[USRP-users] GPSO Vita timestamp

Josh Blum josh at ettus.com
Fri Feb 1 15:55:22 EST 2013



On 02/01/2013 01:36 PM, A Bose wrote:
>  Hello,
> 
> I am using a N200 and UHD in windows, and I am trying to set the VITA frame
> timestamp to the GPS time. The md.time_spec.get_full_secs() seems to go
> positive and negative and is just random and is the same at the
> super_recv_packet_handler.hpp after the packet receive.
> 
> Here is my code:
> 
> 	usrp->set_clock_source("external");
> 	//set_time_source allows the FPGAs internal tick counter to be
> synchronized by a PPS pulse coming into the external SMA
> 	usrp->set_time_source("external");
> ...
> //setup the VITA frame time to gps_time
> uhd::sensor_value_t gps_time = usrp->get_mboard_sensor("gps_time");
> uhd::time_spec_t gpsTime =  uhd::time_spec_t(1.0)
> +uhd::time_spec_t((double)gps_time.to_int());
> 
> //set the gps time
> usrp->set_time_next_pps(gpsTime);
> boost::this_thread::sleep(boost::posix_time::seconds(1.5)); //wait for pps
> sync pulse
> uhd::time_spec_t last_pps_time2 = usrp->get_time_last_pps();
> 
> boost::posix_time::ptime tpps(date(1970,1,1),
> boost::posix_time::seconds(last_pps_time2.get_full_secs()));
> std::string testLastPPS = to_simple_string(tpps); //THIS IS GOOD
> 
>     //setup streaming
>     uhd::stream_cmd_t stream_cmd((num_requested_samples == 0)?
>         uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS:
>         uhd::stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE
>     );
>     stream_cmd.num_samps = num_requested_samples;
>     stream_cmd.stream_now = true;
>     stream_cmd.time_spec = uhd::time_spec_t();
> 
>     usrp->issue_stream_cmd(stream_cmd);
> 
>     while(not stop_signal_called and (num_requested_samples !=
> num_total_samps or num_requested_samples == 0)){
>         size_t num_rx_samps = rx_stream->recv(&buff.front(), buff.size(),
> md, 3.0);
>         ...
>       //error checking
>         ...
>         num_total_samps += num_rx_samps;
>         outfile.write((const char*)&buff.front(),
> num_rx_samps*sizeof(samp_type));
>     }
> 
>  boost::posix_time::ptime t0(date(1970,1,1),
> boost::posix_time::seconds(md.time_spec.get_full_secs()));
>  std::string test0 = to_simple_string(t0); //THIS IS BAD

OK I see what the test is doing.
So, can you tell me, what is the value of:

md.has_time_spec
md.error_code
md.time_spec.get_full_secs()
md.time_spec.get_frac_secs()

