I finally read the WSJT manual, quite quickly indeed, and from it I could gather the following:
"Encoded user information is transmitted during the 63 intervals not used for the sync tone. Each channel symbol generates a tone at frequency 1275.8 + 2.6917 Nm Hz, where N is the value of the six-bit symbol, 0 < N < 63, and m is 1, 2, or 4 for JT65 sub-modes A, B, or C. The signal report OOO is conveyed by reversing sync and data positions in the transmitted sequence. Shorthand messages dispense with the sync vector and use intervals of 1.486 s (16,384 samples) for the alternating tones. The lower frequency is always 1270.5 Hz, the same as that of the sync tone, and the frequency separation is 26.92 nm Hz with n = 2, 3, 4 for the messages RO, RRR, and 73." So, assuming N is the 63rd symbol in JT65A (m=1), it yields: 1275.8 + (2.6917 * 63) = 1275.8 + 169.5771 = 1445,3771 Hz The shift is less than 170 Hz !! And for 73: 1275.8 + (26.92 * 4) = 1275.8 + 107,68 = 1383,48 Hz The shift is 107,68 Hz! So, JT65A never occupies more than 170 Hz on the air, which is quite tolerable indeed. Figuring out all this, I wanted to corect my previous post. Yes, it is wider than PSK31, but not quite as wide as RTTY. 73, Jose, CO2JA PS: I have been monitoring quite a few QSO's on 7076 this evening! __________________________________________ V Conferencia Internacional de Energía Renovable, Ahorro de Energía y Educación Energética. 22 al 25 de mayo de 2007 Palacio de las Convenciones, Ciudad de la Habana, Cuba http://www.cujae.edu.cu/eventos/cier Participe en Universidad 2008. 11 al 15 de febrero del 2008. Palacio de las Convenciones, Ciudad de la Habana, Cuba http://www.universidad2008.cu
