Why do we consider zero mean for gaussian noise in a communication channel?

In summary, the conversation discusses the concept of noise in communication channels and why it is commonly assumed to have a zero mean. The discussion also touches on the practicality and semantics of this assumption, as well as the effects of low frequency noise in analogue equipment.
  • #1
dexterdev
194
1
Hi all,
I got an idea why noise is having a gaussian pdf but didnot understood why it should be having zero mean. Why can't noise contain a dc content.

-Devanand T
 
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  • #2
in most cases we consider 0 mean awgn , is it so...
 
  • #3
dexterdev said:
Why can't noise contain a dc content.

DC component means that there is energy (power) permanently leaving the source, i.e. the source is "evaporating" so it would eventually seize to exist.
 
  • #4
FailedLaunch said:
DC component means that there is energy (power) permanently leaving the source, i.e. the source is "evaporating" so it would eventually seize to exist.

Can you explain in simple english (Iam not good in english). I didnot got the idea of evaporate and seize etc..
 
  • #5
Taking it back

FailedLaunch said:
DC component means that there is energy (power) permanently leaving the source, i.e. the source is "evaporating" so it would eventually seize to exist.
Actually, it looks like I'll need to take this explanation back since it doesn't appear to be to right reason while the used AWGN is zero-mean. :uhh:

Check also this thread: [thread=163759]White noise in communication channel[/thread]
 
  • #6
dexterdev said:
Hi all,
I got an idea why noise is having a gaussian pdf but didnot understood why it should be having zero mean. Why can't noise contain a dc content.

-Devanand T

Your question is quite a reasonable one. It is largely a matter of semantics and practicalities, I think. In all analogue equipment, you can expect very low rate drifting of DC levels and these will mostly be due to other effects (due to thermal variations of gain etc.) than the normal Gaussian Noise that you can also expect. Most analogue channels are deliberately made 'AC' coupled so there is a lower frequency limit, below which we are not particularly interested and it is not very relevant, in any case. Also, if you think of noise power in W/Hz, there is very little of it in a small fraction of a Hz, compared with normal signalling rates.
 
  • #7
Thankyou for your helpful replies. but what does "matter of semantics" mean
 
  • #8
dexterdev said:
Thankyou for your helpful replies. but what does "matter of semantics" mean

It refers to the meaning we attribute to words. We make 'assumptions' when we read some words but different people make different assumptions. Mostly, we take it for granted that channels are AC coupled because DC is too difficult. (I can't think of an example, in fact. Now that's a challenge for you all.)
 
  • #9
thanks again sir
 

1. What is zero mean in a gaussian noise distribution?

In a gaussian or normal distribution, the mean represents the average or central tendency of the data. A zero mean indicates that the data is evenly distributed around the mean, with an equal number of values above and below the mean.

2. Why is zero mean important in a communication channel?

In a communication channel, zero mean is important because it represents the absence of a signal or noise. This means that the channel is not biased towards any particular value, making it easier to detect and remove noise from the signal.

3. How does zero mean affect the reliability of a communication channel?

A zero mean in a communication channel is desirable because it allows for more precise and accurate signal detection. With a zero mean, the signal-to-noise ratio is maximized, making it easier to distinguish the signal from the noise and improving the overall reliability of the channel.

4. What happens if the mean is not zero in a gaussian noise distribution?

If the mean is not zero in a gaussian noise distribution, it can introduce bias into the data and impact the accuracy of signal detection. This can result in errors and decreased reliability in the communication channel.

5. How is the mean determined in a communication channel?

The mean in a communication channel is determined by the properties of the noise source and the characteristics of the channel itself. It can also be adjusted or controlled through various methods, such as filtering or equalization, to achieve a desired zero mean value.

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