Power Spectral Density

[NeedToKnow]

Hi,

Anyone uses MathCAD to calculate PSD for a time domain signal before?

[Luc_Meekes-disa]

This may be of use to you:
http://collab.mathsoft.com/~Mathcad2000/read?124920,8

Success!
Luc

[ptc-1368288]

On 9/25/2009 6:26:21 AM, lcpoon wrote:
>Hi,
>
>Anyone uses MathCAD to
>calculate PSD for a time
>domain signal before?
_________________________

"In statistical signal processing and physics, the spectral density, power spectral density (PSD), or energy spectral density (ESD), is a positive real function of a frequency variable associated with a stationary stochastic process, or a deterministic function of time, which has dimensions of power per Hz, or energy per Hz. It is often called simply the spectrum of the signal. Intuitively, the spectral density captures the frequency content of a stochastic process and helps identify periodicities".
...................

With such a vague definition and no work sheet of what PSD or simply spectrum mean to you, i.e: no project description then you had no reply as to what do you want. Do you have a vector of values

jmG

[RichardJ]

On 9/25/2009 6:26:21 AM, lcpoon wrote:

>Anyone uses MathCAD to
>calculate PSD for a time
>domain signal before?

Yes. How easy that is depends on the data.

If you could be more specific with the question, we could be more specific with the answer.

Richard

[NeedToKnow]

Attached is the worksheet. I would like to get the PSD for the sampled data output (SDO) after the quantizer.

[ptc-1368288]

On 9/26/2009 7:26:26 AM, lcpoon wrote:
>Attached is the worksheet. I
>would like to get the PSD for
>the sampled data output (SDO)
>after the quantizer.
______________________________

What you are looking for does not add up !

"Sampled data" are already digitized, otherwise you wouldn't have data, then quantization does not apply anymore because quantization is part of the digitization process itself. Apply PSD on the vector of the collected data which vector of data is "quantized/digitized".

jmG

[ptc-1368288]

On 9/26/2009 10:46:28 AM, jmG wrote:
>On 9/26/2009 7:26:26 AM, lcpoon wrote:
>>Attached is the worksheet. I
>>would like to get the PSD for
>>the sampled data output (SDO)
>>after the quantizer.
>______________________________
>
>What you are looking for does not add up
>!
>
>"Sampled data" are already digitized,
>otherwise you wouldn't have data, then
>quantization does not apply anymore
>because quantization is part of the
>digitization process itself. Apply PSD
>on the vector of the collected data
>which vector of data is
>"quantized/digitized".
>
>jmG
>===============================

Read + ...

In statistical signal processing and physics, the spectral density, power spectral density (PSD), or energy spectral density (ESD), is a positive real function of a frequency variable associated with a stationary stochastic process, or a deterministic function of time, which has dimensions of power per Hz, or energy per Hz. It is often called simply the spectrum of the signal. Intuitively, the spectral density captures the frequency content of a stochastic process and helps identify periodicities.

The PSD is the Fourier transform of the autocorrelation function, R(�), of the signal if the signal can be treated as a wide-sense stationary random process.[4]

http://www.delmarnorth.com/namaste/requirements/Namaste_Link_Analysis.pdf

Mathcad implementation [Signal Processing]

pspectrum(x, n, r, [w])
coherence(x, y, n, r, [w])
cspectrum(x, y, n, r, [w])
snr(x, y, n, r, [w])

The corresponding work sheet added.
If you are in that kind of stuff,
better download the extension pack !

jmG

[NeedToKnow]

Hi Jim G,

I attached here the diagram for your reference. Basically, the analog signal (a sinusoidal voltage signal at 48kHz with noise of 100dB down) is sampled at 48MHz. Please note that the sampler is a analog part where I defined its output as SDI (not yet digitized). SDI is then goes through a 9 level quantizer and the output (digitized) is named as SDO.

[ptc-1368288]

On 9/27/2009 10:12:37 AM, lcpoon wrote:
>Hi Jim G,
>
>I attached here the diagram
>for your reference. Basically,
>the analog signal (a
>sinusoidal voltage signal at
>48kHz with noise of 100dB
>down) is sampled at 48MHz.
>Please note that the sampler
>is a analog part where I
>defined its output as SDI (not
>yet digitized). SDI is then
>goes through a 9 level
>quantizer and the output
>(digitized) is named as SDO.
_____________________________

Not clear your "9 levels " ! ! !

You probably meant 2^9 . Whatever is SDI, you won't have enough values to process and convert back DAC to reconstruct. Slicing the sausage in 9 pieces does not feed 9 cats unless the sausage is very large and the cats very small. Whatever, that's what it is in demo. If you intend to deal with that kind of stuff: purchase the extension pack in order to follow more help from collabs.

jmG

[ptc-1368288]

On 9/27/2009 10:12:37 AM, lcpoon wrote:
>Hi Jim G,
>
>I attached here the diagram
>for your reference. Basically,
>the analog signal (a
>sinusoidal voltage signal at
>48kHz with noise of 100dB
>down) is sampled at 48MHz.
>Please note that the sampler
>is a analog part where I
>defined its output as SDI (not
>yet digitized). SDI is then
>goes through a 9 level
>quantizer and the output
>(digitized) is named as SDO.
_____________________________

I have no interest in the particular project, just in PSD in general. It is done as demo attached, but it needs the Mathcad built-in function. What that means for you: red if you don't have the "Signal" extension pack.

jmG