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| author | Tom Tsou <tom@tsou.cc> | 2015-01-08 11:53:23 -0800 |
|---|---|---|
| committer | Martin Braun <martin.braun@ettus.com> | 2015-01-12 10:54:09 +0100 |
| commit | 2a54f8e291ded149268542a1fa23e870106d7e4b (patch) | |
| tree | ce42021686cb8fdf842baeaadc6129140a9f5bb3 | |
| parent | 6460ac1c3c3bf82e16f70dadff5e01211832c3ed (diff) | |
| download | uhd-2a54f8e291ded149268542a1fa23e870106d7e4b.tar.gz uhd-2a54f8e291ded149268542a1fa23e870106d7e4b.tar.bz2 uhd-2a54f8e291ded149268542a1fa23e870106d7e4b.zip | |
convert: Fix sc12 unpack shifting
Resolve issue #666 "B200: Rx signal distortion when using SC12".
During 12-bit unpacking, OTW samples are shifted into the high order
bits of the 16-bit intermediate values. The remaining 4-bits are not
zeroed and contain bits from adjacent samples. Consequently, signal
distortion becomes noticable with spurs and other random signal
garbage when operating at low signal levels.
Signed-off-by: Tom Tsou <tom@tsou.cc>
| -rw-r--r-- | host/lib/convert/convert_unpack_sc12.cpp | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/host/lib/convert/convert_unpack_sc12.cpp b/host/lib/convert/convert_unpack_sc12.cpp index a2aec2ae5..94b415355 100644 --- a/host/lib/convert/convert_unpack_sc12.cpp +++ b/host/lib/convert/convert_unpack_sc12.cpp @@ -62,17 +62,17 @@ void convert_sc12_item32_3_to_star_4 const boost::uint64_t line12 = (boost::uint64_t(line1) << 32) | line2; //step 1: shift out and mask off the individual numbers - const type i0 = type(boost::int16_t(line0 >> 16)*scalar); - const type q0 = type(boost::int16_t(line0 >> 4)*scalar); + const type i0 = type(boost::int16_t((line0 >> 16) & 0xfff0)*scalar); + const type q0 = type(boost::int16_t((line0 >> 4) & 0xfff0)*scalar); - const type i1 = type(boost::int16_t(line01 >> 24)*scalar); - const type q1 = type(boost::int16_t(line1 >> 12)*scalar); + const type i1 = type(boost::int16_t((line01 >> 24) & 0xfff0)*scalar); + const type q1 = type(boost::int16_t((line1 >> 12) & 0xfff0)*scalar); - const type i2 = type(boost::int16_t(line1 >> 0)*scalar); - const type q2 = type(boost::int16_t(line12 >> 20)*scalar); + const type i2 = type(boost::int16_t((line1 >> 0) & 0xfff0)*scalar); + const type q2 = type(boost::int16_t((line12 >> 20) & 0xfff0)*scalar); - const type i3 = type(boost::int16_t(line2 >> 8)*scalar); - const type q3 = type(boost::int16_t(line2 << 4)*scalar); + const type i3 = type(boost::int16_t((line2 >> 8) & 0xfff0)*scalar); + const type q3 = type(boost::int16_t((line2 << 4) & 0xfff0)*scalar); //step 2: load the outputs out0 = std::complex<type>(i0, q0); |