Hi Jock, go to the Uniden forums, Uniden tech support and you will find several simultaneous threads regarding the new firmware update for the 100 and 200 that you get directly from Uniden Sentinel for free.
You need to install this new firmware update before you can purchase, for $20, the waterfall upgrade from Uniden website. There are a number of photos and explanations of the waterfall feature in those threads.
I'm not your guy to describe any of it, as due to the feedback on these threads, I have chosen not to install the firmware updates at this time and I personally have little interest in the waterfall feature. 73s.. Bob.