Re: [Discuss-gnuradio] UHD I/O Data Types

[Marcus D. Leech]

> You cannot represent a "pure" sinusoid with a real signal. Think e^(jw)
> vs Re{e^(jw)} Maybe someone could think of a better way to say this.
>
> All USRP devices input and output complex baseband. You need to
> represent your signal in complex baseband. I suggest experimenting by
> feeding your signal into the _complex_ fft plotter in grc and see how it
> looks spectrally, because thats how your actual spectrum will look when
> you transmit, but shifted up by fc Hz.
>
> -Josh
>
> _
One could take that real sinusoid, and translate it into the complex 
plane with a
  Hilbert transform, and there's a block for doing that.

Although, if this is a pre-recorded signal, one could simply do the 
Hilbert transform
  "offline", and have the pre-recorded signal be already transformed 
into the complex
  plane.

But if Arya is already using a signal-generator block within GRC or C++, 
they could simply
  use the already-existing complex output type.

The hardware expects signals to be represented in the complex plane, 
even when there is no negative
  frequency content of said signals.



--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org