Still in my Bachelor of Electrical Engineering. I'm new to signal processing, but trying my best. I'm doing a project right now and try to get used to MATLAB.

Re: Digital Modulation Methods

Reply posted 4 years ago (10/22/2017)
Yeah, the constellation diagram is the first part of the task. The modulation symbols have to be labelled as you can see in the photograph. But I have no clue about...

Digital Modulation Methods

New thread started 4 years ago
So I'm currently working on preparatory lab tasks, which, unfortunately, I cannot solve. For an 8-PSK modulation I consider the bit sequence 011 111 001 000 ,...

Re: Complex envelope and analytic signals.

Reply posted 5 years ago (03/26/2017)
you're right, I messed up the frequencies. I have corrected it in my original post.Unfortunately, the phases are still not equal.t is a vector of time, but for the...

Re: Complex envelope and analytic signals.

Reply posted 5 years ago (03/26/2017)
allright, thanks Fred! - I have edited my question and I hope it is more clear now - although I admit the code lines look a little confusing

Complex envelope and analytic signals.

New thread started 5 years ago
I can't get my head around the complex envelope and analytic signals. I know I have asked this before, but I considered the problem again and to me it hasn't been...
thx very much, it does help!
The AM/PM curve of a power amplifier gives the difference in phase of the output and the input signal in dependence of the input power/ amplitude. Now, this phase...
Thanks Fred, this really helps! But I am still a little bit confused: Since you asked for a definition of the one-sided Fourier transform, I started looking...
The spectrum of an analytic signal equals twice the spectrum of its real part for positive frequencies and it is zero for negative frequencies. Now, I wonder: When...

Re: AM/PM of a RF power amplifier

Reply posted 5 years ago (02/21/2017)
Did you mean to ask me that question? I don't see the link to my original question. And I have no clue about it. I mean, I'm grateful if you are trying to give me...
I can extract the amplitude and the phase from the complex envelope representation. This can easily be done with abs() and phase() command in Matlab. I think it...

Re: AM/PM of a RF power amplifier

Reply posted 5 years ago (02/17/2017)
great, thanks !

AM/PM of a RF power amplifier

New thread started 5 years ago
The AM/PM characteristic of a RF power amplifier graphs the phase difference of the input and the output signal in dependance of the amplitude of the input signal. I...
Ya, I thought so too. It is kind of urgent now, however. Can you still explain to me where I find the AM/PM in my mathematical expression? I don't know what you...
ok, let me see: A power spectrum cannot have negative components. That means, with the sin(2wt) term, I am substracting a positive power. Leaving out this term...
so, does distortion mean "distorted from the linear transfer characteristic" ?
the sine-wave at 2wt is also phase shifted by pi/2. Is this the phase distortion ? .. If I would draw the power spectrum of the output signal, would the term at...
thx, this really helps! I have tried both with a sine and a cos two-tone signal: x(t) = sin(wt) + a * sin(wt)^2x(t) = sin(wt) + a/2 * (1 - cos(2 wt) ) x(t) =...
Harmonics and intermodulation products do not occur in ideally linear devices. Why do they occur in nonlinear devices? I am referring to amplifiers. It must be linked...
this is a great answer, thx Michael!still, I have tried out the matlab2tikz script, which can be downloaded at Matlab File Exchange. When I create the figure in...
I am trying to add a Matlab graphic to a LaTeX document. I know there are various ways of achieving this and I hope somebody here can explain it to me.  I have...
wow, this is so much input, thank you guys so much! This should be the correct result then: The equivalent lowpass, or complex envelope representation is often...
Ok. Sorry, I'm a little slow on this topic. If I understand correctly, by shifting a bandpass signal down to baseband, half of the information will be in the negative...
Thx Tim, I feel like I am slowly getting there, but I'm not quite there yet. So from your nice exponential formulas trick, I see that you are basically just shifting...
I don't know how to show that these signals are not equal, but here's my intuition: The original two-tone signal consists of two cos-waves at different frequencies....
Is this, what you mean by re-casting: Is this still the same two-tone signal then?
I know I have been asking a lot about amplifiers, this will be the last question, I promise! So, any single-tone signal can be represented as an equivalent lowpass:...

