Hi Jonas, Thank you! I know that I send the signal plus carrer signal. I wanted only to explain in a simple way my problem. Best Regards,
Simona Il giorno gio 18 lug 2019 alle ore 12:11 Jonas Manthey < jonas.mant...@u-blox.com> ha scritto: > Hi, > > > > You don’t send a sine with frequency 0, you send a carrier that is > modulated by a sine with a frequency of 0. A sine with a frequency of 0 is > 0: sin(2 pi f) = sin(2 pi 0) = sin(0) = 0. > > > > So your carrier is modulated with a zero, which I **think** ends up in no > carrier at all, not sure right now how zero-IF architectures behave in that > case. I highly recommend reading some communications or RF > book/website/guide or talk with your advisor. > > > > UHD-USRP clips anything above 1 if left in the default setting (float I > guess) and there will be a lot of garbage in the sent spectrum. > > > > Cheers, > > Jonas > > > > *From:* Discuss-gnuradio [mailto:discuss-gnuradio-bounces+jonas.manthey= > u-blox....@gnu.org] *On Behalf Of *Simona Sibio > *Sent:* Donnerstag, 18. Juli 2019 13:01 > *To:* Kyeong Su Shin <kss...@postech.ac.kr> > *Cc:* discuss-gnuradio@gnu.org > *Subject:* Re: [Discuss-gnuradio] USRP GNU radio receiver > > > > Hi Kyeong, > > > > I attached the screenshots about time-domain and frequency domain. > > I sent a sine with frequency=0 and amplitude=0,25. > > The output is always zero in the receiver. > > The situation changes only if I send a sine with a frequency non-zero. > > Thank you for your time. > > Best Regards, > > > > Simona > > > > Il giorno mer 17 lug 2019 alle ore 17:41 Kyeong Su Shin < > kss...@postech.ac.kr> ha scritto: > > To whom it may concern: > > > > I think there has been some miscommunications or misunderstandings here: > the 'Offset' argument for the 'Signal Source' block is for the 'amplitude > offset' of the signal, while what Marcus probably meant in his previous > e-mail is the 'frequency offset' (you can use USRP's low-freq digital IF > capabilities for that). Also, I do not know how UHD sink behaves when you > do not input normalized values, but I am pretty sure that you should not > input such large values to UHD sink. > > > > If readings in the frequency-domain are non-zero (or, in real-world > devices, extremely low values), readings in the time-domains are also > non-zero. So, "the output became unstable in frequency and in time is > always zero" doesn't make sense. Your time-domain plot is probably zoomed > out too much. > > > > Finally, as Marcus mentioned, throttle blocks _must_ be removed. > > > > Regards, > > Kyeong Su Shin > > > ------------------------------ > > *보낸* *사람**:* Simona Sibio <ssib...@gmail.com> 대신 Discuss-gnuradio > <discuss-gnuradio-bounces+ksshin=postech.ac...@gnu.org> > *보낸* *날짜**:* 2019년 7월 17일 수요일 오후 11:35:00 > *받는* *사람**:* Müller, Marcus (CEL) > *참조**:* discuss-gnuradio@gnu.org > *제목**:* Re: [Discuss-gnuradio] USRP GNU radio receiver > > > > Thank you very much! > > I sent the screenshot because in the oscilloscope there is not the offset. > > Instead, I would like to detect that. > > Thank you in advance. > > > > Simona > > > > Il giorno mer 17 lug 2019 alle ore 15:22 Müller, Marcus (CEL) < > muel...@kit.edu> ha scritto: > > 1. Never use a throttle with a hardware block. GRC's log will actually > shout at you that you shouldn't be doing that! > 2. I must admit this is about as good as I'd expect. I of course can't > infer temporal behaviour from screenshots. > > Best regards, > Marcus > > On Wed, 2019-07-17 at 14:18 +0100, Simona Sibio wrote: > > Hi Marcus, > > > > I tried to change the offset in the transmitter but the output in the > receiver is the same, also if I send a sine signal with 10 Hz and 0,1 > amplitude: the output became unstable in frequency and in time is always > zero (see attached, 130K). > > The flow graph is attached. > > Do you have any suggestions? > > Thank you in advance. > > > > Simona > > > > Il giorno mar 16 lug 2019 alle ore 18:59 Müller, Marcus (CEL) < > muel...@kit.edu> ha scritto: > > > That phase is not any more or less random than that of your local > > > oscillator, so there might be some misunderstanding here. > > > On Tue, 2019-07-16 at 18:52 +0100, Simona Sibio wrote: > > > > Thank you very much! > > > > But, with the offset tuning I cannot edit the phase. > > > > Maybe, I have to change method. > > > > Best Regards, > > > > > > > > Simona > > > > > > > > Il giorno mar 16 lug 2019 alle ore 18:25 Müller, Marcus (CEL) < > muel...