Hi folks, It has taken a little longer than I anticipated, but it's all here: http://wiki.spench.net/wiki/OP25 The page describes: . Getting the latest OP25 working with the latest GNU Radio (one easy patch) . Using the Legacy USRP shim so OP25 can access any USRP via UHD (one symlink) . How to do a side-by-side install of multiple OP25 versions <http://wiki.spench.net/wiki/Side-by-side_GNU_Radio_Modules> (one copy & script) . Adding DES-OFB decryption (a little more complex, but all the instructions are there) The side-by-side guide <http://wiki.spench.net/wiki/Side-by-side_GNU_Radio_Modules> not only applies to OP25, but any other GR module. Don't forget to install gr-baz <http://wiki.spench.net/wiki/gr-baz> to get the OP25 Decoder block <http://wiki.spench.net/wiki/gr-baz#op25> for GNU Radio Companion, a sample flowgraph that does the decoding from a variety of sources, the patches themselves and additional sample files. Please let me know if this is useful to people, what success you have, and if anyone is keen to move the DES-OFB code to the latest source (the patch is for version 219!). Kind regards, Balint