Recent content by bobbyk

Intresting question, which gave rise to much discussion! My only comment is about your assumption that it's an object's "center of gravity" that pulls you. Even in the static case you are not in general pulled toward the "center of gravity" of an object but to its "center of attraction"...

Guys, Mia Culpa! I must WITHDRAW my suggested "e-low-pass filter" because the Paley-Wiener Criterion doesn't apply to it! Its magnitide response is not "Square Integrable". I neglected to notice that that was a requierment. I told you I was not a mathematician! I'm sorry if I caused any...

OK, quadraphonics, thanks for your friendly and continued interest, and I now see that your concept of "delay" is much more useful than mine and I will discontinue using mine! What I really want to do, then, is to find a PHASE to accompany the GAIN of my e-ideal filter such that the impulse...

There must be a misunderstanding here, as a simple filter having a capacitor from input to output and a resistor from output to ground has, for an impulse input at t=0, an output containing an impulse at t=0. This is what I call zero-delay and the gain is certainly NOT flat.

qradraphonics: Thanks for your response and your interest! I'm sorry for using an undefined term such as "delay", but what is your definition of "nontrivial" ? I'm sure you know that there are causal filters whose impulse response to an impulse at t = 0 contain an impulse at t = 0. I...

It is my understanding that if the Paley-Wiener criterion for the GAIN is satisfied, then there is a PHASE associated with that GAIN such that the impulse response is casual and has ZERO delay. How do I find that PHASE? Thans for youir interest! bobbyk

Look, I'm not a mathematician, as you no doubt must realize (I don't even know how to do LaTeX!) and know nothing about the Paley-Wiener Criterion (although I did attend a lecture by Wiener once!). I saw it in a book by Chester Page and it intrigued me. I don't know what it says about the delay...

I'm only aware of one version of the criterion, namely: The N&S condition for a linear-time-invariant filter to have a causal response is that its Gain versus frequency, G(f), should satisfy: The integral from -infinity to +infinity of df*|log(G(f)|/(1+f^2) be < infinity. If you know...

Thanks for responding! I think this is fun! It is also, no doubt, well-known, but I haven't seen it anywhere. But a sinc() function is never causal, no matter what the delay, and I want a casual output function. There has to be one. Let's say the filter phase is zero over the entire...

It is well-known that the step-response of an ideal low-pass filter (Gain = 1 for f = 0 to F and = 0 for f = F to infinity) is non-causal, in that the output appeares before t = 0. But what if the filter's Gain is = 1 for f = 0 to F and = e (some small non-zero value) for f = F to infinity...

Thanks so much! This Is exactly the type of thing I'm looking for!

Yes, I understand what ASN is saying and he is wrong! You don't need to add anything to get a gain > 1. Even very simple passive RC networks have open-circuit voltage gains > 1. But I'm trying for a gain of 2.

This is not homework, but a question I have posed for myself. In a linear, passive, 3-terminal RC network for sinusoidal voltage input how many resistors and capacitors are required to give an open-circuit voltage gain of 2? I've found some very complicated networks, but I'd like to find...

Thanks, Dick, I will!

No, they don't give a reason - they just think it doesn't exist - just like you apparently do. Look, Dick, as you know, it's not a matter of opinion - either there is such a function or there isn't. I believe there is. Thanks for responding in a friendly manner! Bob