NIL HEARDRECEPTION LOG

VLF submarine band 17.6-20.0 kHz (RDL, HWU, GBZ chord)

tier A · keyed-tone

17.3 kHz USB · 2026-10-06 15:39:14Z · 10:00 · received at Heppen, Limburg, Belgium

Spectrogram of VLF submarine band 17.6-20.0 kHz (RDL, HWU, GBZ chord), 17.3 kHz USB, 2026-10-06 15:39:14Z, 10:00: keyed-tone 57% · carrier 33% · data 10% · tone 2651 Hz · keying 0.75 Hz depth 0.60
spectrogram 0–6.0 kHz · analysis blocks: keyed-tone data carrier
loop [ ] · speed in the player bar · deep link #t=seconds ⤓ FLAC 9.4 MB ⤓ Opus 2332 kB { }
What was heard
keyed-tone 57% · carrier 33% · data 10% · tone 2651 Hz · keying 0.75 Hz depth 0.60 — dominant tone 2651 Hz, keyed at 0.75 Hz (depth 0.6). Machine description of the sound by the rig's classifier; it sorts, it does not certify a station.
Receiver
KiwiSDR, Heppen, Limburg, Belgium (JO21oc) · Longwire 54m top 70m above sealevel · reported SNR 33 dB — thanks to the operator. Receivers
Provenance
sha256 f49936a2a005d253529f594cee0aae8aef8de8239e109c63186783eccb1382a0
source 10:00 WAV, 12000 Hz mono
kiwirecorder.py (jks-prv/kiwiclient v1.11) · rig item 2026-10-06T1539Z-17.3-vlf-17300
Heard in the record
— linked once the record exists.
Licence
CC BY 4.0 — credit NIL HEARD / Reception Log. The recording is ours; the transmission is somebody else's. Descriptions describe sound, never content — why.
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