Re: [Discuss-gnuradio] How do I capture of the time of USRP N210 samples with host computer system time?

[LD Zhang]

Thanks to Josh and Marcus for their comments. The set_time_now command
works! After I put it in, the earlier observed 0.5 sec offset between the 2
USRP became ~0.1 second. So there is still work to do. I guess my options
are:

1. Make the set_start_time command to work. My question is how I can make it
work in python. I hand edited the set_time_now command to embed in the
initialization part of the top_block.py code generated from GRC (which has
worked). Do I just hand edit the set_start_time just following that command?
Now the problem is that after set_time_now, the USRP time is sync'd to the
system time. But what is the argument I should give to set_start_time?

2. The other option is to get the metadata out for the samples collected.
>From what I read, it looks like one cannot do it in GRC, but have to edit
the cpp source code. Is there an example somewhere of how this is done?

Thanks very much,

LD

-----Original Message-----
From: LD Zhang [mailto:address@hidden 
Sent: Friday, January 04, 2013 5:38 PM
To: 'Marcus D. Leech'; 'address@hidden'
Subject: RE: [Discuss-gnuradio] How do I capture of the time of USRP N210
samples with host computer system time?

Great! Thanks. I tried to import time and it works. Now I just have to see
if this is sufficient for my sample gather timing or I still have to get the
timestamp of the first sample using metadata and such.

LD

-----Original Message-----
From: Marcus D. Leech [mailto:address@hidden
Sent: Friday, January 04, 2013 4:15 PM
To: LD Zhang; address@hidden
Subject: Re: [Discuss-gnuradio] How do I capture of the time of USRP N210
samples with host computer system time?

On 01/04/2013 07:03 PM, LD Zhang wrote:
> Hello,
>
> I tried the following command in python:
>
>> python:
>> usrp_source.set_time_now(uhd.time_spec_t(time.time())
>>
> It doesn't seem to work. Looks like the "time.time()" is wrong? Looked 
> up an earlier example:
>
> set_time_now(uhd::time_spec_t(0.0), 0)
>
> The syntax looks different. But this may be doing something different 
> from my intention which is to sync the USRP time to the host system 
> time. I am still searching for the right syntax for this command. Any 
> help is appreciated.
>
> LD
>
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>
You'll have to put an:

import time

In your python



--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org