Redesign and Performance Evaluation of a Narrow-Band FM Demodulator and Decoder for Radiosonde Telemetry
Johannes Frielingsdorf
MA Thesis. Technische Hochschule Köln, 2021.
Keywords
Graw DFM Vaisala RS41 Radiosonde Telemetry Baseband Decoder Narrowband-FM FSK Squaring Loop Correlation Decoder
This work relates to the redesign and performance evaluation of baseband decoders for Graw DFM model radiosonde telemetry.
Radiosondes are instruments used to measure upper-air meteorologic data, which is sent to the ground using a radio transmission. The DFM radiosonde transmission protocol was revolutionary when introduced first, but does not use the transmission channel very efficiently.
Ham radio operators are actively developing and optimizing Telemetry receivers, while Graw still uses a classic approach. Baseband decoders have been implemented based on the approaches used by Graw and ham radio operators. The approach used by ham radio operators has many implementation advantages and outperforms Graws. Telemetry quality still could be optimized by a different receiver architecture and telemetry protocol.
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- Scope of Work
- Radiosondes as Meteorological Instruments
- Use Cases for Radiosondes
- Market Overview
- Radiosonde Hardware
- Legacy of the Graw DFM Family
- Graw DFM-17 Hardware
- Radiosonde Telemetry
- Measurements of upper wind with weather balloons and radiosondes
- Regulations and General Considerations
- FSK-Modulation
- Radiosonde PTU Telemetry
- Graw DFM Telemetry
- Manchester Line Code
- Frame Composition
- Deinterleaving and Error correction
- Accumulating a complete Data Set
- Comparison to Vaisala RS41 Telemetry
- Radio Receiver Fundamentals
- Superhetrodyne Receivers
- PLL FM demodulation
- Software Defined Radio
- Implementations of Radiosonde Telemetry Receivers
- Graw GS-E Ground Station
- Antennas and Antenna Control
- Winradio WR-G305e Receiver
- DSPSW Software Module
- Further Data Processing
- Radiosonde Auto-RX Tracker
- RTL-SDR Receiver
- rs1729 RS Decoder
- Auto RX Tools
- Graw GS-E Ground Station
- Developed Baseband Decoders
- DFM Codec
- Baseband Simulator
- Squaring Loop Decoder
- Squaring Process
- Quantization and DPLL Process
- Symbol detection
- Header Decision
- Header Correlation Decoder
- Precalculated Symbol Masks
- Header Correlation and Peak Finding
- Symbol Decision
- Chunked Processing
- Comparison of the Algorithms
- Baseband Decoder Performance
- General Approach
- Measurement Parameter Definition
- Performance Evaluation
- Significance of Measurement Priciples used
- Conclusion
- Appendix A: Detailed Breakdown of DFM Telemetry Decoding
- How to obtain (G)FSK Data in general
- How to get from Audio to Data
- General considerations regarding Graw DFM Telemetry
- Manchester-Decoding
- Frame Composition
- Deinterleaving
- Hamming Error Correction
- From a Frame to a Data Packet
- List of Acronyms
- List of Figures
- List of Tables
- Bibliography