"The last LORAN C receiver: SDR"

http://phk.freebsd.dk/loran-c/

Seems like a natural hack for the USRP. He (Poul-Henning Kamp) had to
use a PCI card at the time (2003).

He claims it’s un-jammable and similar in resolution to GPS; see the
“LORAN-C politics” section.

John