Mixing two signals for Radar application

GNU Radio
1

Hi list,
I am in the process of building an FMCW radar. For this
to work, I have to mix two signals. I tried to do it with the
“multiply” block but no luck. I tried then to see how exactly this
block works. It seems that it does not behave As it should be. Referring
to
theory, I should see the sum and the difference of the two signals.
Looking at
the FFT plot, I can’t say that works.

What am I doing wrong? Am I missing something?

2

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Hi Dimitris,

in theory, mixing should be exactly what you’re doing - the
multiplication of a signal with another one.

Without you posting what your flow graph looks like or what the signal
you get out of it actually is, helping you might be a bit hard…
Please supply as much information as necessary to understand what
might be going wrong :wink:

Greetings,
Marcus

On 26.03.2014 15:18, Dimitris Siafarikas wrote:

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3

On 03/26/2014 03:18 PM, Dimitris Siafarikas wrote:

Hi list,

I am in the process of building an FMCW radar. For this to work, I have
to mix two signals. I tried to do it with the “multiply” block but no
luck. I tried then to see how exactly this block works. It seems that it
does not behave As it should be. Referring to theory, I should see the
sum and the difference of the two signals. Looking at the FFT plot, I
can’t say that works.

That’s true for real mixing. I assume you’re doing complex multiplying.

M