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Re: [Discuss-gnuradio] Need help: How to extract timestamps of data for
From: |
Josh Blum |
Subject: |
Re: [Discuss-gnuradio] Need help: How to extract timestamps of data for UHD mimo source block? |
Date: |
Thu, 07 Oct 2010 11:38:08 -0700 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.12) Gecko/20100915 Thunderbird/3.0.8 |
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 ?
http://www.ettus.com/uhd_docs/doxygen/html/structuhd_1_1rx__metadata__t.html
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?
"scalar" that is 1 metadata struct for all N aligned channels.
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" ?
Yes, it means that all N boards have the same time in their time
registers. The code here:
http://ettus-apps.sourcerepo.com/redmine/ettus/projects/uhd/repository/revisions/master/entry/host/lib/usrp/mimo_usrp.cpp#L116
I cannot say where "Time was reset" is in the code, I am surprised to
see those last 3 lines.
-Josh