[Discuss-gnuradio] I&Q on same or separate channels?

[George Nychis]

Hi all,

For the in-band code, I'm noticing that it seems like the FPGA is 
packing two I's or two Q's, and not an I and a Q.  If you take a look at 
the following plot of a 10MHz sine wave, you will see what I mean.  The 
left plot is using the legacy receiver, the right side is using an 
in-band receiver:
http://www.andrew.cmu.edu/user/gnychis/sines.png

This boils down to the following code:
http://gnuradio.org/trac/browser/gnuradio/branches/features/inband-usb/usrp/fpga/inband_lib/rx_buffer_inband.v

I'm guessing that Thibaud's original assumption was that I and Q are 
packed in a single channel to be read from.  With a single data channel, 
the code will only read from channel 0.  Is this incorrect?  If so, this 
explains the behavior we're seeing.

If I and Q are on separate channels, are they synchronized?

- George