CIS OFDM-121
 | |
|---|---|
| Frequencies | 4.454 MHz,20.866 MHz |
| Frequency Range | 4.454 MHz - 20.866 MHz |
| Mode | USB |
| Modulation | PSK4,OFDM |
| ACF | — |
| Emission Designator | — |
| Bandwidth | 3.1 kHz,2.7 kHz |
| Location | Russia |
| Short Description |
CIS OFDM-121 is an OFDM mode that uses OFDM bursts with 121 channels, spaced by two PSK4-like bursts. Not all of the 121 available channels of OFDM bursts are used and it's possible to note a different arrangement of the channels in different days. |
| I/Q Raw Recording | Download file |
| Audio Sample | |
CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 is an OFDMOrthogonal Frequency-Division Multiplexing mode that uses OFDMOrthogonal Frequency-Division Multiplexing bursts with 121 channels, spaced by two PSK4-like bursts. Not all of the 121 available channels of OFDMOrthogonal Frequency-Division Multiplexing bursts are used and it's possible to note a different arrangement of the channels in different days.
Sometimes CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 transmission has only PSK4-like bursts without OFDMOrthogonal Frequency-Division Multiplexing bursts, in such cases the PSK4-like bursts are being transmitted in pairs (two PSK4-like bursts, transmitted one after another), similar to regular transmission, the timing between transmission of each pair might be the same as during normal transmission with OFDMOrthogonal Frequency-Division Multiplexing bursts (long-spaced idle) or shorter (short-spaced idle). The transmissions without OFDMOrthogonal Frequency-Division Multiplexing bursts could mean that no traffic is being sent and CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 is in an idle state.
It was noticed that regular transmission (with OFDMOrthogonal Frequency-Division Multiplexing bursts) sometimes can have gaps - no OFDMOrthogonal Frequency-Division Multiplexing burst is being transmitted, despite OFDMOrthogonal Frequency-Division Multiplexing bursts were transmitted before and after the gap. There might be several gaps during the transmission, but in that case there should be at least one OFDMOrthogonal Frequency-Division Multiplexing burst before and after each gap (there might be two gaps in a row, but that's very rare). Sometimes PSK4-like bursts might be transmitted one after another not in pairs up to 15 bursts in a row.
The origin of the signal is assumed to be Moscow, Russia.
Samples[edit]
Long signal recordings:
USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 regular transmission with OFDMOrthogonal Frequency-Division Multiplexing bursts:
USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 idle state:
Pairs of PSK4-like bursts with short transmission timing
Pairs of PSK4-like bursts with long transmission timing
Frequencies[edit]
The signal was noticed on frequencies from 4.454 MHzMegaHertz (MHz) 10^6 Hz up to 20.866 MHzMegaHertz (MHz) 10^6 Hz.
List of frequencies:
| Frequency | Verification |
|---|---|
| 20.866 MHzMegaHertz (MHz) 10^6 Hz | Observed several times. |
| 20.386 MHzMegaHertz (MHz) 10^6 Hz | Observed several times. |
| 19.870 MHzMegaHertz (MHz) 10^6 Hz | Observed one time. |
| 14.462 MHzMegaHertz (MHz) 10^6 Hz | Observed one time. |
| 13.382 MHzMegaHertz (MHz) 10^6 Hz | Observed several times. Observed by at least two people at different time and recieved in different locations |
| 11.087 MHzMegaHertz (MHz) 10^6 Hz | Observed one time. |
| 10.843 MHzMegaHertz (MHz) 10^6 Hz | Observed one time. |
| 9.240 MHzMegaHertz (MHz) 10^6 Hz | Observed several times. |
| 9.077 MHzMegaHertz (MHz) 10^6 Hz | Observed several times. |
| 8.071 MHzMegaHertz (MHz) 10^6 Hz | Observed several times. |
| 6.878 MHzMegaHertz (MHz) 10^6 Hz | Observed several times. |
| 5.112 MHzMegaHertz (MHz) 10^6 Hz | Observed several times. |
| 4.454 MHzMegaHertz (MHz) 10^6 Hz | Observed one time. |
Sometimes the frequency of transmission can suddenly change onto nearby frequency within 20 kHzKiloHertz (kHz) 10^3 Hz, but such hops are presumably rare.
It was noticed that CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 transmitted eight repetitions in idle state (eight pairs of PSK4-like bursts) on several frequencies across HFHigh Frequency (3-30 MHz) spectrum, one after another, from the lowest frequency to the highest, and then again and again for at least an hour and a half. It may be assumed that this is a sounding across several channels.
Video Examples[edit]
https://www.youtube.com/watch?v=OryYKB61iys
https://drive.google.com/file/d/1xGS-7eF0ZV60Is9XpsXYsA7kQhID2WRm/view?usp=sharing
Additional Links[edit]
CIS OFDM-121 system on diario SWL I-56578 Antonio
Additional Images[edit]
CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 on 20.386 MHzMegaHertz (MHz) 10^6 Hz
CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 on 20.386 MHzMegaHertz (MHz) 10^6 Hz
CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 on 20.866 MHzMegaHertz (MHz) 10^6 Hz (up close)
CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 up close
CISCommonwealth of Independent States (CIS), the former Soviet Republic OFDMOrthogonal Frequency-Division Multiplexing-121 sounding in short-spaced idle state on 9.077 MHzMegaHertz (MHz) 10^6 Hz
