Improving the Listening Experience for SSB-Modulated HF Transmissions Using Neural Networks / von M.Sc. Jens Heitkämper ; Erster Gutachter: Prof. Dr.-Ing. Reinhold Häb-Umbach, Zweiter Gutachter: Prof. Dr.-Ing. Gerhard Schmidt. Paderborn, 2023
Content
Abstract
Acknowledgments
Introduction
High Frequency Radio Transmission
Related Work
High Frequency Radio Database
Transmission
Clean signal design
Data preparation
Marker detection
Post-processing
Database
IQ Recordings
Concurrent speakers
Simulating high frequency radio signals
Summary
Speech Activity Detection
Architecture
Segment recurrent neural network
Cost function
Baseline
Evaluation
SAD on optimally demodulated speech
SAD on recordings with concurrent speakers
SAD on frequency shifted speech
SAD on IQ signals
Summary
Carrier Frequency Offset Estimation and Correction
RAKE estimator
NN-based estimators
CFO correction
Evaluation
Database
Performance measures
NN parameter tuning
CFO estimation
CFO estimation on IQ signals
CFO correction
Summary
Speech Enhancement
System overview
Encoder and decoder
Mask estimator
Cost function
Evaluation
Database
Evaluation Measure
Top- and baseline
Source separation
Noise reduction
Noise reduction on an unseen language
Summary
Multi-Stage Processing
Evaluation of the enhancement stage
Performance measure for imperfect activity information
Evaluation of the multi-stage system
Impact of an unseen language
Summary
Conclusion and Outlook
Appendix
Analysis of the delay correction on the recording
Comparison of real to simulated training data ratios
Evaluation on Russian data with a CFO
CFO estimation on overlapping speakers
Enhancement with oracle masks
Small encoder and decoder windows for NR on real HF signals
Evaluation of noise reduction on signals with a CFO
Acronyms
Bibliography