Is pulse chain on Ethereum?

Excuse me, I was just reading about the pulse chain and I was wondering if it's actually built on the Ethereum blockchain? I understand that it's a fork of the Ethereum network, but does that mean it operates directly on the Ethereum blockchain, or does it have its own separate network? I'm trying to get a better understanding of how pulse chain functions and where it fits in the cryptocurrency landscape. Any clarification you can provide would be greatly appreciated.