JT9

JT9
Frequencies	3.578 MHz,28.079 MHz
Frequency Range	3.578 MHz - 28.079 MHz
Mode	USB
Modulation	MFSK
ACF	—
Emission Designator	—
Bandwidth	16 Hz,30 Hz,57 Hz,113 Hz,224 Hz,446 Hz,891 Hz,1.78 kHz
Location	Worldwide
Short Description	JT9 is a 9-FSK mode for making contact (QSO's) under extreme weak-signal conditions. It is part of the WSJT-X software.
I/Q Raw Recording	—
Audio Sample

JT9 is a 9-FSKFrequency-Shift Keying mode for making contacts (QSO's) under extreme weak-signal conditions. It is part of the WSJT-X software.

JT9 has eight submodes, JT9A to JT9H, with different tone spacings. The normal "slow" operating mode is primarily designed for weak-signal communications on HFHigh Frequency (3-30 MHz) and lower bands. 60-second transmit/receive slots are used. Transmission takes 49 seconds and the remaining 11 seconds are reserved for decoding and timing inaccuracies. Compared to JT65, the most common submode JT9A is about 1 dBThe decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, here the strength of a received signal. more sensitive while using less than 10% of the bandwidth.

Submodes JT9E to JT9H can also be operated in fast mode which is designed for meteor scatter and other propagation modes with short openings. In this mode, the messages are sent fast and repeated many times during the transmission window. The fast mode uses 5, 10, 15 or 30 second transmit/receive slots.

JT9 slow submodes
Submode	Tone spacing	Bandwidth	Minimum SNR for decoding
JT9A	1.74 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	15.6 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	-26 dBThe decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, here the strength of a received signal.
JT9B	3.47 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	29.5 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	-26 dBThe decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, here the strength of a received signal.
JT9C	6.94 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	57.3 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	-25 dBThe decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, here the strength of a received signal.
JT9D	13.9 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	113 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	-24 dBThe decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, here the strength of a received signal.
JT9E	27.8 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	224 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	-23 dBThe decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, here the strength of a received signal.
JT9F	55.6 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	446 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	-22 dBThe decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, here the strength of a received signal.
JT9G	111 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	891 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	-21 dBThe decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, here the strength of a received signal.
JT9H	222 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	1780 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	-20 dBThe decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, here the strength of a received signal.

The fast submodes use slightly more bandwidth than their slow counterparts. Duration of one cycle decreases with wider tone spacing - one JT9E fast cycle takes 3.4 seconds but one JT9H fast cycle takes only 0.425 seconds. These cycles are repeated over the transmit window.

Frequencies[edit]

3578-3579 kHzKiloHertz (kHz) 10^3 Hz
7078-7079 kHzKiloHertz (kHz) 10^3 Hz
14078-14079 kHzKiloHertz (kHz) 10^3 Hz
21078-21079 kHzKiloHertz (kHz) 10^3 Hz
28078-28079 kHzKiloHertz (kHz) 10^3 Hz

Samples - slow submodes[edit]

Showcase sample is JT9A. The following samples were recorded directly from WSJT-X with transmission frequency (tone) set to 1500 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). which is the default value. If you have samples of actual JT9 transmissions, please add them here!


JT9A	JT9B	JT9C	JT9D


JT9E	JT9F	JT9G	JT9H

Samples - fast submodes[edit]

The following samples were recorded directly from WSJT-X with transmission frequency (tone) set to 700 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). which is the default value for fast submodes. Transmit/receive window was set to 15 seconds. If you have samples of actual fast JT9 transmissions, please add them here!