Radiosonda

Stratospheric Balloon Wireless Transmission Analysis

This repository contains the source code and documentation of ours engineering thesis project: “Analysis of Wireless Transmission Media Using a Stratospheric Balloon”, developed at WSB Merito University in Poznań as part of the requirements for obtaining the degree of Engineer in Computer Science. The project was implemented in C++.

Project Goal

The main objective of this project was to design, build, and launch a stratospheric radiosonde equipped with multiple radio transmitters in order to analyze different wireless transmission technologies under extreme atmospheric conditions.

The research focused on:

• Determining the altitude at which full communication with the balloon is lost depending on the chosen technology,

• Measuring packet loss rates across different transmission methods,

• Evaluating how combining multiple technologies can improve overall transmission reliability.

• Identifying which of the selected transmission methods (APRS, FT8, CW, FSQ2, FSQ6, LoRa) proved to be the most effective under stratospheric conditions.

• This study contributes to the development of more reliable and efficient communication systems for future stratospheric missions and telemetry systems.

Hardware Overview

The radiosonde payload was designed and built using dedicated hardware modules selected for their stability, compatibility, and reliability under stratospheric conditions:

• DRA818V (VHF transceiver) Used for APRS transmission in the 134–174 MHz band with FM modulation. Its low power output (0.5–1W) and VHF coverage made it suitable for our use.

• Si5351A (frequency generator) Provided precise frequency generation (8 kHz – 160 MHz) for CW, FT8, and FSQ transmissions. It was chosen for its VHF band coverage.

• VPDIGI (STM32-based AFSK1200 modem) Responsible for generating and handling AFSK1200 signals, essential for APRS. Selected due to its proven stability and UART-based communication.

• RYLR998 (LoRa SX1267 module) Supported LoRa transmissions in the 820–960 MHz band. This module was chosen for its excellent range-to-power efficiency ratio and easy AT-command control via UART.

• SIM800L (GSM module) Configured to send an SMS with GPS location as backup communication in case of failure of other radio systems. Its role as a backup ensured higher mission reliability.

• uBlox NEO-7N (GPS/GLONASS module) Provided accurate real-time positioning. GLONASS support ensured redundancy against GPS-only systems.

• Power Supply – Samsung INR18650-35E Li-Ion Cells Two high-capacity (3500 mAh) cells connected in series to deliver 8.4V. These batteries were selected for their temperature tolerance down to –10°C, crucial in stratospheric conditions.

• Step-Up & Step-Down Voltage Converters Step-up converter stabilized supply voltage at 12V, compensating for natural voltage drops as batteries discharged. Step-down converters regulated outputs to 3.3V, 4V, and 5V, ensuring proper operation of all modules.

The payload was enclosed in a 3D-printed insulated casing, designed in compliance with the CubeSat U2 standard. This ensured structural rigidity, modularity, and compatibility with common aerospace practices, while also providing resistance to low temperatures and reduced atmospheric pressure encountered in the stratosphere. To guarantee safe recovery, the system was additionally equipped with a parachute-based landing mechanism.

Ground support was provided by a custom-built Linux-based ground station with RTL-SDR receivers, SDR++ software, and decoding scripts.

Project Assumptions

The project was carried out in three main phases:

Preparation Phase (20 months)

Hardware and software design, prototyping, integration, and legal preparations for the flight.

Flight Phase (1 day)

Balloon launch to 32 km altitude, live communication tests, signal reception, and payload recovery.

Analysis Phase (12 days)

Data extraction from microSD and decoding logs, statistical evaluation of transmission reliability, and documentation of results.

The scope of the research targeted:

• Radio amateurs interested in building radiosondes,

• Students and researchers working on stratospheric or communication-related projects.

Results & Conclusions

Each technology demonstrated different levels of reliability, packet loss, and coverage range.

FT8, FSQ and LoRa showed the most consistent performance across altitude ranges, making them strong candidates for long-range telemetry.

The mission provided valuable insights into communication challenges in the stratosphere, supporting the design of future balloon and telemetry systems.

More detailed information can be found in the attached in repo engineering thesis - Engineering thesis

Project Gallery

Below are selected photos from the development and launch of the stratospheric radiosonde.

Each image illustrates a key stage of the project:

• The first photo shows the final pre-launch preparation of the balloon and payload.
• The second photo presents the internal layout of the radiosonde electronics, emphasizing the modular CubeSat-inspired design and sensor integration.

Technologies Used

• Programming Language: C++

• Radiosonde Hardware: Arduino Mega 2560 Mini, MS5611, DS3231, DRA818V, Si5351B, VPDigi, RYRL998, SIM800L, uBlox NEO-7N

• Ground Station hardware: Few x86 computers, Raspberry Pi 3B+, RTL-SDR v4 and V3, LilyGO TTGO V1.3, RYLR998

• Ground Station Software: SDR++, WSJTX, FL-Digi, Multimon-ng

• Radio Protocols Tested: APRS, FT8, CW, FSQ2, FSQ6, LoRa