I might be guessing here .... but, I was under the impression that 200kHz is a 2d sonar ping and 455kHz is a DI sonar ping. I wouldn't think a 2d processor could even interpret a 455kHz signal, or a DI interpret a 200kHz signal.
From what I've read about this unit ... the 2d imaging is done with a dual beam 83/200kHz signal ... and the DI is done with a 455kHz signal. It is capable of split screen images, either the two 2d signals or the 2d & DI signals. What I don't understand is how you can choose the 455kHz signal for the 2d imaging ..... shouldn't the kHz signal automatically relate to whichever imaging view (2d or DI) that you choose ??
... cp