A Quadrature Signals Tutorial: Complex, But Not Complicated

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Complex Digital Signal Processing in Telecommunications

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Hi, Can anyone correct the difference between Digital and Discrete signal? I feel, digital signals can be one and zero. But discrete signal can be any numeral, say one, two or ten. The difference between Analog and Discrete/Digital signal is that signals are periodic in Digital, while analog signals are continuous. Please guide me. Regards, Ranga.

```
Ranga wrote:
> Hi,
>
> Can anyone correct the difference between Digital and Discrete signal?
>
> I feel, digital signals can be one and zero.
>
> But discrete signal can be any numeral, say one, two or ten.
>
> The difference between Analog and Discrete/Digital signal is that
> signals are periodic in Digital, while analog signals are continuous.
>
> Please guide me.
>
> Regards,
> Ranga.
A digitized signal is otained most of the time by sampling a discrete
signal,
once sampled, the signal is digitized (using ADC). For example,
in telephony, the signal is sampled at a 8Khz rate, digitized on
13bits,
and after digitally compressed using mulaw or alaw.
Gerard
```

"Gerard Lyonnaz" <g...@hp.com> wrote in message news:4...@hp.com... > Ranga wrote: > >> Hi, >> >> Can anyone correct the difference between Digital and Discrete signal? >> >> I feel, digital signals can be one and zero. >> >> But discrete signal can be any numeral, say one, two or ten. >> >> The difference between Analog and Discrete/Digital signal is that >> signals are periodic in Digital, while analog signals are continuous. >> >> Please guide me. >> >> Regards, >> Ranga. > > A digitized signal is otained most of the time by sampling a discrete > signal, > once sampled, the signal is digitized (using ADC). For example, > in telephony, the signal is sampled at a 8Khz rate, digitized on > 13bits, > and after digitally compressed using mulaw or alaw. > Gerard > Hmmmmm..... I'd say that a discrete signal is a sequence of samples - no matter how those samples occur or how they are represented. They could be generated by a mathematical expression, etc. There's lots of analysis and texts on discrete systems - without mention of how the representation of the values of the samples is implemented. There are also lots of examples of discrete systems that use "analog" storage mechanisms - like charge-coupled devices, bucket-brigade or switched capacitor filters, etc. A digital signal is necessarily discrete. To make it digital as well means the values are described using finite precision arithmetic. The sample rate or interval, uniform or nonuniform has nothing to do with it. I don't agree that: "A digitized signal is otained most of the time by sampling a discrete signal" That's because sampling is the process that might be used to generate the discrete signal in the first place. Then you need to talk about representation and storage. Rather, I'd say that "A digitized signal is obtained most of the time by sampling a continuous signal (as with a sample-hold) and storing the result using finite precision arithmetic (as out of an ADC) - as would be found in a digital computer." The latter is where the term "analog to digital converter" takes its meaning. Fred

On 11 Oct 2004 23:45:45 -0700, r...@rediffmail.com (Ranga) wrote: >Hi, > >Can anyone correct the difference between Digital and Discrete signal? 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. hth.

Hi, Read the First chapter in the book " Digital Signal Processing" A Computer based approach by SK Mithra, TMH. Sathish "Ranga" <r...@rediffmail.com> wrote in message news:6...@posting.google.com... > Hi, > > Can anyone correct the difference between Digital and Discrete signal? > > I feel, digital signals can be one and zero. > > But discrete signal can be any numeral, say one, two or ten. > > The difference between Analog and Discrete/Digital signal is that > signals are periodic in Digital, while analog signals are continuous. > > Please guide me. > > Regards, > Ranga.

