Question

1. What is RC filter? Why do we use RC filter in communication system design?

2. What is Roll off factor of an RC filter? How much of a typical value does it takes?

3. What is filter delay? How much of a typical filter delay is there for a FIR filter?

Answer 1

Answer)

1) We have 2 types of RC Filter:

One is the low pass filter which is a filter circuit and has a resistor as well as a capacitor that would pass via low latency signal and blocks the high-frequency signal and on the other hand, it is the high pass RC filter which would only pass the high-frequency signal, as well as its circuit, are mostly made of resistor and capacitor.

We mostly use it in communication as the capacitor would help in giving the high resistance to that of the DC signal or the low frequency while it also would provide the low resistance to that of the high-frequency signal.

This also helps in reducing the treble in the sound during a communication system design.

2) The roll Off factor is defined to be the symbol rate when it decreases which defines the excessive bandwidth which can be lowered in a filter with regards to a response which is elongated impulse.

There is this first-order network like that of the RC circuit which would have the roll off of 20 dB/decade which is mostly equivalent to 6dB/octave.

3) Filter delay is defined to be the filtering of the signal which would have the delay where the output signal gets shifted with regards to time and with that of the input. The delay could be rectified with the help of shifting the signal in time.

So as to find the amount of delay by the filter there is a formula which is to be used where FIR filter is to be used and it has N taps, where the delay is to be measured as (N-1) / (2*Fs) wherein F is defined to be the sampling of the frequency.