Index

Spectrograms

Navigation

Spectrogram Interpretation

The Ionosphere and HF Propagation

Principles of Operation

GRAPE-1
GRAPE-2
WSPRDaemon GRAPE

Feature Spectrograms

Typical Spectrogram
Surface Wave
One-hop E region propagation
Sporadic E (Es)
One-hop F Region Propagation
Two Hop F Region Side Scatter
Prolonged Two Hop F Region Side Scatter
Dawn Doppler
Travelling Ionospheric Disturbance
SID and Doppler Flash
Solar Eclipse
BPM Time Signals
High and Low Rays

Event Spectrograms

Partial Eclipse 29 March 2025
Geomagnetic Storm 18 January 2026

Artifacts

Precision Local Oscillator

Resources

Event Template
Lexicon

Related Topics

Documentation overview

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