I/Q modulator

Hello,

Is there a way to drive the I/Q modulator tool in the RF blockset with an I/Q data file instead of a sinewave?

thansk,

Answer 1

[Umar]

Hi Dov,

In Simulink's RF Blockset, the I/Q modulator tool typically accepts sinewaves as inputs for modulation. However, there is a way to drive the I/Q modulator tool with an I/Q data file instead of a sinewave. This approach allows for more flexibility and the ability to use pre-recorded or generated I/Q data for modulation.

To achieve this, you can follow these steps:

Prepare the I/Q Data File: Create or obtain the I/Q data file that you want to use for modulation. The file should contain the In-phase (I) and Quadrature (Q) components of the signal.

Read the I/Q Data File: Use appropriate blocks in Simulink to read the I/Q data file. You can use the "From File" block to read the data from a file and feed it into the I/Q modulator.

Connect the I/Q Data to the I/Q Modulator: Connect the I/Q data obtained from the file to the input of the I/Q modulator tool in the RF Blockset. This will replace the sinewave input with the I/Q data for modulation.

Here is a simple example in Simulink demonstrating how to drive the I/Q modulator tool with an I/Q data file:

% Create a From File block to read the I/Q data file
iq_data = dsp.SignalSource('Signal', 'IQ_Data.mat', 'SamplesPerFrame', 1);
% Connect the I/Q data to the I/Q modulator
iq_modulator = comm.IQModulator;
modulated_signal = iq_modulator(iq_data());

By following these steps and adapting the example code to your specific requirements and file format, you can effectively drive the I/Q modulator tool in the RF Blockset with an I/Q data file. This method offers versatility and the ability to work with various types of signals beyond sinewaves.

Please let me know if you have further questions.

[Dov]

thank you Umar,

[Umar]

No problem, Dov. Glad to help out. Please let me know if you have further questions.

[Walter Roberson]

Note that if you use a From File block, then the file needs to be in timeseries format, or else needs to be a rectangular array in which the first column is time information.

There is no provision in Simulink From File for just loading blocks of data with implicit time step.

[Dov]

I have a .mat file that I converted from a sigmf data file, is there a way to convert it to timeseries rectangular form? thanks

[Umar]

Hi Dov,

Use MATLAB's built-in functions such as "load" to read the .mat file and then manipulate the data into a timeseries format.

For more information regarding this function, please refer to https://www.mathworks.com/help/matlab/ref/load.html

Additionally, consider exploring specific signal processing or time series analysis libraries that may offer direct support for converting sigmf data files into timeseries format. It's important to note that the exact approach may vary based on the specific structure and content of your .mat file and sigmf data.

If you have further details about the nature of your data, such as its dimensions, variables, or any specific requirements for the timeseries format, I can provide more tailored guidance.

[Walter Roberson]

TimeInterval = 0.01;  %change as appropriate. Should be same as 1/sampling_frequency
DataArray = as appropriate. Each row corresponds to a different time
TimeVector = (0:size(DataArray,1)-1) * TimeInterval;
TS = timeseries(DataArray, TimeVector);

[Dov]

thanks Walter,