@kit.edu> ha scritto: > > > > > Well, there's leakage / DC blocking filters in most mixers, so > yes. > > > > > > > > > > But the solution is simple (and hardware-supported transparently on > > > > > USRPs): Just tune at an offset, and mix down to 0 Hz (==constant!) > in > > > > > digital. Your USRP can do that for you, google for "USRP offset > > > > > tuning". > > > > > > > > > > Best regards, > > > > > Marcus > > > > > > > > > > On Tue, 2019-07-16 at 18:15 +0100, Simona Sibio wrote: > > > > > > Thank you very much!! > > > > > > Then, I cannot measure a constant because, in the RX chain, > maybe, some filter deletes the information, doesn't it? > > > > > > Thank you for your time and tour tips! > > > > > > > > > > > > Best Regards, > > > > > > > > > > > > Simona > > > > > > > > > > > > Il giorno mar 16 lug 2019 alle ore 18:01 Müller, Marcus (CEL) < > muel...@kit.edu> ha scritto: > > > > > > > Look up what a quadrature modulator does. It's just a > multiplication > > > > > > > with e^{j2\pi f_{carrier}t}, in the end. > > > > > > > > > > > > > > Your constant signal s(t) = c const. would hence be > transmitted as > > > > > > > > > > > > > > c·e^{j2\pi f_{carrier}t} > > > > > > > > > > > > > > whereas a complex sinusoid of frequency f and amplitude a, > > > > > > > s(t) = a·e^{j2\pi f t) would be transmitted as > > > > > > > > > > > > > > a·e^{j2\pi f t)·e^{j2\pi f_{carrier}t} = a·e^{j2\pi > (f+f_{carrier})t} > > > > > > > > > > > > > > so, identical to the constant signal, just at a different > frequency. > > > > > > > > > > > > > > > > > > > > > Best regards, > > > > > > > Marcus > > > > > > > > > > > > > > On Tue, 2019-07-16 at 17:53 +0100, Simona Sibio wrote: > > > > > > > > Hi Marcus, > > > > > > > > > > > > > > > > Thank you for tip! > > > > > > > > I know that calibration is not so easy but I hope that. > > > > > > > > Could you help me to understand what happened with a > constant complex baseband signal? > > > > > > > > I am beginner in this field. > > > > > > > > Thank you for your time. > > > > > > > > > > > > > > > > Best Regards, > > > > > > > > > > > > > > > > Simona > > > > > > > > > > > > > > > > Il giorno mar 16 lug 2019 alle ore 17:39 Müller, Marcus > (CEL) <muel...@kit.edu> ha scritto: > > > > > > > > > Watch out! What do you get at the *output* of your SDR > device when you > > > > > > > > > transmit a constant complex baseband signal, mixed to a > carrier > > > > > > > > > frequency? How does that differ from transmitting a > complex baseband > > > > > > > > > sinusoid mixed to a carrier frequency? > > > > > > > > > > > > > > > > > > On Tue, 2019-07-16 at 18:32 +0200, sumit kumar wrote: > > > > > > > > > > Ok, so for a constant source, in the time domain you > will see a flat signal only! Try connecting a spectrum analyzer and you > shud see a peak at DC becz Fourier transform of constant signal is impulse. > > > > > > > > > > And yes, as Marcus said, increase the sampling rate! > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > On Tue, 16 Jul 2019 at 18:06, Simona Sibio < > ssib...@gmail.com> wrote: > > > > > > > > > > > Thank you for the assistance. > > > > > > > > > > > > > > > > > > > > > > I put the module "constant source" in my flow grap. > > > > > > > > > > > With this module, I can choose witch amplitude I want > to send. > > > > > > > > > > > I attached the flow graph. > > > > > > > > > > > And, I would want to read these values in the receiver. > > > > > > > > > > > > > > > > > > > > > > Simona > > > > > > > > > > > > > > > > > > > > > > Il giorno mar 16 lug 2019 alle ore 16:58 sumit kumar < > sumits...@gmail.com> ha scritto: > > > > > > > > > > > > Hi Simona, what is the "constant signal" here ? > > > > > > > > > > > > > > > > > > > > > > > > On Tue, 16 Jul 2019 at 17:54, Simona Sibio < > ssib...@gmail.com> wrote: > > > > > > > > > > > > > Hi all, > > > > > > > > > > > > > > > > > > > > > > > > > > I want to use GNU radio to measure the amplitude > and the phase of a signal. > > > > > > > > > > > > > I send a constant signal with the transmitter USRP > but in the receiver there is a flat signal with amplitude 0 and offset 0. > > > > > > > > > > > > > I tried to send a sine signal and the receveir > works fine. > > > > > > > > > > > > > How can I do to send only a constant and measure > the amplitude? > > > > > > > > > > > > > > > > > > > > > > > > > > Thank you for your time. > > > > > > > > > > > > > > > > > > > > > > > > > > Simona > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > > > > > > Discuss-gnuradio mailing list > > > > > > > > > > > > > Discuss-gnuradio@gnu.org > > > > > > > > > > > > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > Sumit Kumar > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > > > Discuss-gnuradio mailing list > > > > > > > > > > Discuss-gnuradio@gnu.org > > > > > > > > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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