console's b360#2 15meters band blocked


HI , this morning I have played SWL_ing in the IOTA contest and when I have switched on 15meters the thing you see in the pic below happened :

The strong signal is a friend's ssb playing in the IOTA-ssb away from me about 1Km.
The strenght was about S9+20.
When He was transmitting the whole RX window and hence the weak signals around him disappeared.
At the end of the transmission there is a Black_Hole GAP before the signals around come again visible.

Could not test on 10 meters, but on 20 and 40 meters it did not happen.

I Have tried in the afternoon to feed a strong carrier about S8-9 from my RF_Gen in the SDR_IQ and "seems" also happening the same thing.

Such bad blocking occours only in very cheap\poor hardware radios, here is all software.
What do you think Simon ?