Oke, Than it seems that i have a hardware problem because i see The
upper half is just repeated in the lower half, but reversed, as if
it were reflected by a mirror.
The hardware is based on the sdr1000. Iam using an AD9854 quadrature
chip.
I measured a phase difference of 90 (also after the comparators).
The signal fed to the soundcard (delta44) shows me a sinus with a
phase difference of 180. Is it also required to have 90 phase
difference for the signal fed to the soundcard?
73 Johan PA3GSB
--- In [email protected], Alberto I2PHD <[EMAIL PROTECTED]> wrote:
>
> 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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