Andre,
to make the USRP work, you will have had to enter a device string. Few of us will have access to an N210, but there is extensive documentation on the ettus website. This page may (or may not) be what you need:
http://files.ettus.com/manual/page_usrp2.html
There is mention there of sc16 and sc8. Note that
the 8 bit samples have a much reduced dynamic range
compared to 16 bit samples. Having skimmed the website I feel your
pain! http://files.ettus.com/manual/structuhd_1_1stream__args__t.html
is a good example (though definitely not the worst) of why
programmers, head-case or otherwise, should generally get someone
else to document the interface! That said, the section std::string
uhd::stream_args_t::otw_format finally discloses the
information that you almost certainly need!
Good luck,
Robin, G8DQX
.