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Re: [Discuss-gnuradio] I&Q on same or separate channels?
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] I&Q on same or separate channels? |
Date: |
Thu, 13 Dec 2007 22:19:14 -0800 |
User-agent: |
Mutt/1.5.17 (2007-11-01) |
On Thu, Dec 13, 2007 at 04:35:51PM -0500, George Nychis wrote:
> 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
I and Q are not on separate channels. They are interleaved,
I0, Q0, I1, Q1...
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, (continued)
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, George Nychis, 2007/12/13
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, Brian Padalino, 2007/12/13
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, George Nychis, 2007/12/14
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, Brian Padalino, 2007/12/16
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, George Nychis, 2007/12/16
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, Brian Padalino, 2007/12/16
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, George Nychis, 2007/12/16
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, George Nychis, 2007/12/16
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, Brian Padalino, 2007/12/16
- Re: [Discuss-gnuradio] I&Q on same or separate channels?, George Nychis, 2007/12/16
Re: [Discuss-gnuradio] I&Q on same or separate channels?,
Eric Blossom <=