my professor said that everything in nature is on continuous time domain (continuous signal) and there is no discrete signals. i too know that do you have any idea that why discrete signal are not in nature .i am expecting geeky answers about this.Thank you

 

Your professor is wrong -- but only in the fine print. Some things in nature are inherently discrete (quantized). How much charge an object has is an integer multiple of the charge on an electron (subatomic particles notwithstanding, which are still quantized). But on a macro scale, the quantization of things is so fine that it might as well be continuous. Other things are inherently continuous, such as distance or time (although some physical theories postulate quanta for these, too).

 

Your professor is right and wrong.

I made the statement in another thread that all digital signals are analog.
What both your professor and I are referring to are electrical signals such as current or voltage.

Of course you can find many things in nature that are discrete.

 

I made the statement in another thread that all digital signals are analog.

what i am asking is about discrete signals not digital signal.

could some give me example for discrete signals and digital signals?

 

Hello,

Read this: http://www.dsprelated.com/showmessage/1220/1.php

This was found using the following query:
discrete signals

Bertus

 

Any kind of detector than detects the presence of particles such as alpha, beta, gamma rays or photons will produce a discrete signal.

 

Hello,

Read this: http://www.dsprelated.com/showmessage/1220/1.php

Bertus

Interesting. One of the responses was:

All discrete are digital but not vice versa.

 

@bertus

In this context, signals can be quantized and sampled. Not all sampled
signals are quantized (ie signals in a switched capacitor filter) and
not all quantized signals are sampled (output of an analog
comparator). A discrete signal is one which is sampled but not
necessarily quantized. A digital signal is one which is sampled and
quantized. So all discrete signals are digital but not vice versa.
An analog to digital converter is a good example of a system where all
domains appear at once and shows how processing can be done at all
domains. The analog signal is conditioned (possibly with a low pass
and/or an analog matched filter) at the input, applied to a
sample-hold filter with analog values and then quantized with
comparators set at different thresholds (in a flash converter). These
blocks can be ordered differently based on your requirements.

This is one of reply to the question i am just quoting the lines from the above paragraph that i feel wrong

not all quantized signals are sampled

quantisation can only be done after sampling,right?

So all discrete signals are digital but not vice versa.

he is saying in reverse,what i feel right is all digital signals are discrete signal ,is that right?