Are those sentences true or false?

[ednan]

Plz tell that wheather it is true or false....

(i) A closed - loop control system is usually more accurate than an open loop system.
(ii) Feedback is sometimes used to improve the sestivity of a control system...
(iii)If an open loop system is unstable then applying feedback will always improve its stability.
(iv)Feedback can incease the gain of a system in one frequency range but decrease in another.
(v)Nonlinear elements are sometimes intentionally introduced to control system to improve its performance.
(vi)Discrete-data control system are more susceptible to noise due to the nature of its signals.

 

[Kral]

Re: True or false.

ednan,
I'm assuming that when you use the term "feedback" that you mean "negative feedback". With that in mind:
i true
ii False Negative feedback always reduces the sensitivity.
iii False However, properly designed compensation networks can allow negative feedback to stabilize a system that is unstable without negative feedback.
iv true
v true For example, a limiter can prevent saturation of the electronics.
vi false. Discrete Data (Digital) systems have high noise immunity.
Regards,
Kral

 

[reza17]

Re: True or false.

(i) A closed - loop control system is usually more accurate than an open loop system.

TRUE

(ii) Feedback is sometimes used to improve the sestivity of a control system...
TRUE

(iii)If an open loop system is unstable then applying feedback will always improve its stability.
FALSE

(iv)Feedback can incease the gain of a system in one frequency range but decrease in another.

FALSE

(v)Nonlinear elements are sometimes intentionally introduced to control system to improve its performance.

TRUE
(vi)Discrete-data control system are more susceptible to noise due to the nature of its signals.

I DONT KNOW THIS

 

[A.Anand Srinivasan]

True or false.

reza17 is correct..... for the (vi) it is false....

 

[KMoffett]

Re: True or false.

reza17,

(iv)Feedback can incease the gain of a system in one frequency range but decrease in another.

Seems like on the face of it, this is True, as Kral said.

Take a "system", an op-amp, with a capacitor in the negative feedback loop. At frequency X it has unity gain...by my definition. In the frequency range [f<X] the gain will increase with a decrease in frequency. In the frequency range [f>X] the gain will decrease with a increase in frequency.

Ken

 

[reza17]

Re: True or false.

reza17,

(iv)Feedback can incease the gain of a system in one frequency range but decrease in another.

Seems like on the face of it, this is True, as Kral said.

Take a "system", an op-amp, with a capacitor in the negative feedback loop. At frequency X it has unity gain...by my definition. In the frequency range [f<X] the gain will increase with a decrease in frequency. In the frequency range [f>X] the gain will decrease with a increase in frequency.

Ken

ok

 

[A.Anand Srinivasan]

True or false.

KMoffett you got a point there..... i didnt notice that.... i too agree that feedback can cause change in gain wrt freq...

 

[gabin]

Re: True or false.

KMOFFET you have got a right point. I agree to rezza.