sorry, there is no direct way from DTS to AC3
One possible way is to decode your DTS(WAV) with a app called tranzcode to single WAVs then reencode (after upsampling 48KHz) to AC3.
Tranzcode(Mod) can be found on
needfulthings
CYA Daphy
Edit: DTSWAV can only decoded in the commandline mode -> the simple GUI canīt manage this -> see exaples in the readme