johanmaas2001 wrote:
> Hi again,
>
> I found the problem; the connector is defect; after replacing the
> connector the system is doing the demodulation for only the I or Q
> signal.

I am not sure to understand you fully. What you mean when you say that the demodulation is done for only the I or Q
signal ? What should happen is the following. If you connect only I or only Q, you should see the spectrum mirrored
about its center. The upper half is just repeated in the lower half, but reversed, as if it were reflected by a mirror.
If both I and Q are correctly connected and they have the right balance in amplitude and phase, then the lower and upper
half are independent, and each shows correctly its range of frequencies.
>
> Only using the RF source to see the one or two peaks... iam seeing 2
> peaks.

If connecting an external signal generator you see two peaks symmetric with respect to the band center, then something
is wrong with your hardware. Either one of the two I/Q is missing, or their amplitude/phase balance is completely wrong.
>
> I did measure the amplitude of the dds signal this seems oke.
>
Do you use a quadrature DDS that produces I/Q LO ?

> Also the phase seems oke, at least on the scoop. what is the best
> approach of measuring the phase error?
>
What you mean saying that the phase looked good on the scope ? What measure did you do ?

73  Alberto  I2PHD


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