Re: harmonic distortion of a single-tone excitation

Reply posted 5 years ago (02/08/2017)
allright, thx! I don't have software to validate your answer, but it is what I figured.
I consider a single-tone input to a nonlinear amplifier. I know, the nonlinearity will produce additional harmonic components at the output. I also know, the amplitude...
thanks for your reply, Tim! The paper is about TWTAs. And the formula is stated to be valid for a two-tone input. Let me see, if I understand your reply correctly:...
I consider a two-tone input to a nonlinear amplifier. In a paper I have read (unfortunately I cannot upload the paper), there is a formula mentioned for the calculation...

Re: How to create a vector graphic of a block model

Reply posted 5 years ago (02/06/2017)
allright, thanks so much!

Re: How to create a vector graphic of a block model

Reply posted 5 years ago (02/05/2017)
hey, thanks for your answer! I have tried out both LibreOffice Impress and Inkscape. I have exported my Inkscape drawing as an .eps file. I have exported the LibreOffice...

Re: Why do we want an amplifier to be linear?

Reply posted 5 years ago (01/31/2017)
So, I am currently working on a paper. I want to give a short introduction to ideal linear amplifiers. I was thinking about sth. like: An ideal linear amplifier...

Re: Why do we want an amplifier to be linear?

Reply posted 5 years ago (01/31/2017)
ok, thank you talldsp!  So, my statement g P_in = P_out ist actually wrong. It has to be  g V_in = V_out instead.  Now, in this case I have another question:...

Why do we want an amplifier to be linear?

New thread started 5 years ago
An ideal linear amplifier relates the input power to the output power of a signal by a proportional gain factor.  Is this a valid statement? Anyways, since it...

Re: How to create a vector graphic of a block model

Reply posted 5 years ago (01/31/2017)
allright, thanks! I will consider using TikZ, but since it's kind of urgent, I will probably stick with Visio then.
Ok, this is not a question related to digital signal processing. Sorry about that. Maybe you can still help: I want to create the following three graphics myself: I...

TWTAs as compared to SSPAs

New thread started 5 years ago
I have a few ( I assume very basic) questions about high frequency amplifiers in satellite communication. So, the traveling-wave tube is an amplifier which can...

Re: Preemphasis Filter Design

Reply posted 5 years ago (01/19/2017)
thank you so much, dudelsound! I finally got it. ... now I will have to find a way of implementing it in matlab.

Re: Preemphasis Filter Design

Reply posted 5 years ago (01/17/2017)
ok. So, I hope I understand correctly: I want my filter to shift my nonlinear characteristics towards the center characteristic. E.g. the characteristic at f1 =...

Re: Preemphasis Filter Design

Reply posted 5 years ago (01/16/2017)
yeah, sorry to be so unclear about my question, I had some troubles understanding the problem. I think I got it now: I want to characterize a nonlinear amplifier....

Re: Preemphasis Filter Design

Reply posted 5 years ago (01/16/2017)
ok. I am given 5 different AM/AM characteristics (as a table, from which I can of course plot the figures). And I want to use Matlab in order to tell what results...

Re: Preemphasis Filter Design

Reply posted 5 years ago (01/16/2017)
Alltogether, I am given the AM/AM characteristics at 5 different frequencies. So I think I can set up a modell describing the nonlinearity in the range of these...

Re: Preemphasis Filter Design

Reply posted 5 years ago (01/16/2017)
you're right, the plot shows the AM/AM characteristic of a nonlinear amplifier and I am trying to linearize it using the "Poza Sarkozy Berger modell". You can find...

Preemphasis Filter Design

New thread started 5 years ago
Consider the following characteristic of a nonlinear amplifier for two different frequencies: I want to design a filter which shifts the green characteristic horizontally...
Hey, I'm absolutely new to signal processing, so please take it easy on me when I say sth. stupid ;-)Consider the following problem: I'm given a multicarrier input...

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