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Re: [Discuss-gnuradio] USRP DDC usage
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] USRP DDC usage |
Date: |
Thu, 26 May 2005 19:51:27 -0700 |
User-agent: |
Mutt/1.5.6i |
On Thu, May 26, 2005 at 04:41:17PM -0700, Matt Ettus wrote:
>
> > Even if you set the frequency to 0, there is a "random" initial phase
> > that is unknown, and thus you cannot separate the two channels.
>
> The initial phase is always 0 at power up. If you never set the
> frequency to something other than 0, it will always stay that way. Its
> a simple change to make the phase go back to zero. Patches welcome...
>
> Matt
A couple of hints:
You'll need a bit in an FPGA register to control the resetting to
zero. Edit usrp/firmware/include/fpga_regs_standard.h and add
// Reset phase accumulator to zero for those with bits set.
// E.g., writing a 0x000f resets them all. Writing 0x0001 resets
// the phase accumulator associated with DDC 0.
#define FR_PHI_RESET 44
Doing a make in usrp/firmware/include will generate
fpga_regs_standard.v from fpga_regs_standard.h
Then look at these files to figure out the rest:
usrp/fpga/sdr_lib/serial_io.v
usrp/fpga/toplevel/usrp_std/usrp_std.v
Eric
- [Discuss-gnuradio] Delta 44, (continued)
- [Discuss-gnuradio] Delta 44, Bob McGwier N4HY, 2005/05/26
- Re: [Discuss-gnuradio] Delta 44, Eric Blossom, 2005/05/27
- Re: [Discuss-gnuradio] Delta 44, n4hy, 2005/05/27
- Re: [Discuss-gnuradio] Delta 44, Matt Ettus, 2005/05/27
- Re: [Discuss-gnuradio] Delta 44, n4hy, 2005/05/27
- Re: [Discuss-gnuradio] Delta 44, James Cooley, 2005/05/27
- Re: [Discuss-gnuradio] Delta 44, Eric Blossom, 2005/05/28
Re: [Discuss-gnuradio] USRP DDC usage, Krzysztof Kamieniecki, 2005/05/26
Re: [Discuss-gnuradio] USRP DDC usage, Matt Ettus, 2005/05/26