24 December, 2017

FT8 anomaly or long delayed echo?

My friend Alf, LA2NTA, has sent me these screenshots from when he has been operating FT8. The first image is when operating 10 meters and took place early in November.

Two of LA2NTA CQs being received by himself on 10 meter (in red)

It shows how his own CQ comes back to him at 10.54.00 and at 11.00.00 and is decoded in his own receiver. The echoes return at the time of transmission.

The second example is from 20 meters and took place just a few days ago.

LA2NTA CQ being received by himself on 20 meter (in red)

For the first example he also took an image of the spectral display. It shows lots of repeated noise burst all over the FT8 band.

FT8 band on 10 meters showing some form of noise all over the band

It is hard to explain this, but my hunch is that it is something local and not a propagation phenomenon, but who knows?