"Sathish" <s...@de.bosch.com> wrote in message news:<ckgp47$gt6$1...@ns2.fe.internet.bosch.com>... > Hi, > > Read the First chapter in the book " Digital Signal Processing" A > Computer based approach by SK Mithra, TMH. > > Sathish > > "Ranga" <r...@rediffmail.com> wrote in message > news:6...@posting.google.com... > > Hi, > > > > Can anyone correct the difference between Digital and Discrete signal? > > > > I feel, digital signals can be one and zero. > > > > But discrete signal can be any numeral, say one, two or ten. > > > > The difference between Analog and Discrete/Digital signal is that > > signals are periodic in Digital, while analog signals are continuous. > > > > Please guide me. > > > > Regards, > > Ranga. Hi, Discrete Signals : Obtained by sampling the analog signal at disctrete instants of time. However the magnitude of the discrete signals is same as that of the analog signal at that point in time. (Discrete only in time) Digital Signal : When the magnitude of the discrete signal is quantized to the the nearest integer, we get a digital signal. (Which is both discrete in magnitude & time) Example: Say, after sampling the analog signal, we get discrete signal as below x[0] = 0 x[1] = 0.9 x[2] = 1.8 x[3] = 2.6 x[4] = 2.1 x[5] = 1.8 .... When you want to digitize this signal, you pass it through the ADC & the output would be as below. x[0] = 0 x[1] = 1 x[2] = 2 x[3] = 3 x[4] = 2 x[5] = 2... The above output depends upon the resolution of the ADC . More the resolution, less the quantization error. I hope this helps your question. Regards Sandeep

On 12 Oct 2004 20:29:41 -0700, s...@yahoo.com (Sandeep Chikkerur) wrote: (snipped) > >Hi, > >Discrete Signals : >Obtained by sampling the analog signal at disctrete instants of time. >However the magnitude of the discrete signals is same as that of the >analog signal at that point in time. >(Discrete only in time) > >Digital Signal : >When the magnitude of the discrete signal is quantized to the the >nearest integer, we get a digital signal. >(Which is both discrete in magnitude & time) > >Example: >Say, after sampling the analog signal, we get discrete signal as below >x[0] = 0 >x[1] = 0.9 >x[2] = 1.8 >x[3] = 2.6 >x[4] = 2.1 >x[5] = 1.8 .... > >When you want to digitize this signal, you pass it through the ADC & >the output >would be as below. >x[0] = 0 >x[1] = 1 >x[2] = 2 >x[3] = 3 >x[4] = 2 >x[5] = 2... > >The above output depends upon the resolution of the ADC . >More the resolution, less the quantization error. > >I hope this helps your question. > >Regards >Sandeep Hi, very nice explanation! This is good. [-Rick-]

```
Rick Lyons wrote:
> On 12 Oct 2004 20:29:41 -0700, s...@yahoo.com (Sandeep
> Chikkerur) wrote:
>
> (snipped)
>
>>Hi,
>>
>>Discrete Signals :
>>Obtained by sampling the analog signal at disctrete instants of time.
>>However the magnitude of the discrete signals is same as that of the
>>analog signal at that point in time.
>>(Discrete only in time)
>>
>>Digital Signal :
>>When the magnitude of the discrete signal is quantized to the the
>>nearest integer, we get a digital signal.
>>(Which is both discrete in magnitude & time)
>>
>>Example:
>>Say, after sampling the analog signal, we get discrete signal as below
>>x[0] = 0
>>x[1] = 0.9
>>x[2] = 1.8
>>x[3] = 2.6
>>x[4] = 2.1
>>x[5] = 1.8 ....
>>
>>When you want to digitize this signal, you pass it through the ADC &
>>the output
>>would be as below.
>>x[0] = 0
>>x[1] = 1
>>x[2] = 2
>>x[3] = 3
>>x[4] = 2
>>x[5] = 2...
>>
>>The above output depends upon the resolution of the ADC .
>>More the resolution, less the quantization error.
>>
>>I hope this helps your question.
>>
>>Regards
>>Sandeep
>
>
> Hi,
>
> very nice explanation! This is good.
Except, to pick a nit, digital signals can also be, and sometimes are,
generated by computation.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
```

```
Jerry Avins wrote:
(snip on discretizing, digitizing and sampling)
> Except, to pick a nit, digital signals can also be,
> and sometimes are, generated by computation.
I have a whole CD of audio test signals that I believe
was generated by computation. If you want a sine wave
it is most accurate to compute it than digitize an
analog wave.
For a philosophy question, is it sampling and digitizing
a virtual analog signal?
-- glen
```

```
glen herrmannsfeldt wrote:
>
>
> Jerry Avins wrote:
>
> (snip on discretizing, digitizing and sampling)
>
>> Except, to pick a nit, digital signals can also be,
>
>> and sometimes are, generated by computation.
>
> I have a whole CD of audio test signals that I believe
> was generated by computation. If you want a sine wave
> it is most accurate to compute it than digitize an
> analog wave.
>
> For a philosophy question, is it sampling and digitizing
> a virtual analog signal?
I guess that to some extent, it depends on the actual code.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
```