Preliminary testing

At this stage of the implementation, your processor should be correctly instantiated and recognised by the framework. In some cases (e.g., your processor is a simple single input / single output processor), it might even be correctly integrated and routed to other processors. In any case, now is a good time to take a break from writing code and do some preliminary testing. We will go through a few example tests you can run, describe which problems could arise and suggest how to solve them. Try to run these tests in the order they are listed below, as this will help troubleshooting. They should run as expected before you go further in your implementation.


You will not be able to instantiate your processor before you have written a concrete implementation to Processor abstract methods. To carry out the tests below, just write empty processChunk and reset methods. In this way, Matlab will not complain about trying to instantiate a class that contains abstract methods. The actual implementation of these methods will be described in later sections.

Default instantiation

As mentioned when implementing the constructor, you should be able to get a valid instance of your processor by calling its constructor without any input arguments:

>> p = myNewProcessor

If this line returns an error, then you have to revise your implementation of the constructor. The error message should indicate where the problem is located, so that you can easily correct it. If your processor cannot be instantiated with no arguments, then it will not be listed as a valid processor.

If on the other hand this line executed without error, then there are two things you should control:

  1. The line above (if not ended by a semicolon) should display the visible, public properties of the processor. Check that this list corresponds to the properties you defined in your implementation. The property values should be the default values you have defined in your getParameterInfo static method. If a property is missing, then you forgot to list it in the beginning of your class definition (or you defined it as Hidden or Private). If a value is incorrect, or empty, then it is a mistake in your getParameterInfo method. In addition, the Type property should refer to the name field returned by getProcessorInfo static method.
  2. Inspect the external parameters of the processor by typing p.parameters. This should return a list of all external parameters. Control that all parameters are there and that their default value is correct.

To test that your external properties are indeed dependent, you can change the value of one or more of them directly in your parameter processor property and see if that change is reflected in the dependent property. For example if you type:'xx_par1') = someRandomValue

then this should be reflected in the property associated with that parameter.


The input and output frequency properties of your processor, FsHzIn and FsHzOut are probably incorrect, but that is normal as you did not specify the sampling frequency when calling the constructor with no arguments.

Is it a valid processor?

To test whether your processor is recognised as a valid processor, run the requestList script. The signal request name corresponding to your processor should appear in the list (i.e., the name defined in getProcessorInfo.requestName). If not (and the previous test did work), then maybe your class definition file is not located in the correct folder. Move it to the src/Processors folder. Another possibility is that you made your processor hidden (which should not happen if you followed these instructions). Setting explicitly the bHidden property of your processor to 1 will hide it from the framework. This is used in order to allow “sub-processors” in the framework, but it is probably not the case for you here so you should not enable this option.

Are parameters correctly described?

If your processor is properly recognised, then you can call the parameterHelper script from the command window. There you should see a new category corresponding to your processor. Clicking on it will display a list of user-controllable parameters for your processor, as well as their descriptions. Feel free to adjust your getParameterInfo static method to have a more suitable description.