Recent content by Natalie Johnson

The complex exponential form of cosine cos(k omega t) = 1/2 * e^(i k omega t) + 1/2 * e^(-i k omega t) The trigonometric spectrum of cos(k omega t) is single amplitude of the cosine function at a single frequency of k on the real axis which is using the basis function of cosine, right? The...

I have a dBW value and dBW I understand to normally be given as representing a RMS Power (however this is not specificically ever stated and I am told its just assumed?) from dBW to Watts = 10^(dBW/10) This then gives RMS power in Watts At what point do I convert this from a RMS to a peak...

I have a MATLAB script for modelling a two tone signal (a sum of two sinusoids) going through a non linear transfer function (such as an amplifier). The amplitude of a signal is amplified non linearly, and also the phase is modified depending on the input power of the signal. The two sinusoids...

Hi, I am going around in circles, excuse the pun, with phasors, complex exponentials, I&Q and polar form... 1. A cos (ωt+Φ) = Acos(Φ) cos(ωt) - Asin(Φ)sin(ωt) Right hand side is polar form ... left hand side is in cartesian (rectangular) form via a trignometric identity? 2. But then...

Further to my previous post. He also says on page 561 Chapter 30 'Complex numbers' http://www.dspguide.com/ch30.htm Complex sinusoids must have the same frequency to be added ... which is not the case for real sinusoids? I mean I can add two sinusoids of different frequencies quite easily in...

Yes this is it. He gives each chapter as a PDF for free on the site and its got many reviews on amazon .com He does mention there is two ways to use complex numbers and sinusoids, equivalence and substitution and he says that entire chapter will be in regard to substitution on pg 558, second...

Yes the linear system is being represented as a complex sinusoid

DSP Guide .com has the highly rated textbook for digital signal processing. Chapter 30 pg 561 on Complex Numbers http://www.dspguide.com/ch30.htm (chapters are free to download) Hes talking about representing sinusoids with a complex number. Author states "Multiplying complex numbers A and...

Its from dsp guide.com. Its got massive amazon reviews on the usa site and from chapter 8 onwards its really relevant to all this. The author gives the pdf for free. The frequency domain goes from 0 to N/2 but the author says with neg frequencies its double this and is then periodic. I think...

Is the mathematical definition in that section comparable to what I have written in my guess explanation? Because section 4.4 only shows the frequency spectrum is periodic... Also, that mathematical explanation in section 4.4, it has k+N ... but the values of k only go from 0 to N/2 (0 to...

https://en.wikipedia.org/wiki/Discrete_Fourier_transform Why is the signal obtained from a DFT periodic? The time signal x[n] is finite and the number of sinusoids being correlated with it is finite, yet its said the frequency spectrum obtained after the DFT is periodic. I've also read the...

Hm okay I will do some more investigation. By the way, this is not using a Spectrum Analyser, its using MATLAB script and their FFT function and the transfer curve is a polynomial. The sine waves are fed into the polynomial and FFT used on output

It does not mention which to use

It affects the location of intercept (co ords) and yes its log log plot

Hi, I have a tough or straight forward question... please can someone share knowledge I have two sine waves at different frequencies, my fundamental frequencies, and they are summed together to produce a signal. This signal is put through a non linear transfer curve of an amplifier, which is...