| Archive ID: | RS-0412 / UVB76-611014 |
| Station: | UVB-76 (pre-standard variant — designation approximate) |
| Date / Time: | 14 October 1961, 21:47:03–21:48:47 UTC |
| Frequency: | 1420.405 MHz (neutral hydrogen line) |
| Duration: | 1 min 04 sec (47s active + 17s noise decay) |
| Donated by: | Anonymous — received by post, Novosibirsk postmark, 2019 |
| Original format: | Magnetic tape (Slavit-6 reel), 4-track mono, 9.5 cm/s |
| Digitised by: | K7RXQ, 2019 |
The spectrogram below renders the recording's frequency content over time. X-axis = time (0–64 seconds). Y-axis = frequency (1400–1440 MHz range, normalised). Brightness = signal intensity. Use the brightness slider to adjust visibility. Look carefully.
Several community members have noted that something appears to be encoded in the signal envelope. The structure visible in the spectrogram does not resemble thermal noise or any known natural emission pattern at this frequency.
Forum user DX_Wanderer was the first to notice, in January 2024: the signal envelope in the spectrogram, when viewed at high brightness, resolves into distinct on/off pulses consistent with Morse code. The pulses are embedded in the carrier wave amplitude — not the frequency — and span the full 47-second active window.
Turn the brightness up to maximum and look at the bright central band. You should be able to read the dots and dashes directly, or use the Morse decoder below.
The Morse string as identified by the community analysis:
Use the decoder below to translate this Morse to text. Enter the dots and dashes, or paste the string above.
Enter Morse code (dots and dashes, space between letters, / between words):
> Decoder ready.
> Awaiting input.
▶ SIGNAL DECODED
The Morse string decodes to:
GRAVURE STARFALL OPEN
This appears to be an access code. The words GRAVURE and STARFALL appear in a declassified CIA document index from the mid-1960s, but the relevant files remain classified. One site has apparently obtained those documents.