With tones unless you know the exact digital mode, and what to expect each tone frequency to be, you cannot tell if a signal is USB or LSB. In this case it is USB. The frequency is 10139 kHz, USB, and the mode is JT65 (WJST). The range of 10139 to 10141 kHz is recognized WSPR/JT65/WJST section of the band. This means you will find users anyplace from 10139 to 10141 kHz using this mode.
I am looking at that section of the band right now, I see at least 6 stations between 10139 and 10141 kHz as well as one user on a c/f of 10138.8 kHz.
The cycle you are hearing is the listen/talk cycle of stations. They transmit for a while and then listen for a while, in predetermined time windows.
Like I said, 30 meter ham band, digital modes, WSPR/JT65/WJST. You will hear it all day long.
Information here:
http://hflink.com/jt65/http://en.wikipedia.org/wiki/WSJT_(Amateur_radio_software)
T!
(edit) typo road repair