What Protocol Is This?

[VK2JDS]

I apologise for the slowness of my reply.

Thanks for the hints and ideas.

At one stage, over the weekend, I noticed that one of these signals repeated five times across the waterfall (in the same 15 second segment).  All were equally spaced, which I guess leans towards an over driven signal with lots of spurious artefacts.

I have observed his effect on JT65 on moonbounce. An Alaskan station's signal was appearing several times up the band on 1296 every time he transmitted.
After i explained what i was seeing he tracked it down to the external 10 MHz gps reference that feeds his XREF type of pll that locked the master oscillator in his radio.
The filter capacitor in the power supply had gone open circuit and the supply to the oscillator had ripple on it, which was modulating the 10 MHz output. 
The clue being that the spacing between the multiple outputs was exact and repeatable, indicating a problem with the radio's synthesiser rather than an overdrive fault. A new capacitor fixed it.
73 Dave vk2jds