uhd: set hardware side delay offset for e100

The value is used to align transmit and receive time slots within
a sample. This oscilloscope measured value is close, but may
need minor tweaking.

Signed-off-by: Thomas Tsou <ttsou@vt.edu>

git-svn-id: http://wush.net/svn/range/software/public/openbts/trunk@2638 19bc5d8c-e614-43d4-8b26-e1612bc8e597
diff --git a/Transceiver52M/UHDDevice.cpp b/Transceiver52M/UHDDevice.cpp
index e134f56..145a15a 100644
--- a/Transceiver52M/UHDDevice.cpp
+++ b/Transceiver52M/UHDDevice.cpp
@@ -36,12 +36,13 @@
     rx_smpl_offset    - Timing correction in seconds between receive and
                         transmit timestamps. This value corrects for delays on
                         on the RF side of the timestamping point of the device.
+                        This value is generally empirically measured.
 
     smpl_buf_sz       - The receive sample buffer size in bytes. 
 */
 const bool use_ext_ref = false;
 const double master_clk_rt = 52e6;
-const double rx_smpl_offset = .00005;
+const double rx_smpl_offset = .0000869;
 const size_t smpl_buf_sz = (1 << 20);
 
 /** Timestamp conversion