GRAVES · 143.050 MHz · KN09VW
How the receiving station works
One narrow VHF channel passes through a dedicated receiving chain, a non-blocking IQ transport and a reproducible analysis pipeline before it reaches the public archive.
FORWARD SCATTER
Radar, ionised trail, receiver
GRAVES transmits a strong continuous signal in France. A suitably placed ionised trail can scatter part of that signal toward the SO8OO station in south-eastern Poland. As the trail forms and disperses, the returned carrier changes in strength, duration and frequency structure.
RF AND SDR
A narrow, protected 2 m signal path
- Directional VHF antenna collects the 143 MHz illumination from the useful geometry.
- External filtering and preamplification rejects strong out-of-band energy before the sensitive receiver input.
- SDRplay RSPduo samples the VHF spectrum and supplies the dedicated GRAVES channel.
- Digital down-conversion produces 16-bit complex samples at 32 kS/s around 143.050 MHz.
DETECTION AND PUBLICATION
From complex samples to a browsable record
A bounded, non-blocking IQ tap carries the GRAVES channel to the analysis host without being allowed to stall the receiver. A fixed FFT produces the waterfall, detector measurements and peak frequency from the same samples. UTC timing is retained throughout the chain.
When the detector opens an event, the recorder preserves context from before and after the trigger. Public products include an interactive waterfall, synchronised audio and selected metadata. The recorder operates independently of scheduled YouTube streams.
FURTHER READING