# Questions tagged [causality]

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11 questions with no upvoted or accepted answers
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### What are the properties of continuous-time improper systems?

I am trying to better understand the properties of improper systems $H(s) = \frac{b(s)}{a(s)}$, for which the order of the numerator $b(s)$ is greater than the order of the denominator $a(s)$ (in the ...
• 51
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### Causal and Non-memoryless LTI sytems described by LCCDE

I was wondering about the nature of stable systems (in the BIBO sense) that are causal with memory for which we wish to represent them by LCCDE (if they may exist). How frequent do LCCDE exist such ...
• 129
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### How to determine which measurements cause which?

Suppose I have two sequences of measurements, $x_1[n]$ and $x_2[n]$ for $0 \le n \le N-1$. How do I determine if there is a causal relationship between the two? My first thought was, well... I can ...
• 25.9k
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### Stability of filters with negative phase delay, group delay, and positive phase

Lets assume I have an IIR filter with : bz = [1.0195 0 0]; az = [1 0.0166 0.0020]; fvtool(bz,az) The filter is stable as i can see. If you check the phase delay ...
• 105
1 vote
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### is this system linear? causal?

$$y(t) = \int_{t_0}^t u(\tau)\, d\tau + y(t_0)$$ I have trouble determining whether this system is causal or not and linear or not. I think this system is causal because it integrates input signals ...
• 31
1 vote
514 views

### Region of convergence of transfer function

I posted this question Mathematics SE and got no answer so I have posted it here. I learned in my signal processing class that an LTI system can be defined using a linear constant coefficient ...
25 views

### How to prove this system is not causal?

I set $x_1(t)=0$ and use the final rest property to get $y_1(t)=0$, and $y_2(t)=0$ for $t>1$. However, I cannot find general $y_2(t)$ for $x_2(t)$.
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### Stable and causal system

How many stable and causal systems with the same magnitude response are there? I know this relates to an all pass system for two rational transfer functions but am not sure about the specifics of this
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### Stability of $x(n) = A x(n-1)+b$

I am looking at the following system: $x(n) = A x(n-1) + b$ where x and b are vectors and A is a matrix. How can I derive the stability and causality conditions for such a system using Z transform? If ...