HP's Digital Signal Processing (DSP) system is a transformerless design that combines a 3 stage power filtering system with a double conversion line adaptive UPS that delivers all of the benefits of double conversion technology without the waste & inefficiencies of on-line UPSs. True sine wave output is very important to the latest power factor correcting power supplies as they are designed to prevent bad power signals from damaging the server. The HP R5000 UPS also incorporates HP's enhanced battery management which can double the useful lives of the batteries saving, hundreds of dollars in the cost of ownership of the UPS.