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
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
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~
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
Best regards,
Luyuan Pan
On Sun, Apr 22, 2012 at 3:16 AM, Pan, Luyuan <address@hidden> wrote:Hi everyone, I want to implement a TDD system with three USRP2 and an IBM server with three Ethernet cards. The scenario is one relay and two nodes exchange data through the relay, I want them to transmit data in their fixed time slot, it does not need to be too precise, about 100 milliseconds per slot is OK. The question is: 1. Can I achieve my goal with the current equipment?I'm pretty sure, yes. The 100 ms should be pretty easily achievable.2. I want to use the time-stamp in UHD to precise control the time to send and recv, but without external clock, does the UHD have to use the external clock to get the time?No, you do not need an external clock for this. All time in the UHD land is relative, so you should be able to say "send packet 100 ms from now" without caring what absolute time 'now' is. TomThank you in advance! -- Best regards, Pan, LuyuanHi everyone,
I want to implement a TDD system with three USRP2 and an IBM server with three Ethernet cards. The scenario is one relay and two nodes exchange data through the relay, I want them to transmit data in their fixed time slot, it does not need to be too precise, about 100 milliseconds per slot is OK. The question is:
1. Can I achieve my goal with the current equipment?
2. I want to use the time-stamp in UHD to precise control the time to send and recv, but without external clock, does the UHD have to use the external clock to get the time?
Thank you in advance!
