HOW TO GET DATA (imaginary) FROM FREQUENCY RANGES

Hello everybody I am trying to get data points from a trace. Each point (Y axis) corresponds to a different frequency (X axis). I know the number of points, and the start and end frequencies of each range. But there are two or more frequency ranges. The delta of frequency is different from one range to another. So

Does anyone know how to do it, please?

[Image Analyst]

What form is your input data in? A text file? An Excel workbook? Some picture printed in a paper journal? A CSV file? sagrario, you need to supply more info - we need something to go on if we are to help you. http://www.mathworks.com/matlabcentral/answers/728-how-do-i-write-a-good-question-for-matlab-answers

Answer 1

[Star Strider]

If you need to read data from an Excel spreadsheet, use the xlsread function. As for plotting them, see the documentation for the fft function (even if the data you have is already in the frequency domain, the plot documentation there will be helpful).

Answer 2

[sagrario dominguez]

My complex data are the result of the measurements done with the Vector Network Analyzer 4395A: any of the scattering parametters which characterize one device. The Vector Network Analyzer 4395A works (in my case) in the "SWEEP LIST MODE", that is, there may be several frequency ranges, and several frequency points at each range. The attached table could be the display of one of my setups.

Here segment is either of the frequency ranges. START, STOP are the start and stop measurements frequencies, POINT is the nubmer of points at each range. And POWE and BW are the power and bandwith used for measuring

I can get the list of my data on the instrument display/screen, via MATLAB. But I can't manage to get these values in the command window.

Thanks for the suggestion, although I do not know yet how to use fft fft function in this case

[Star Strider]

There is essentially nothing in that file. The ‘raw’ output (the third output of xlsread) is:

[d,s,r] = xlsread('sagrario dominguez DISPLAY.xls');

r = 

    Columns 1 through 5

      'Possible display …'     [         NaN]    [       NaN]    [         NaN]    [  NaN]
      [                NaN]    [         NaN]    [       NaN]    [         NaN]    [  NaN]
      'segment  '              'START '          'STOP'          ' POIN   '        'POWER'
      [                NaN]    [         NaN]    [       NaN]    [         NaN]    [  NaN]
      [        1.0000e+000]    '100 KHz     '    ' 1MHz     '    [10.0000e+000]    '0dBm' 
      [        2.0000e+000]    '2 MHz'           '20MHz'         [10.0000e+000]    '0dBm' 

    Column 6

      [  NaN]
      [  NaN]
      'IFBW '
      [  NaN]
      '10Hz' 
      '10Hz'

Answer 3

[sagrario dominguez]

I am also making use of the programming manual of the VNA 4395A network analyzer