Re: [Discuss-gnuradio] Need help: How to extract timestamps of data for UHD mimo source block?

Hi Josh,

Thanks so much for your reply.

I have some questions about the metadata.

1). I read the codes in the work function. The metadata is defined by:
uhd::rx_metadata_t metadata;

Does "uhd::rx_metadata_t" define the data type or give values to
metadata? And in which C++ file may I find that the "uhd::rx_metadata_t" is
created ?

2). Is metadata a scaler or vector? I use 4 USRP2 boards for MIMO receiver
system. Does metadata contain 4 groups of timestamps for each 4 USRP2 boards
or just 1 group of timestamps for the whole synchronised data?

3). When I use the UHD MIMO Source block, GNU Radio Companion shows the
following sentences:

Current recv sock buff size: 50000000 bytes
Current recv sock buff size: 50000000 bytes
Current recv sock buff size: 50000000 bytes
Current recv sock buff size: 50000000 bytes
Using: Flex 2400 MIMO B RX (0x0027)
Using: Flex 2400 MIMO B TX (0x002b)
Using: Flex 2400 MIMO B RX (0x0027)
Using: Flex 2400 MIMO B TX (0x002b)
Using: Flex 2400 MIMO B RX (0x0027)
Using: Flex 2400 MIMO B TX (0x002b)
Using: Flex 2400 MIMO B RX (0x0027)
Using: Flex 2400 MIMO B TX (0x002b)
RX samples per packet: 362
TX samples per packet: 363
Recv pirate num frames: 33967
Set time with unknown pps edge:
1) set times next pps (race condition)
2) catch seconds rollover at pps edge
3) set times next pps (synchronously)
Time was reset successfully on board 1 relative to board 0
Time was reset successfully on board 2 relative to board 0
Time was reset successfully on board 3 relative to board 0

Do they mean that 4 boards are synchronised and have the same timestamps? In
which C++ script may I find this sentence :" Time was reset successfully on
board 1 relative to board 0" ?

Many thanks in advance.

Best wishes,
Hongliang

Josh Blum-2 wrote:
>
>
>
> On 10/06/2010 04:24 AM, Hongliang Zhang wrote:
>>
>> Hi everyone,
>>
>> I set up 4 USRP2 boards for MIMO receiver system for array antennas, and
>> use
>> the PPS signal to synchronise them. I wish to collect the data from the
>> boards as well as the associated timestamps for the four boards.
>>
>> Could someone teach me how to read the time stamps from a UHD mimo source
>> block? Do I need to modify the block in C++ or Python scripts?
>>
>
> The timestamps are inside the metadata, they are discarded in the work
> function:
> http://gnuradio.org/cgit/gnuradio.git/tree/gr-uhd/lib/uhd_mimo_source.cc?h=next#n127
>
> You will need to modify the mimo source c++ and find a place to store
> the timestamps, or write a c++ app that calls into the UHD mimo_usrp
> interface directly.
>
> -Josh
>
>> Thanks so much for every help and suggestions.:clap:
>>
>> Best regards,
>> Hongliang
>
> _______________________________________________
> Discuss-gnuradio mailing list
> Discuss-gnuradio@gnu.org
> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>

--
View this message in context: http://old.nabble.com/Need-help%3A-How-to-extract-timestamps-of-data-for-UHD-mimo-source-block--tp29886484p29908883.html
Sent from the GnuRadio mailing list archive at Nabble.com.

_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio