Russian military 20bd 7kHz FSK
 | |
|---|---|
| Frequencies | 7.041 MHz,7.0625 MHz,7.0425 MHz,7.061 MHz,6.941 MHz,6.9425 MHz,6.961 MHz,6.9625 MHz |
| Frequency Range | 6.941 MHz - 7.0625 MHz |
| Mode | USB |
| Modulation | FSK |
| ACF | — |
| Emission Designator | — |
| Bandwidth | 7 kHz |
| Location | Russia |
| Short Description | Slow 20-baud FSK signal with very large 7 kHz frequency shift. Used by Russian military. |
| I/Q Raw Recording | — |
| Audio Sample | |
This is a slow 20-baudBaud (unit symbol Bd) is the unit for symbol rate or modulation rate in symbols per second. FSKFrequency-Shift Keying mode used by Russian military, with unusual 7 kHzKiloHertz (kHz) 10^3 Hz frequency shift. Due to such a large frequency shift, it may be confused as being two CW transmissions on nearby frequencies. Transmissions have been heard since December of 2025 on the 40-meter amateur radio band, usually but not always, on two frequencies simultaneously.
At least one source of the signal has been traced to Crimea, close to Sevastopol, where the Russian Black Sea Fleet base is located.
Samples[edit]
| Another sample with some faint humm radio talk between the two frequencies |
|---|
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Both samples contain the same repeating 255 bits :
0000000000010001101100101001100110111001111000000001101101011101100001100101001000101100000101011001
1000111101011011000101111111100111011110011110010001110111111110111110100000101010001010101100001011
1110010110000100111010011110101111101111011010111111011
Frequencies[edit]
Usually the 7kHz FSKFrequency-Shift Keying is being transmitted on two frequencies simultaneously, and two such frequency pairs have been identified. "Pair 1" seems to be more commonly used.
| USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) tuning freq | Lower tone | Upper tone | Center freq |
|---|---|---|---|
| 7041 | 7041.5 | 7048.5 | 7045 |
| 7062.5 | 7063 | 7070 | 7066.5 |
| USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) tuning freq | Lower tone | Upper tone | Center freq |
|---|---|---|---|
| 7042.5 | 7043 | 7050 | 7046.5 |
| 7061 | 7061.5 | 7068.5 | 7065 |
As of May 2026, new frequency pairs have been observed. The frequencies may have been changed to reduce interference from amateur radio transmissions.
| USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) tuning freq | Lower tone | Upper tone | Center freq |
|---|---|---|---|
| 6941 | 6941.5 | 6948.5 | 6945 |
| 6962.5 | 6963 | 6970 | 6966.5 |
| USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) tuning freq | Lower tone | Upper tone | Center freq |
|---|---|---|---|
| 6942.5 | 6943 | 6950 | 6946.5 |
| 6961 | 6961.5 | 6968.5 | 6965 |
Other frequencies may also be used but this was not been confirmed.
The transmissions repeatedly switch from frequency pair 1 to pair 2 and then back to pair 1 with regular time intervals:
when switched to pair 1 (6941.5 kHzKiloHertz (kHz) 10^3 Hz, 6948.5 kHzKiloHertz (kHz) 10^3 Hz and 6963 kHzKiloHertz (kHz) 10^3 Hz, 6970 kHzKiloHertz (kHz) 10^3 Hz) the transmission will switch to pair 2 after 20 minutes,
when switched to pair 2 (6943 kHzKiloHertz (kHz) 10^3 Hz, 6950 kHzKiloHertz (kHz) 10^3 Hz and 6961.5 kHzKiloHertz (kHz) 10^3 Hz, 6968.5 kHzKiloHertz (kHz) 10^3 Hz) the transmission will switch back to pair 1 after 10 minutes.
Example:
| Time (UTC) | Lower tone (1st transmission) | Upper tone (1st transmission) | Lower tone (2nd transmission) | Upper tone (2nd transmission) |
|---|---|---|---|---|
| 22:20 | 6943 | 6950 | 6961.5 | 6968.5 |
| 22:30 | 6941.5 | 6948.5 | 6963 | 6970 |
| 22:50 | 6943 | 6950 | 6961.5 | 6968.5 |
| 23:00 | 6941.5 | 6948.5 | 6963 | 6970 |
| 23:20 | 6943 | 6950 | 6961.5 | 6968.5 |
| 23:30 | 6941.5 | 6948.5 | 6963 | 6970 |
| 23:50 | 6943 | 6950 | 6961.5 | 6968.5 |
| 00:00 | 6941.5 | 6948.5 | 6963 | 6970 |
When switching from one frequency pair to another, the transmissions change their frequency instantly, but not at the same time. It was noticed that FSKFrequency-Shift Keying signal on lower frequency switches first, FSKFrequency-Shift Keying signal on higher frequency switches after a little delay.
Video Examples[edit]
- Signal Phantom: Russian Navy Intruder Wide FSK Signals Re-Appear on 40m Band
- Signal Phantom: Russian Navy Wide FSK Intruder Reappears On 40m Band | Signal Phantom
Additional Links[edit]
- "CIS 20Bd/7000 Wide FSK" I56578 blog
- "Some weird CW found on 40m" on SOTA Reflector
- "RTTY with 7kHz shift on 7.045 and 7.066?" on r/signalidentification
Additional Images[edit]
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