Multiband combiner block is atten the signal for no reason.

Greeting.

I am trying to simulate the interference of 2 signal by combine them using "Multiband Combniner Block" in simulink. as below diagram

First signal is very narrow band signal (carrier ~1 kHz) (Primary signal)

Second signal is wide band sigal (Carrier ~250 kHz) (Interfere signal)

Anyway, the spectrum for both Primary signal and Interfere sigal looks ok (as screenshot below)

but when I look at the spectrum after "Multiband Combiner" block, seems the interfere signal got attenuation around 60-70 dB in the spectrum analyzer.

And from the block configuration, I don't see any related on atten the signal.

What is the possible cause that my intefere signal is being attenuate and how can I fix this?

Best Regads,

Fumihiko Sato

Answer 1

[UDAYA PEDDIRAJU]

Hi Fumihiko,

The algorithm behind multiband combiner block basically shift the signal as per the offset frequency then all the shifted components are added to make the final signal. You should go through the following link to understand the functionality of the block: https://www.mathworks.com/help/comm/ref/multibandcombiner.html#mw_378beb19-33b6-45a1-9629-53150fba273c:~:text=When%20the%20output,number%20of%20samples.

Let me know if you have any trouble?