Power amplification was provided by an 800mW LDMOS amplifier. On the ground station side, RTL-SDRs were used as the receiving hardware and SDRAngel as the software. Although high gain auto tracking Yagi's were used by the main ground station team, it's interesting to note that the balloon chase team were also able to receive the video with a simple vechicle mounted turnstile.

In the video below Mark VK5QI who was one of the people behind the project discusses the setup before the launch.

Live Amateur TV from 100,000 feet!

The video below shows the launch and some of the live video received.

Testing VOR Navigation in the Stratosphere with an SDRplay RSP1 and High Altitude Balloon

Over on the SDRplay blog Jon has posted about the STRATONAV experiment which makes use of the SDRplay RSP1 software defined radio. The STRATONAV experiment uses high altitude balloons to carry the RSP1 as well and a commercial portable receiver. The two receivers were configured to receive aircraft VOR navigation signals in order to test the effectiveness of VOR when used at extreme altitudes of up to 28 km. The VOR navigational data was then compared against GPS tracks, resulting in a measure of how well VOR worked at those altitudes. 

VOR (aka VHF Omnidirectional Range) is a navigational beacon that is transmitted between 108 MHz and 117.95 MHz from a site usually at an airport. In the past we have posted about VOR a few times as it can also be decoded with an RTL-SDR, or used for passive doppler aircraft radar. 

The results showed that VOR navigation does indeed continue to function at extreme altitudes, proving that it can be used as a back up navigation system for stratospheric platforms. They also note that VOR navigation could also be used as a primary navigation system on smaller stratospheric platforms due to its low cost and low complexity to implement.

The full academic paper is available on sciencedirect, or for free via Sci-Hub.

SDRplay RSP1 (seen bottom right behind the metal mount) Flying on a High Altitude Balloon

Tracking Multiple Amateur Radio APRS Balloons with RTL-SDRs

Last month Jeff Deaton from "Edge of Space Sciences" (EOSS) presented a talk called "SDR Multi Balloon Tracking", where he discusses how EOSS are using RTL-SDR receivers to track their APRS high altitude balloons. EOSS is a Denver, Colorado based non-profit organization that promotes science and education by exploring frontiers in amateur radio and high altitude balloons. The talk overview reads:

Review of the software defined APRS system being used to track multiple balloon flights at EOSS. Overview of primary features like the graphical user interface and landing predictions as well as a discussion of the open source software used to power the system like GnuRadio, Dire Wolf, and Aprsc.

It appears that they've created some interesting software that they run on small portable computers that they take in chase vehicles. The software uses an RTL-SDR to receive the APRS signal from the high altitude balloons that they've launched, allowing them to track and predict the flight path, and ultimately recover the balloons and attached cameras.

Creating a High Altitude Balloon Telemetry System with Raspberry Pi, RPiTX and RTL-SDR

The 2M TX Filter by ZR6AIC
The 2M TX Filter by ZR6AIC

Over on his blog ZR6AIC explains how he's created a full HAB (high altitude balloon) telemetry transmit and receive system using RPiTX and an RTL-SDR dongle running on a Raspberry Pi 3.

RPiTX is software that enables the Raspberry Pi to transmit any modulated signal over a wide range of frequencies using just a single GPIO pin. However, the transmission contains multiple harmonics and thus requires sufficient filtering in order to transmit legally within the 2M ham band. To solve this ZR6AIC uses a 2M Raspberry Pi Hat kit which he designed and created that contains two low pass filters as well at the option for an additional power amplifier.

The rest of ZR5AIC's post explains how his HAB telemetry system combines the Raspberry Pi 3, RPiTX 2M Hat, RTL-SDR, a GPS unit, battery, temperature sensor and optional camera into a full HAB transmitting system. He also explains the software and terminal commands that he uses which allows him to transmit via RPiTX a CW beacon and GPS and temperature sensor APRS telemetry data with the Direwolf software. Full instructions on setting up the alsa-loopback audio routing is also provided.

