But that's because there isn't a built ind DCF decoder that sends the data through RS232 like the GPS module.
You need to make your own decoder and this is the more complex part.
Btw, there are two types of DCF77 receivers: inverted and non-inverted output.
I hope the article will help you getting the DCF receiver to work

(Also, DCF77 is GMT +1)
Cheers