[Discuss-gnuradio] Negative values sent to usrp.sink_c ?

[Lee Patton]

I generated a data file in which each complex sample is stored as a
32-bit value, with real and imaginary values ranging from 32000 to
-32000.  

If I connect a file source directly to a file sink, then I "receive" the
transmit data just fine.  However, if I put a USRP in between them, then
it appears that the negative values in my data are being converted to
positive before being transmitted.

I've attached a plot of my transmit data (transmit.jpg), and my received
data (received.jpg).  As you can see, the fourth pulse shows up as
positive instead of negative.  Does anyone have any ideas why?  It seems
like I'm making some simple mistake or an incorrect assumption, but I
can't figure it out.  I've attached my python script, and data file for
examination.

By the way, if it of any consequence, I have terminators on the RFX-2400
Tx/Rx and RX2 ports, and am receiving the bleed-through.

Thanks,
 Lee

received.jpg
Description: JPEG image

transmit.jpg
Description: JPEG image

test_bark5.dat
Description: MPEG movie

qa_rad.py
Description: Text Data