Nulling filter for removing an pulse

[pattalol]

hey!

I'm having some problems removing a pulse from my signal.

I have the output y[n]=x[n]+0.25x[n-Ne], where Ne = 2205.

System function H(z)=(z^Ne + 0.25)/z^Ne

What i want to do is to remove the pulse 0.25*delta[n-Ne].

Im very new to DSP, so what i first did was to try cascading FIR filters, but it didn't work... so im kinda lost atm.

So can anyone give me some ideas of how I can remove the peak 0.25delta[n-Ne]???

As you can see, i want to remove the last pulse

 

[FvM]

You'll remove the "echo" in the transfer function by a filter with the inverse transfer function.

The echo cancellation filter will be however an IIR filter.

 

[pattalol]

Thanks for the idea Fvm!

Will read up on IIR filters, and try again

 

[pattalol]

Calculated the inverse transfer function filter

Another question arose tho... why is this not a FIR filter???
You said it was an IIR filter, but i cant seem to understand how this is using feedback??

 

[D.A.(Tony)Stewart]

Since your primary and echo outputs are both impulses, a time domain filter based on a stable echo window can be gated off as done in Radar for early echoes rather than late echoes as in your case.

The system application needs more details.

 

[FvM]

Another question arose tho... why is this not a FIR filter???
You said it was an IIR filter, but i cant seem to understand how this is using feedback??

H(z)=1 + 0.25z^-Ne is the system transfer function, which is FIR

Hinv(z) = 1/(1 + 0.25z^-Ne) the inverted transfer function is an IIR filter

 

[pattalol]

H(z)=1 + 0.25z^-Ne is the system transfer function, which is FIR

Hinv(z) = 1/(1 + 0.25z^-Ne) the inverted transfer function is an IIR filter

yeah i understand that now by proving that the output is only delta[n] when connecting an IIR filter with H(z)=1/(1+0.25z^-Ne), so ty!
If i wanted to find the impulse response for the filter, what should i do??

If Ne = 1 it would be easy... just use the table; (-0.25)^n * u[n]... if Ne was 2 i could use partial fractioning to find the answer...
But in my case Ne= 2205 - so how do i do it then?

 

[FvM]

If z-domain transfer functions aren't descriptive for you, you can model the system transfer function and compensating filter with hardware blocks (delay Ne, factor 0.25, summer respectively substractor).

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