Digital Down Converter: # Samples must be Integer multiple of decimation factor
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Hello,
I'm trying to simulate a system that receives an analog signal, samples it and performs various filtration and decimation tasks on the input. Essensially it is supposed to mimic a Zynq UltraScale+ operation.
The current system blocks look like this:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1653426/image.png)
The model is set at a fixed step size of 250 ps (4 GSa/s). A sinusoidal signal at a frequency of 503.75 MHz enters an RF front end, which adds amplification and noise. This signal is sampled by an ideal 14-bit ADC. It then enters a FIR decimator - up to this point everything works correctly.
Now instead of the FIR decimator I want to put a digital down converter, to convert from 503.75 MHz to 3.75 MHz, and apply a FIR decimator. All in one DDC block.
However, the DDC doesn't want to run. Whatever I do, it outputs the following error:
The number of rows in the input signal must be an integer multiple of the total decimation factor: 40.
I have added an output to workspace which clearly shows that the time vector is 4000 samples long. It is a multiple of 40.
I have tried changing the decimation factor to anything between 2 and 20, but nothing works. What am I missing?
The parameters of the DDC block are as follows (I have tried specifiying the input sample rate at 4 GHz - doesn't help):
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1653431/image.png)
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Answers (1)
Tom Richter
on 3 Apr 2024
Hi Egor,
I agree with Fangjun and suggest contacting Technical Support to help you with this issue/question. If you go to https://www.mathworks.com/support/contact_us.html, you can submit a support request and add example or reproduction files. The page also displays phone contact information based on your location.
Best regards,
Tom
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