I've written a self-contained utility that, in one go, will generate an 'include' file for PIC assemblers for generating WSPR signals from a DDS. see http://www.g4jnt.com/beacons.htm and www.g4jnt.com/GENWSPR.EXE
Run GENWSPR from the command line and specify call, loc and power, for example 'genwspr g4jnt io90 43' and it will go away and generate a file WSPTONES.INC for importing into a PIC assembly file.
The actual WSPR encoding section is taken from a C listing I found on the web, but can't rememberer where or who to credit. That had mathematical errors in it relating to the Lat/Long conversions to WSPR source coding. Corrected these and added the rest.
Oh yes, and it will give you an audio file(.AU format) as well - left in from the original code.
Andy G4JNT
www.g4jnt.com