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From: | Marcus Müller |
Subject: | Re: [Discuss-gnuradio] Constant carrier digital transmission |
Date: | Mon, 15 Aug 2016 13:40:03 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 |
Hi Frank, really, with the advances of the drivers and hardware capability and the changes in GNU Radio architecture, your problem isn't that comparable to the problem in 2009; again, please don't rely on Nabble posts; Nabble is just a mirror of the GNU mailing list archives (and adds some kind of forum infrastructure), and it has been down lately for quite some time. I don't trust it, personally, and usually urge people to directly sign up to the mailing list and use the official archives; so here's the link to the official mailing list archive's thread: http://lists.gnu.org/archive/html/discuss-gnuradio/2009-03/msg00552.html Anyway, let us really discard the idea of describing your problem
in terms of a problem from 2009; that just makes things more
complicated, because then I'd have to explain what happened to GNU
Radio in the last seven years, and why Ettus N210 & B210
driven via gr-uhd isn't like a USRP1 driven via libusrp. What
you're really asking is analogous to "my 2012 Ferrari won't start;
I found this 1920 Ford Model T hand crank start discussion, but I
can't find the hand crank in my Ferrari's trunk". Things simply
don't work like that anymore. So, this has really become much easier: The USRP sink reads
stream tags, which can contain a start-of-burst, and a
end-of-burst info; the N210 and B210 USRPs (unlike what was
available in 2009) keep an internal device time, so that they can
even be used to transmit samples at a specified time, without
having to continuously send before that time. It's important to understand the concept of stream tags to work
with this (that concept wasn't around in 2009 in the shape that
it's built into GNU Radio since roughly 2011), so I'm referring
you to the official GNU Radio tutorials [1]. Chapter 5 should explain Tags and Message Passing, but the tutorial chapters built atop of the previous ones, so I'd recommend starting with the first and working to the fifth; you will be rewarded with being able to fully understand Chapter 6, which is about interfacing what you've built in chapters 1-4 with real USRP hardware, and with an instant understanding of [2], the documentation of how to send "bursty" samples to the USRP via stream tags! For a demo of how to use stream tags to tune at a specific time and annotate, see [3]; if you run that as ./freq_hopping.py -r 2.5e5 -N 10000 -t 500 -f 2.4e9 -c 100 -d
2.5e6 -v with your B210 attached, you should see its TX LED blink exactly
twice per second. Best regards, Marcus [2] http://gnuradio.org/doc/doxygen/classgr_1_1uhd_1_1usrp__sink.html [3] https://github.com/gnuradio/gnuradio/blob/v3.7.10.1/gr-uhd/examples/python/freq_hopping.py On 15.08.2016 13:07, Inspire Me wrote:
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