edit communication system parameters from commqpsktxrx ready example

i want to use different symbol rate that the deafult one. i want to chose 2400 symbol rate. but when i change it, i get this error "The MaximumFrequencyOffset property must be less than the SampleRate property divided by the modulation order. The error occurred for MATLAB System block ". however when i try to change this paramter, it does not change in the frequency compensator block.

Answer 1

[Vaibhav]

Hi Asmaa

I understand that you are facing issues when trying to modify the “symbol rate” and "MaximumFrequencyOffset" parameters in the Coarse Frequency Compensator block.

In this scenario, using a symbol rate of 2400 and assuming a default modulation order of 4 (like QPSK), the "MaximumFrequencyOffset" exceeds the permissible limit., which is calculated as the "SampleRate" divided by 4. This breaks the block's design rules.

To resolve this issue, possible workaround can be to adjust the "MaximumFrequencyOffset" to be less than "SampleRate / ModulationOrder". This ensures the frequency offset remains within the bandwidth defined by the symbol rate and modulation.

You can refer to the following MathWorks documentation for more information about "Coarse Frequency Compensator":

https://www.mathworks.com/help/comm/ref/coarsefrequencycompensator.html

Hope this helps!