Export Spectrum Analyser trace to workspace or file

Hi, as the title says, I want to find out how to export the trace (dBm) from a Spectrum Analyser, in Simulink, to either the workspace or preferably to an external (EXCEL spreadsheet) file ?

[Derek Eccles]

Assuming it is possible to export the dBm trace from the Simulink spectrum analyzer to an excel spreadsheet, please see my latest attempts :

>> sablock = fsk, '/Spectrum Analyzer' ;

sablock =

0

4

0

0

0

0

1

>> config = get.param ( [sablock],'Scope Configuration');

Undefined variable "get" or class "get.param".

>> config = get_param ( [sablock],'Scope Configuration');

Error at element 1 of first input to get_param:

block_diagram does not have a parameter named 'Scope Configuration'

>> config = get_param ( [sablock],'Spectrum Analyzer Configuration');

Error at element 1 of first input to get_param:

block_diagram does not have a parameter named 'Spectrum Analyzer Configuration'

>> config = get_param ( [sablock],'dBm');

Error at element 1 of first input to get_param:

block_diagram does not have a parameter named 'dBm'

Interesting the sablock command returns a (1x7) array with numbers I dont recognise and why 7 values ?

I think I need to specify a Spectrum Analyzer Configuration object for the spectrum analyzer block, then use the

spectrumTable = getSpectrumData(scope) command to read the dBm trace ? As you can see from my attempts above I am having trouble specifying the sa configuration using the config and get_param commands/functions.

Any help would be most welcome.

Answer 1

[Fangjun Jiang]

Run this to open the document and example, I believe the answer can be found there. The key is probabaly the function getMeasurementsData()

web(fullfile(docroot, 'dsp/ref/dsp.spectrumanalyzer.getmeasurementsdata.html'))

or from https://www.mathworks.com/help/releases/R2019b/dsp/ref/dsp.spectrumanalyzer.getmeasurementsdata.html

[Derek Eccles]

Hi Fangjun, many thanks for you response.

Unfortunately, I am still not having much success :

>> sablock = fsk, '/Spectrum Analyzer' ;

sablock =

0

4

0

0

0

0

1

>> data = [];

>> data = [data;getMeasurementsData(sablock)];

Undefined function 'getMeasurementsData' for input arguments of type 'double'.

>> data = getMeasurementsData(sablock)

Undefined function 'getMeasurementsData' for input arguments of type 'double'.

>> data = [data;getMeasurementsData(sablock)];

Undefined function 'getMeasurementsData' for input arguments of type 'double'.

>> sablock = fsk, '/Spectrum Analyzer' ;

sablock =

0

4

0

0

0

0

1

>> cfg = get_param ( [sablock],'ScopeConfiguration');

Error at element 1 of first input to get_param:

block_diagram does not have a parameter named 'ScopeConfiguration'

>> cfg.CursorMeasurements.Enable = true;

cfg.ChannelMeasurements.Enable = true;

cfg.PeakFinder.Enable = true;

cfg.DistortionMeasurements.Enable = true;

>> data = getMeasurementsData(cfg)

Undefined function 'getMeasurementsData' for input arguments of type 'struct'.

>> Undefined function 'getMeasurementsData' ?

[Derek Eccles]

I did a search for undefined function and there seemed to be a lot of replies dealing with setting the correct path ?

I dont see how this would be applicable in my case ?

[Fangjun Jiang]

What are you trying to do with this? "sablock" is goint to have the same value as "fsk"

sablock = fsk, '/Spectrum Analyzer'

Open the html weblink, there is a model, there is a spectrum analyzer block, there are example code!

[Derek Eccles]

I have used a very simple model in simulink called fsk.slx to generate a baseband m=2 fsk signal.

I have also used Fourier Analysis to calculate the frequency response of such a signal and plotted it using EXCEL spreadsheet.

I was hoping to export the frequency response in simulink into EXCEL so I could compare the two responses.

[Fangjun Jiang]

Then, it should be sablock='fsk/Spectrum Analyzer'. Or, click (once) the Spectrum Analyzer block in your model, go to Command Window, type "sablock=gcb" and you'll get the full path of the Spectrum Analyzer block. Then follow the example in the webpage.

I don't know why your previous post shows some numerical numbers.

[Derek Eccles]

I have used the following MATLAB code :

>> scope = fsk, '/ Spectrum Analyzer ' ;

>> config = get_param (gcb, 'ScopeConfiguration');

>> specTable = getSpectrumData(config)

To get the following result :

specTable =

1×3 table

SimulationTime Spectrum FrequencyVector

______________ ______________ _______________

[2.0000e-05] [163×1 double] [163×1 double]

I dont really understand the code but it gets me what I want.

It would be nice to know why :

1. Only 3 parameters are returned.

2. The simulation time, spectrum and frequencyvector parameters were selected to be returned.

3. 163 samples were returned.

4. scope = fsk, '/ Spectrum Analyzer ' ; returns a 1x7 array of numbers, mostly zero.

[Fangjun Jiang]

They all depend on your simulation data and setting.

If your model name is 'fsk.slx', then specifying the full path of the scope block should be scope='fsk/Spectrum Analyzer'. type "fsk" before and after the simulation to see what happened. "fsk" should just bring up your model.

[Derek Eccles]

"They all depend on your simulation data and setting." - Is there something I can read to help me understand this ? For example I have stipulated 100 samples in my model but 163 are returned ?

Tried adding path in MATLAB with the following results ?

addpath('Derek/1electronics/1TELECOMMS/4MODULATION/1FSK/2-FSK MODULATOR/BASEBAND/NONCOHERENT')

Warning: Name is nonexistent or not a directory: C:\Derek\1electronics\1TELECOMMS\4MODULATION\1FSK\2-FSK

Modulator\BaseBand\NONCOHERENT\Derek\1electronics\1TELECOMMS\4MODULATION\1FSK\2-FSK

MODULATOR\BASEBAND\NONCOHERENT

> In path (line 109)

In addpath (line 86)

>> addpath('Derek/1electronics/1TELECOMMS/4MODULATION/1FSK/2-FSK MODULATOR/BASEBAND/NONCOHERENT'/fsk.slx')

Undefined variable "fsk" or class "fsk.slx".