Chinese 30-tone OFDM modem
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|---|---|
| Frequencies | 3.618 MHz,18.656 MHz |
| Frequency Range | 3.618 MHz - 18.656 MHz |
| Mode | LSB, USB |
| Modulation | QPSK,BPSK,OFDM |
| ACF | — |
| Emission Designator | — |
| Bandwidth | 3 kHz |
| Location | China, Worldwide |
| Short Description | A 30-tone OFDM data mode, probably used by Chinese military or other agencies. |
| I/Q Raw Recording | — |
| Audio Sample | |
This is a 30-tone OFDMOrthogonal Frequency-Division Multiplexing data mode that is believed to be used by Chinese military or other agencies.
The signal is transmitted in bursts, apparently in LSBLower Side Band Modulation mode (occasionally in USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)), and there is a pilot tone at approximately 445 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).. Each burst starts with a preamble of 4 tones, spaced 600 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). apart, first at about 650 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz)., modulated in QPSKQuadrature Phase-Shift Keying (2 bits per symbol). Actual data transmission happens with 30 OFDMOrthogonal Frequency-Division Multiplexing tones, each BPSKBinary Phase-Shift Keying (1 bit per symbol) modulated. Bandwidth of the signal is approximately 3 kHzKiloHertz (kHz) 10^3 Hz.
Samples[edit]
| Short bursts | Short bursts, possibly idling |
Possible traffic | USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) Transmission |
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Frequencies[edit]
Frequency range is not well known but it has a massive amount of transmissions on the HFHigh Frequency (3-30 MHz) band. 80 unique frequencies have been found, ranging from 3618 kHzKiloHertz (kHz) 10^3 Hz to 18656 kHzKiloHertz (kHz) 10^3 Hz.
Video Examples[edit]
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