butterworth,bessel,Chebyshev

[walters]

How do i measure the cutoff point?

how do i measure the rolloff?

How do i measure the critical point?

Is butterworth,bessel,Chebyshev just different rolloff , and critical points ?
Whats the difference between these?

Does butterworth,bessel,Chebyshev have different resonance frequency?
and different phase angles/degrees?

Whats the different phase angles/degrees from each of these butterworth,bessel,Chebyshev?

 

[Optikon]

How do i measure the cutoff point?

how do i measure the rolloff?

How do i measure the critical point?

Is butterworth,bessel,Chebyshev just different rolloff , and critical points ?
Whats the difference between these?

Does butterworth,bessel,Chebyshev have different resonance frequency?
and different phase angles/degrees?

Whats the different phase angles/degrees from each of these butterworth,bessel,Chebyshev?

Some basic descriptions can be found here.

**broken link removed**

 

[audioguru]

How do i measure the cutoff point?
how do i measure the rolloff?

It depends on which test instruments are used.

How do i measure the critical point?

I have never heard of it.

Is butterworth,bessel,Chebyshev just different rolloff

Everyting shown in Optikon's tutorial is different about them.

critical points ?
Whats the difference between these?

I have never heard of them.

Does butterworth,bessel,Chebyshev have different resonance frequency?

They are lowpass or highpass filters that normally don't resonate. If their Q is too high then they resonate.

different phase angles/degrees?

Yes they are different.

Whats the different phase angles/degrees from each of these butterworth,bessel,Chebyshev?

It depends on how many stages and the frequency. The curves in Optikon's tutorial show the amount of phase-shift vs frequency for a single stage.

 

[theinfamousbob]

critical points ?
Whats the difference between these?

Do you mean the key points on a sine/cosine wave? For example, and axis cross or relative maxima or minima? I think that might be it....

*shrugs*

Hope that helps....

-Infamous

 

[walters]

Thanks guys for the help

How is the butterworth,bessel,Chebyshev phase shifts differ?

Whats the DB roll off differ from all these butterworth,bessel,Chebyshev?

Do i measure the BD "roll off" with a AC meter?

How do i tell its the roll off is 3bd or 6bd or 9db?

How do i tell if the filter is a butterworth,bessel,Chebyshev how would i know?

 

[audioguru]

Ho hum.

 

[walters]

ok

 

[_3iMaJ]

I don't know why I bother reading his posts anymore, everytime I'm finished I feel like I've lost a part of my life I'll never get back.

 

[walters]

why does a Butterworth filter have a Flatness in the passband?

why is a butterworth filter have a -20db decade/pole roll off?

why does a Bessel filter have a linear phase?

why does a Chebyshev have "ripples" in the passband?

 

[audioguru]

I also don't know why I bother reading his posts anymore. He doesn't learn anything. Maybe we are lousy teachers.

 

[walters]

Butterworth
1.) flat amplitude response
2.) Phase response is NOT linear
3.) phase shift is nonlinearly with frequency
4.) each frequency have a different time delay

Chebyshev
1.) overshoot and ripples
2.) Linear phase response

Bessel
1.) Linear phase response
2.) phase shifts are linear with frequency


All these types of filters are used for ONLY pulses wavefroms?

 

[walters]

Damping Factor- is just negative feedback?

Negative feedback changes the frequency response
and output voltage

Damping factor- is to just get a FLAT fresponse?

 

[walters]

Does the number of "poles" change the Cutoff"critical frequency?

Number of poles= roll off rate= change the Cutoff frequency?

Cascaded stages changes the roll off rate?

So whats the difference between a 8 pole filter VS a four cascading 2 pole filter stages ?

 

[audioguru]

You could learn this stuff or just try the circuits to see what happens.
I did both.

 

[bryan1]

Well here you go again Walters :cry: in 7 posts in this thread you've managed about 24 questions and a few negative posts. Remember back a few weeks ago and did anything of what we said sink in. :shock: or is this thread part of your 500,000 questions your bombarding us with. Any normal student would go to the library and read a book to learn or search the net.

 

[DigiTan]

You know, we could use this as a chance to test our training in this stuff. How does the saying go? "To teach is to learn?" I wanna teach, learning sucks. :lol:

Cascaded stages changes the roll off rate?

Yes, in fact it's not uncommon practice to cascade active filters until you have an acceptable roll-off.

Number of poles= roll off rate= change the Cutoff frequency?

I'm not certain about this one, but I think the poles positions and their real vs. imaginary status has the dominant effect. Don't quote me on that though.

Damping factor- is to just get a FLAT fresponse?

If you damping is sufficeintly high, the step response will be "flattened" and you'll have no ringing or overshoot on the output.

 

[walters]

Thanks guys for the help

 

[walters]

Whats the difference between a Sallen Key filter VS a 2 pole filter?


Whats the difference between the "Q" VS the Center frequency?

Q-is the "Ratio" of the center frequency to its bandwidth

Bandwidth- the range of frequency passing from input to output

Center frequency-

 

[Optikon]

Thanks guys for the help

Do you think you've been helped?

 

[Optikon]

Whats the difference between a Sallen Key filter VS a 2 pole filter?


-

Walters, filter topologies have poles & zeros (if you do not know what those are, you ought to study that first)

Sallen Key is a filter _topology_ that has 2 poles.

Comparing a topology to a 2 pole filter doesnt make sense unless you reveal what 2 pole filter you are comparing it to.

Your question might be

"what is the difference between a Sallen Key 2 pole filter and a Butterworth 2 pole filter"

for which, I would respond:

"Compare the frequency dependent transfer functions of the two topologies - that tells you everything."

You would have to ask a more specific question. AS is usually the case with you and why I seriously doubt you get much help to your questions.