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From: | Nowlan, Sean |
Subject: | Re: [Discuss-gnuradio] How to implement a TDMA system |
Date: | Mon, 23 Apr 2012 15:14:23 +0000 |
In my case, I modified the stream tag example under gr-uhd/examples to make a "burst_tagger" block. I kept the work function essentially the same since it already handles bursting
for a specified duration and repeats this behavior over a specified cycle time. This method of bursting works nicely. The stream tags you need to care about are called "tx_time", "tx_sob" (start-of-burst), and "tx_eob" (end-of-burst), respectively. These tags
are affixed in the work function of the stream tags example mentioned above. The gr_uhd_usrp_sink block already has the logic to translate these tags into UHD commands, so you shouldn't need to worry about that.
I don't think you can do this from Python yet, but I could be wrong about that. One last thing I'll mention is that there is a "set_start_time" function in gr_uhd_usrp_sink that can set an absolute start time for transmission (essentially the USRP will block the stream from the flowgraph until the USRP's internal time register reaches the time you set). Sean From: discuss-gnuradio-bounces+address@hidden [discuss-gnuradio-bounces+address@hidden on behalf of Pan, Luyuan address@hidden
Sent: Monday, April 23, 2012 11:04 AM To: Tom Rondeau Cc: address@hidden Subject: Re: [Discuss-gnuradio] How to implement a TDMA system Hello,
Thank you so much for your reply. And I also read your presentation and audio about "Stream tag" on the website of GnuRadio Conference 2011, I want to know a few questions about it: 1. I think you defined some auxiliary control information to make the stream start or stop on desired time, but above the UHD/gr-uhd and has nothing to do with UHD, did I misunderstand it? 2. May I use the "stream tag" to achieve my goal of TDMA system?(consider the precision and efficiency) 3. If so, and as the time-stamp cannot get through the gr-uhd, whether is it more convenient for me to use the "stream tag"? Or maybe I can code in some higher level like python? Any comment/suggestion is greatly appreciated, thank you~ --
Best regards, Luyuan Pan
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