Re: [Discuss-gnuradio] USRP GNU radio receiver

[Simona Sibio]

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) <address@hidden> 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) <address@hidden> 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 <address@hidden> 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 <address@hidden> ha scritto:
> > > > > Hi Simona, what is the "constant signal" here ?
> > > > >
> > > > > On Tue, 16 Jul 2019 at 17:54, Simona Sibio <address@hidden> 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
> > > > > > address@hidden
> > > > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > > > >
> > > > >
> > > > > --
> > > > > Sumit Kumar
> > > > >
> > > > >
> > >
> > >
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