Launching the High Altitude Balloon.
Launching the High Altitude Balloon.

Creating a FSK SSDV data system for High Altitude Balloons

David and Mark are building a 115 kbit/s FSK SSDV (slow scan digital video) data system for high altitude balloons. In their system, on the balloon transmit side they use a Raspberry Pi, Raspberry Pi camera and a RFM22B wireless transceiver modulator board to transmit the SSDV FSK signal. On the receive side they use an RTL-SDR dongle, low noise preamplifier and a GNU Radio program to demodulate the SSDV images. The first video below demonstrates the hardware and GNU Radio program and shows them receiving the SSDV signal. In the second video they demonstrate that the images can be received at low signal levels (-106dBm) as well, by heavily attenuating the signal.

115.2kbaud FSK Modem Test

115.387kbaud FSK Modem Test - Part 2

If you are interested, all their code for the SSDV system has been uploaded to https://github.com/projecthorus/HorusHighSpeed.

While testing the RTL-SDR for use in this system they also measured the noise figure of an R820T RTL-SDR dongle. The noise figure at maximum gain comes out at around 5.6 dB. By adding a low noise amplifier they reduce the measured noise figure down to 2 dB.

Testing the attenuated SSDV signal reception with an RTL-SDR.
Testing the attenuated SSDV signal reception with an RTL-SDR.

Listening to a Radio Amateur Stratosphere Balloon with an RTL-SDR

Over on YouTube user kpappa has uploaded a video showing his reception of the J43VHF radio amateur stratosphere balloon with an RTL-SDR dongle and discone antenna. On the 10th of May radio amateurs in Greece launched a high altitude balloon. The balloon carried a transceiver payload which allowed amateurs to talk to each other via the balloon at a frequency of 144.200 MHz. The video shows good reception of the balloon and also shows it’s tracking via APRS.fi.

More information about the balloon can be found at https://j43vhf.wordpress.com/ and http://hellashab.blogspot.gr/.

The high altitude balloon's radio payload recovered after landing.
The high altitude balloon’s radio payload recovered after landing.
Tracking J43VHF (Radio Amateur Stratosphere Balloon) by RTL-SDR & Diamond Discone D3000N Antenna

HackRF Decoding PICO High Altitude Balloons (HAB)

Blogger g0hww shows us how he used his HackRF to decode Pico high altitude balloon (HAB) transmissions using gqrx and dl-fldigi. Pico balloons are small party sized high altitude balloons, typically launched by hobbyists. They have enough lift to carry a small sized ~60g payload. Since they are so small, they are usually exempt from requiring permission from the authorities, unlike full sized weather balloons.

The cheaper RTL-SDR could also be used to track these balloons.

PICO High Altitude Ballo0n Recevied with HackRF

RTL-SDR Tutorial: Receiving Weather Balloon (Radiosonde) Data with RTL-SDR

Around the world meteorological weather balloons are launched twice daily, and continuously transit weather telemetry to a ground station using something called a radiosonde. The RTL-SDR software defined radio combined with a decoding program can be used to intercept this telemetry, and display it on your own computer. You will be able to see real time graphs and data of air temperature, humidity, pressure as well as the location and height of the balloon as it makes it's ascent.

Note that if you are in the USA, then this tutorial may not be applicable for you as different radiosondes are used. Instead have a look at this post which shows how to use the SkySonde software from NOAA. You can also try an alternative command line based decoder called RS available on GitHub.

This tutorial is also applicable to other software defined radios such as the Funcube dongle, Airspy, HackRF, BladeRF or even hardware radios with discriminator taps, but the RTL-SDR is the cheapest option that will work.


In this example YouTube user Superphish shows a radiosonde being received and decoded using a RTL-SDR, SDRSharp and SondeMonitor.

Weather Balloon (Radiosonde) tracking with RTL SDR (RTL2832), Sondemonitor and SDR Sharp

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