-josh

>   
> //get pps time again to check 
> uhd::time_spec_t last_pps_time3 = usrp->get_time_last_pps();
> boost::posix_time::ptime tpps3(date(1970,1,1),
> boost::posix_time::seconds(last_pps_time3.get_full_secs()));
> std::string testLastPPS3 = to_simple_string(tpps); //THIS IS GOOD
> 
> 
> The Vita Frame timestamp just doesn't seem to be set to the internal time.
> 
> Any ideas?
> 
> Thanks,
> A Bose
> 
> -----Original Message-----
> From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of
> Josh Blum
> Sent: Friday, February 01, 2013 11:24 AM
> To: usrp-users at lists.ettus.com
> Subject: Re: [USRP-users] GPSO 1PSS
> 
> 
> 
> On 02/01/2013 10:09 AM, A Bose wrote:
>> I am having the exact same problem and  I found this discrepancy:
>>
>>  
>>
>> The latest
>>
>> http://code.ettus.com/redmine/ettus/projects/uhd/repository/revisions/
>> fac15d 
>> b5d77c5196badb4a06f2f5fec34eb57337/entry/host/lib/transport/super_recv
>> _packe t_handler.hpp has fixed the meta time to include seconds:
>>
>> info.time = time_spec_t(time_t(info.ifpi.tsi), size_t(info.ifpi.tsf), 
>> _tick_rate); //assumes has_tsi and has_tsf are true
>>
>>  
>>
>> but the 003.005.001 release has the old code bug with no seconds:
>>
>> info.time = time_spec_t::from_ticks(info.ifpi.tsf, _tick_rate); 
>> //assumes has_tsf is true
>>
> 
> The time is always parsed from the packet, even if the fields may not have
> been populated. The time is qualified with the has_time_spec which is also
> parsed from the packet. So time is only valid if the boolean field says
> true.
> 
>>  
>>
>> I am running with an old FPGA rev and this fix doesn't work for me, so 
>> I am assuming there is/was something wrong on the FPGA side as well? 
>> If so does anyone know what exactly was fixed (what rev)?
>>
> 
> Sorry I am unsure, but what exactly is the issue?
> 
> -josh
> 
>>  
>>
>> From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf 
>> Of Damien Serant
>> Sent: Thursday, January 31, 2013 8:31 PM
>> To: Nick Foster
>> Cc: USRP List
>> Subject: Re: [USRP-users] GPSO 1PSS
>>
>>  
>>
>> Thanks Nick for your kick answer.
>>
>>  
>>
>> "We just recently fixed a bug relating to this." 
>>
>> I know. I am using UHD 003.005.001 (from installer) which contains the 
>> patch according to the repository. May be the installer does not have the
> patch ?
>> I will try tomorrow to build from source.
>>
>>  
>>
>> "Can you cut and paste the relevant section of code?"
>>
>> From memory (i don't have access to my code right now) :
>>
>>  
>>
>> For the stream command config:
>>
>> uhd::stream_cmd_t
>> stream_cmd(uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS);
>>
>> stream_cmd.stream_now = false;
>>
>> stream_cmd.time_spec = get_time_last_pps()+1;
>>
>> usrp->issue_stream_cmd(stream_cmd);
>>
>> cout<<fixed<<setprecision(9)<<get_time_last_pps().get_real_secs()<<end
>> l;
>> //Not full sec
>>
>>  
>>
>> For the receiving part:
>>
>> nbSamp = 0;
>>
>> timeout = 3;
>>
>> while(nbSamp<nbSampTot){
>>
>>   num_rx_samps = rx_stream->recv(&buff.front(), buff.size(), md, 
>> timeout);
>> //buff.size() about 100000
>>
>>   if(nbSamp == 0){
>>
>>     cout<<fixed<<setprecision(9)<<md.time_spec.get_real_secs()<<endl; 
>> //Not full sec
>>
>>   }
>>
>>   timeout = 0.1;
>>
>>   nbSamp+=num_rx_samps;
>>
>>   ...
>>
>> }
>>
>>  
>>
>> May be i don't use the right method to extract the time from the time spec
> ?
>>
>> Since i wrote this from memory it is possible that there is an error 
>> in my actual code and not here...
>>
>>  
>>
>>  
>>
>> Damien
>>
>>  
>>
>> 2013/2/1 Nick Foster <nick at ettus.com>
>>
>> On 01/31/2013 04:00 PM, Damien Serant wrote:
>>
>> Hi list,
>>
>>  
>>
>> Two small issues about 1PPS signal with the GPSDO:
>>
>>   1) When i run the query_gpsdo_sensors util i obtain : "GPS locked", 
>> "10 MHz" locked but always "GPS and UHD Device time are NOT aligned" 
>> (I triple checked the 1PPS connection)
>>
>> We just recently fixed a bug relating to this. The PPS functionality 
>> is fine; the query_gpsdo_sensors program wasn't waiting long enough to 
>> be sure the PPS had been latched in. It's checked into master, but I 
>> don't think a release has been cut since then.
>>
>>
>>
>>
>>
>>
>>   2) I my program the time get from the "get_time_last_pps()" function 
>> is surprisingly never a full second (about 500 ns before or after a 
>> full second). In the same way, when i set the time spec of a receiver 
>> stream with get_time_last_pps() + 1, i never get a full second in the 
>> time spec field of the metadata of the first received packet .
>>
>> This is a normal behavior and if yes why ?
>>
>> Can you cut and paste the relevant section of code?
>>
>> --n
>>
>>
>>
>>
>>  
>>
>> Configuration; win XP, USRP N200 r4 with SBX daughterboard, UHD 351.
>>
>>  
>>
>> Thanks,
>>
>>
>> Damien
>>
>>  
>>
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>>
>>  
>>
>>  
>>
>>
>>
>>
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> 
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