Help me to solve the problem in analog filter in SIMULINK

[roshe32]

Hi guys ,

I want to use analog filter box of SIMULINK in a system simulation. the filter is a bandpass filter from 10 to 12 GHz butterworth. but it doesn't work at this hight frequency when I set the parameters in filter setup box ...it works only in a very lower frequency (MHz)...can any body help me with this problem?

 

[venturer84]

I am a little confused? What do you mean it works at lower frequency? One possible cause could be the implementation errors in FIR/IIR approximation. As i understand, Simulink is a time domain simulation tool, so the filter block must be doing some FIR/IIR for the time domain response. now filters in time domain are designed in respect to sampling frequencies. If your sampling frequency is too high, FIR/IIR implementation might struggle to get a good time domain response.

My response above is acually based on guess work. Without looking at your setup, its actually very difficult to figure out what might be the problem.

 

[roshe32]

Re: Help me to solve the problem in analog filter in SIMULIN

Thnaks for your explenation. ...I have but no idea how to use this approximation. if I am not wrong this means approximation of finfinite impulse response (FIR) filters by infinite impulse response (IIR) filters. can you guide me how can I use this approximation? or shall I send you a sample of this filter?

 

[venturer84]

Sadly i dont have a simulink license anymore.

But i was correct with my guess...
**broken link removed**

It does indeed uses IIR implementation.

What is the main goal of your simulation? Are you simulating some sort of Analog link with a time domain/Modulated Signal?

 

[roshe32]

Re: Help me to solve the problem in analog filter in SIMULIN

Actually I am simulating a Radiometer receiver. it is a simple total power radiometer which receives temperture noise of the abject and limit the frequency noise( which is suppose to be white noise) to the frequncy of 10 to 12GHz. ja! it is a time domain signal. the output of the radiometer is a dc voltage which can be achieved after a lowpass filter and an integrator.