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# Nathan Kennedy

32 total contributions since 2017

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Question

FFT of a single sinusoid showing noise ?!
Hi, I have a signal which I am sampling so at least 10 wavelengths or 10 time periods can be plotted. It then works out how...

1 year ago | 2 answers | 0

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Question

uitable - how to extract negative numbers (but there is also empty cells) from a ui table in GUIDE
Hi, I am having issues extracting data from a ui table in GUIDE. The ui table has empty cells and also negative numbers. I ne...

1 year ago | 1 answer | 0

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Question

GUIDE - How to use variables that are calculated in Button 1, in Button 2?
I am finding it difficult to understand how this is done, I have read some posts and answers on it but I am even more confused w...

1 year ago | 1 answer | 0

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Question

Intermodulation products (third order) from MATLAB and FFT are too low
Hi, The intermodulation products I get from an FFT are too low but they scale correctly against my wanted frequency signal po...

1 year ago | 5 answers | 0

### 5

Intermodulation products (third order) from MATLAB and FFT are too low
Hi, Its attached. * It contains the controls at the start. * Then it has the transfer curve data, AM-AM and AM-PM. *...

1 year ago | 0

Question

Polyfit with odd powers only?
Hi, I am trying to get a polyfit with only odd powers - so polyfit will not work because it has odd and even. I do not ha...

1 year ago | 2 answers | 0

### 2

Incorrect phase from fourier transform
Hi David, Thanks. Answers accepted. I've rewritten my third order intercept code a few times and this is part of it, reconstruct...

1 year ago | 0

Question

Incorrect phase from fourier transform
Hi, * I make a few sinusoids of different frequencies with different phase offsets. * Add them to make a waveform * Fast F...

1 year ago | 2 answers | 0

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Question

Phase angle is producing an error
Hi, I am getting a phase error on my waveform it is not quite reaching +pi or -pi in some cases(not everytime which I find stra...

2 years ago | 0 answers | 0

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Question

Place polyfit values in a matrix using a loop
Hi I want to capture all the values from the polyfit function in a matrix when it is in a loop. for a=1:length(x) te...

2 years ago | 1 answer | 0

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Question

No Second Order Harmonics in FFT
Hi, I have a script that generates a waveform (sum of sinusoids) and puts it through an AM-AM transfer curve (the input ampli...

2 years ago | 0 answers | 0

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Question

How to represent waveform (sum of sinusoids) in complex notation
Hi, I have a sum sinusoids to make a waveform, each sinusoid has a different phase attached to it. clear f = ...

2 years ago | 1 answer | 0

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Question

Plot a circle and a vector moving around it
Hi Draw a circle, then plot multiple vectors from the origin to the outline of the circle angle = 0:0.05:2*pi x ...

2 years ago | 2 answers | 0

### 2

Find elements from A in B and get the index of found element in B
I am interested in what Jo says, but I don't think that's the issue? I have tried what others have written above and it does not...

2 years ago | 0

Question

Find elements from A in B and get the index of found element in B
Hi I have two arrays, A and B, A has 12,000 elements and B has 260,000 elements. I need to find every instance when an ele...

2 years ago | 5 answers | 0

### 5

Question

Adding Random phase causes fft anomalies?
Hi If I add random_phase to my waveforms then the fft goes skewy - basically it breaks down and is not producing what it shou...

2 years ago | 2 answers | 0

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Question

fft working but end time of waveform distorting result
Hi, I am having a problem that my amplitudes are being affected when I change the end time that my waveform is sampled for. ...

2 years ago | 0 answers | 0

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Question

Plotting a Surf of my waveform
Hi, my waveform is sampling = 1 / (1*10^6); t = 0: sampling :0.05 ; %Sample Rate f = (30 : 1 : 35)* (10^3); %Freque...

2 years ago | 1 answer | 0

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Question

GUIDE - add windowed tabs manually or in using this tool?
Hi, I have figure that is output that I made with GUI, it has push buttons, tables, plots etc.... but now I want to have mult...

2 years ago | 0 answers | 0

### 0

Question

Tricky frequency spacing loop
I have a tricky loop, well I think its quite tricky... maybe its not for you * I have 1000 Hz of bandwidth. * I need to p...

2 years ago | 0 answers | 0

### 0

Memory leak from waveform plotting at high frequency
No idea what you mean by that. It crashes withn range above about 1Khz for example 1Ghz to 1.1Gz. I just want to be able to p...

2 years ago | 0

Question

Memory leak from waveform plotting at high frequency
Hi I'm having problems with 16gb of RAM on my computer being taken up calculating the below. I know its because of t and ...

2 years ago | 3 answers | 0

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Question

Combine a waveform from a set of sine waves which are linearly increasing in frequency
Hi, I generate and plot multiple waveforms which have increasing frequency. I want to combine them at each time interval of t...

2 years ago | 1 answer | 0

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Question

String or Number to a time format
I have the following stored in an array called timearray thats been imported form a csv file 22:30:26:718 The format is ...

2 years ago | 1 answer | 0

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Question

Hi, If I create two arrays in MATLAB that represent and store the column name and row names of a table, I want to then find t...

2 years ago | 1 answer | 0

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Question

Array to table not working after forming matrix
altitude = [ 5 10 15 20 25 30 35 40 45 50 55 60 65 ]; flux_up = [ 35 55 80 110 125 130 140 150 155 175 225 275 325]; ...

2 years ago | 2 answers | 0