On 03/09/2018 03:23 AM, Derek Kozel via USRP-users wrote:
Hello,
Yes, that is the purpose of the set_time_next_pps function. When
combined with common 10 MHz and 1 PPS references this allows for
stable time synchronization of 1 sample clock cycle, 5 ns at 200 MS/s.
I recommend reading through the examples which show using all these
commands and others related to streaming multiple channels.
https://github.com/EttusResearch/uhd/tree/maint/host/examples
The manual also covers these topics.
http://files.ettus.com/manual/page_sync.html
Derek
There's also, of course:
https://kb.ettus.com/Synchronization_and_MIMO_Capability_with_USRP_Devices
On Thu, Mar 8, 2018 at 11:02 PM, Zhongyuan Zhao <zhz...@cse.unl.edu
<mailto:zhz...@cse.unl.edu>> wrote:
Hi Derek,
If USRPs A & B clocked by an Octoclock, are connected to the same
host, I want calibrate the counter values from USRPs A and B. How
can I do it? Is this function supported by UHD? If not, could I
update the counter values in the FPGA Radio blocks? or I can only
keep an calibration table of counter value offsets on my host?
Thanks!
Zhongyuan Zhao
PhD Candidate,
Department of Computer Science & Engineering,
University of Nebraska-Lincoln
Office Hour: WF 9:30-10:00am, Avery Hall 12,
Suite 117, Schorr Center,
Lincoln, Nebraska 68588-0115
On Thu, Mar 8, 2018 at 4:42 PM, Derek Kozel <derek.ko...@ettus.com
<mailto:derek.ko...@ettus.com>> wrote:
Hello,
The same commands are available in the GNU Radio environment
and I believe are exposed in the pre-release Python API branch.
The FPGA radio blocks contain a timekeeper which is a counter
which increments at the same rate as the master_clock_rate
which is the effective ADC/DAC sample rate. This allows for
commands to be executed with very fine temporal precision.
Regards,
Derek
On Thu, Mar 8, 2018 at 10:12 PM, Zhongyuan Zhao
<zhz...@cse.unl.edu <mailto:zhz...@cse.unl.edu>> wrote:
Hi Derek,
I have two questions about the rx timed samples example,
1. is there python version for timed command?
2. Is the time stamp from the clock on USRP or on the host?
Thanks
Zhongyuan Zhao
PhD Candidate,
Department of Computer Science & Engineering,
University of Nebraska-Lincoln
Office Hour: WF 9:30-10:00am, Avery Hall 12,
Suite 117, Schorr Center,
Lincoln, Nebraska 68588-0115
On Thu, Mar 8, 2018 at 3:27 PM, Derek Kozel via USRP-users
<usrp-users@lists.ettus.com
<mailto:usrp-users@lists.ettus.com>> wrote:
The stream command object has a field for a time spec
of when to start streaming and a boolean flag for
whether to make use of that time spec.
http://files.ettus.com/manual/structuhd_1_1stream__cmd__t.html
<http://files.ettus.com/manual/structuhd_1_1stream__cmd__t.html>
Here we can see it used in an rx example.
https://github.com/EttusResearch/uhd/blob/maint/host/examples/rx_timed_samples.cpp#L92-L93
<https://github.com/EttusResearch/uhd/blob/maint/host/examples/rx_timed_samples.cpp#L92-L93>
Usually it is most practical to make a call to
get_time_now() and then add an offset from that time
which is returned. The minimum offset would be the
roundtrip command time, usually a few milliseconds.
Regards,
Derek
On Thu, Mar 8, 2018 at 9:03 PM, Andrew Thommesen
<andrewjoh...@outlook.com
<mailto:andrewjoh...@outlook.com>> wrote:
No, how do you do that?
Sent from Outlook <http://aka.ms/weboutlook>
------------------------------------------------------------------------
*From:* Derek Kozel <derek.ko...@ettus.com
<mailto:derek.ko...@ettus.com>>
*Sent:* 08 March 2018 20:58:38
*To:* Andrew Thommesen
*Cc:* usrp-users
*Subject:* Re: [USRP-users] TwinRx Channel Alignment
Hello Andrew,
Are you starting the streaming with timed commands?
Regards,
Derek
On Mar 8, 2018 7:32 PM, "Andrew Thommesen via
USRP-users" <usrp-users@lists.ettus.com
<mailto:usrp-users@lists.ettus.com>> wrote:
Hi all,
I have an x310 with a twinRx and would like to
process coherent, time aligned data within the
FPGA. However, the data is not currently time
aligned and there is an offset of ~400 samples
between the two channels.
The RFNoC radio block is configured to receive
data on both channels, with the LO of channel
1 set to companion. The output of the radio
block then passes through the RFNoC DDC block
that decimates from 100MSPS to 50MSPS. The
decimated data then passes to a custom RFNoC
block that strips out the timestamps (for
loopback). It is within this custom block that
the the offset is detected at the output of
the AXI wrapper before any processing has
taken place.
Any ideas?
Andy
Sent from Outlook <http://aka.ms/weboutlook>
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