These are probably Chinese sky wave OTHRs (without a recording I cannot be sure). I don't know how often ya'll hear them there, but here on the west coast they are a curse every morning.
In the following picture there are at least 11 active, and maybe as many as 13, from about 5100 kHz to about 9150 kHz. These guys change frequency as needed, with no real "channels" as such, but they have typical ranges they fall in, for example 6800 to 7000 kHz is hammered most mornings. Note that there are 3 different waveforms in use by the ones in this picture, that is why they all do not look quite the same.

T!