interpolation effect in the frequency domain of the spectrum analizer

[yefj]

Hello,When we interpolate by 2 that means that our frequency axes shrinks by 2 as i know from the simple theory.
But we i look at a system from a real DAC as shown in the spectrum analizer photos bellow.
I have an I/Q modulated signal of 5Mhz baseband going into 2300 mixer frequency and the signal is intepulated by 2
I get a very complex behavior shown bellow.
I made marker table on it the photos.
maybe the system is not exactly acts by the numbers i said..
How can i interpret this spectrum analizer photos and see the intepolation effect in it?
Thanks.

 

[FvM]

Please start with a complete description of your setup, including applied sampling rates etc. Where do you use interpolation?

Apparently, the base band signal has 30 MHz sampling rate and is modulating the carrier without appropriate filtering, resulting in a 30 MHz aliasing pattern.

 

[biff44]

you are most likely letting the spectrum analyzer automatically choose a resolution bandwidth. make it manual!

 

[yefj]

Hello FVM, i know that when we do upsampling by 2 the nyquist zones divided by 2
could you please say where are the nyquist zones in my photos?
Thanks.

--- Updated Jun 4, 2021 ---

Hello FVM,intermodulation causes the nyquist zones to expand by the intermodulation factor.
so if the spacing is by 30MHZ and we have intermodulation by 2 factor then our
sampling rate is 15Mhz?
correct?

 

[FvM]

Please start with a complete description of your setup, including applied sampling rates etc.