What Protocol Is This?

[VK2CSW]

Hi All,

I quite often see the highlighted signals on my waterfall while using FT-8.

There can be several of them spread over the waterfall.

   

Any ideas what it is?

[VK3LU]

Hi Colin,
Could it be Olivia? Just a guess as it has eight components.

Nev

[VK4YMB]

Hi Colin,
I have seen similar signals when using both FT8 and JT65, to me they look like expanded 'birdies' or 'harmonics' from strong signals some where lower in frequency - on your image, possibly at ~ 630hz. This was most evident when using JT65, as with its wider signal width I could see the individual element pattern being reflected further up the waterfall.

The cause, maybe over-driven/over-modulated TX signal, or some interaction in the receive path, they always seem (to me anyway) to be associated with strong signals.

Just my observations on the signals.

73 Andrew

[VK3RX]

Looks like one of the Hellschreiber modes.

What does it sound like?

Check here for how the various modes look and sound:

Sounds & Spectra

[VK5PJ]

Hi Colin, it is a product from another FT8 user who is whacking their ALC pretty hard, have seen it before on local VHF FT8 and asked the OP to lower drive and funny signal went away.

Peter, vk5pj

[VK2CSW]

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.

[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