https://www.cyberpowersystems.com/product/ups/cp1500pfclcd/
I want this unit but after reading this post
When do I need a pure sine wave UPS?
Im a bit nervous on spending this much when I don't really know what Im getting. I don't understand enough about power to make an informed decision. Im looking for a ups for a high end gaming pc if that matters.
As outlined in the accepted answer to the question you linked... you'll probably be fine with a cheap UPS.
The CP1500PFCLCD states that the waveform is "Sine Wave", so you're probably a bit better than fine.
The big thing you should focus on is the power - you state that this is for a "High-End gaming PC". Depending on what you actually mean by this, it's possible / likely that the 900W rating will not be enough. (what is your PC's power supply rated for?)
You should never run a UPS over it's rated wattage, even if you are currently "on mains" - many will forcibly shutdown in this situation.
How do I get an Oscillogram for this UPS?
By using an Oscilloscope - a piece of electronics lab equipment that allows inspection of analog signals, typically plotted against time. A second hand analog scope can usually be found on eBay for as little as £30.
Lastly, please note that hardware recommendations and shopping advice are off topic here.
