# Signal Distortion

1. Jul 31, 2009

### jeff1evesque

Statement:
Capacitance and inductance in a circuit allow different frequencies to travel with differing degrees of attenuation and phase shift. This causes the received signal to be different from the signal sent.

Question:
With low and high pass filters, we can control what kind of signal continues to the remaining portion of the circuit by attenuating either signal at high frequencies or at low frequencies [by the construction of resistors and capacitors]. Can someone explain to me how one would change the phase of the signal sent; more specifically
Statement:
In a purely resistive circuit, the signal received will be a scaled version of the signal sent $$\Rightarrow$$ no distortion.

Question:
Does this mean the amplitude of the signal received will smaller? I am not familiar with the term distortion, does that mean the signal will have the same wavelength?

Thanks,

JL

2. Aug 1, 2009

### Andrew Mason

The phase shift is the angle $\phi$ between voltage and current in an RLC circuit. If the circuit does not contain resistance the phase difference will be + 90 or -90 ($+- \frac{\pi}{2}$. In order to have a phase difference of something in between you need resistance.

See, for example: http://en.wikipedia.org/wiki/Electrical_impedance

AM

3. Aug 1, 2009

### jeff1evesque

That's all that's meant by it? Since we have a capacitor in the circuit, the wave that travels through the capacitor will have a voltage that is 90 degrees difference in phase? Is there any other implications- should the wave after going through the capacitor be 90 degrees out of phase with the wave coming into the capacitor?

So any kind of resistance will due (pure resistors, capacitors-with their impedance, inductors)?

Thanks,

JL