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Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver)
From: |
Douglas Geiger |
Subject: |
Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver) |
Date: |
Fri, 20 Feb 2009 14:03:08 -0600 |
User-agent: |
Thunderbird 2.0.0.19 (Windows/20081209) |
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Douglas Geiger wrote:
> Matt Ettus wrote:
>> Sync_to_pps is all about timestamps and the pps input, so it is not
>> related to whether or not the clock is locked.
>
> Right, got it.
>
>> Just to clarify the clocking architecture on the USRP2, there are
>> basically 3 modes:
>
>> - Free running
>> - Locked to the external SMA reference input
>> - Locked to the clock which comes over the MIMO cable from another USRP2
>
>> You need to make sure you are in the 2nd one, aka "we lock to SMA". It
>> sounds like whatever code you are running is setting the mode to "we
>> lock to MIMO connector" mode.
>
>> Matt
>
> You're correct - it looks like as soon as I call config_mimo, it looses
> the lock to SMA. I'm a bit confused as to why that is - I'm calling it
> with MC_WE_LOCK_TO_SMA which is defined in usrp2_mimo_config.h - it
> basically comes out as 0x0001 (i.e. _MC_WE_LOCK | 0, where _MC_WE_LOCK
> is 0x0001).
>
It looks like usrp2_impl.cc never passes on the argument when you call
config_mimo - I've attached a quick patch that I believe does the job
correctly.
When I run my host code now the clocks on my USRP2's remain
synchronized to my external source.
Doug
- --
Doug Geiger
Research Assistant
Communications and Signal Processing Lab
Oklahoma State University
http://cspl.okstate.edu
address@hidden
address@hidden
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Index: usrp2_impl.cc
===================================================================
--- usrp2_impl.cc (revision 10441)
+++ usrp2_impl.cc (working copy)
@@ -995,6 +998,7 @@
cmd.op.opcode = OP_CONFIG_MIMO;
cmd.op.len = sizeof(cmd.op);
cmd.op.rid = d_next_rid++;
+ cmd.op.flags = flags;
cmd.eop.opcode = OP_EOP;
cmd.eop.len = sizeof(cmd.eop);
- Re: [Discuss-gnuradio] Re: Re: Re: USRP2 and external clock (from GPS receiver), (continued)
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Douglas Geiger, 2009/02/19
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Matt Ettus, 2009/02/19
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Douglas Geiger, 2009/02/19
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Matt Ettus, 2009/02/19
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Douglas Geiger, 2009/02/19
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Matt Ettus, 2009/02/19
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Douglas Geiger, 2009/02/20
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Matt Ettus, 2009/02/20
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Douglas Geiger, 2009/02/20
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver),
Douglas Geiger <=
- Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver), Eric Blossom, 2009/02/20