Register to reply

One sided noise spectral density VS double sided noise spectral density

by unseensoul
Tags: density, double, noise, sided, spectral
Share this thread:
Apr5-11, 04:47 PM
P: 47
No is the one sided noise spectral density in communication systems. N is the double sided noise spectral density.

The relationship between them is given by 2N = No but I don't understand why it is like that. Why isn't it N = 2No instead?!
Phys.Org News Partner Engineering news on
Tiny UAVs and hummingbirds are put to test
Britain to trial driverless cars from 2015
NIST corrosion lab tests suggest need for underground gas tank retrofits
May6-11, 06:20 PM
Sci Advisor
PF Gold
P: 2,063
A complex signal like [tex]\exp{i\omega_0 t}[/tex] has a one-sided spectrum, in this case [tex]\delta(\omega-\omega_0)[/tex]. Its real counterpart [tex]\cos{\omega_0 t}[/tex] has the two-sided spectrum


The same power is spread in the real-signal case over positive and negative frequencies, each of which is half as large as the complex spectrum.

When you talk of the power spectral density (PSD) of thermal noise, it again matters whether you are using a real or a complex representation. Audio engineers often use the former, for instance, communications engineers generally the latter. For white noise where the PSD is a constant, and using your notation where N is two-sided and N0 is one-sided, they are related by N0 = 2N.

Register to reply

Related Discussions
Spectral density questions Electrical Engineering 1
Spectral density Electrical Engineering 1
Spectral density General Physics 3
Spectral density General Physics 0
Spectral density General Physics 0