Old Document but indeed helpful!
Thats the one I always supply my guys. But I've always had trouble with SCP when connecting to third party SCP servers. I've always had good luck using a simple HTTP file server like HFS.
They all re-image the same from the FMC to 7X and 8x devices. If you run into trouble with SCP when you attempt to download the image file, try using HFS file server, its a simple and free HTTP file server that has never failed me. I host the image files in the US and have no issues having sensors connected and download from around the world.