Hi Lakshay, this might be a bit USRP-/Ettus-hardware-centric; maybe [email protected] is a better platform (in CC:)
Ringing like that might be due to a measurement device / transmitter impedance mismatch (imagine part of the wave energy travelling back and forth on the transmission line); what sink impedance is your measurement device? Best regards, Marcus On 29.08.2016 21:31, Lakshay Narula wrote: > Hi Lou, > > Thanks for your response. I am generating the baseband pulse just as > you are. Also, all pulses have the same transient behavior, not just > the first one. > > If it matters, I am using the CBX daughterboard and using a center > frequency of 2 GHz. Unfortunately I do not have an oscilloscope that > can display the frequencies that CBX transmits. So I run the signal > into this NI equipment that downconverts the pulse to baseband and > then records it. I use the same external clock to run both these > equipments. > > I realize that this set up makes it harder to debug the issue because > I have another equipment involved. But I do not have another option as > of now. > > Thanks, > Lakshay. > > On Mon, Aug 29, 2016 at 12:49 PM, madengr <[email protected] > <mailto:[email protected]>> wrote: > > How are you generating the bursts at baseband? I fill a vector > source with > (1+1j)*(numpy.ones() + numpy.zeros()) at the appropriate length > for the > sample rate, then let that repeat. I'm getting nice, clean rising > edges on > my pulses (run into an oscilloscope). Maybe the first pulse is > distorted, > but once the filters have been filled up, everything should be clean. > Lou > > > > Lakshay Narula wrote > > Hello all, > > > > I have been trying to perform ranging between nodes using > time-of-arrival > > of signals. To this end, I am trying to transmit an accurately > timed pulse > > using the USRP. My initial experiment simply sends out a 100 ms > burst > > every > > 1 sec. I am then recording this signal using NI PXIe-5663 front > end for > > analysis. Everything is working out fine, except that I am > seeing some > > wild > > transients at the beginning of the burst for several nanoseconds. > > > > I am attaching some plots that show this behavior at > > http://imgur.com/a/C0Ynq. The falling edges of the burst are > very sharp. I > > would like to get something like that on the rising edge too. > > > > In another post on the list ( > > > https://lists.gnu.org/archive/html/discuss-gnuradio/2012-06/msg00312.html > > <https://lists.gnu.org/archive/html/discuss-gnuradio/2012-06/msg00312.html>), > > Josh said that "*If you are seeing transients at the beginning > of a burst, > > thats probably the half band filters. They are implemented in block ram > > and > > don't clear **between bursts.*" > > > > Is this the reason I am seeing these transients? Is there > anything I could > > do to correct this? > > > > Thanks, > > Lakshay. > > > > _______________________________________________ > > Discuss-gnuradio mailing list > > > Discuss-gnuradio@ > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio> > > > > > > -- > View this message in context: > > http://gnuradio.4.n7.nabble.com/Transients-at-burst-rising-edge-tp61350p61351.html > > <http://gnuradio.4.n7.nabble.com/Transients-at-burst-rising-edge-tp61350p61351.html> > Sent from the GnuRadio mailing list archive at Nabble.com. > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] <mailto:[email protected]> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio> > > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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