Downsampling using MATLAB Simulink for an input signal

I am trying to downsample a signal of 20MHz to 1 MHz using Simulink. my targetted hardware is ZYNQ706 with AD9361 when do I downsample the signal I need to add buffer and unbuffer before and after downsampler but the problem is we cannot generate HDL code for these for that purpose we are using serializer and deserializer but using these blocks we have following issues

It slows down the bit file generation

It skips the low amplitude signals that might be due to low sample counts

How can I resolve the issue so I may be able to downsample the signal correctly and the generation of bit files speed is also not impacted. Is ther any other block with same purpose with HDL code generation

[Walter Roberson]

Can you use a Downsample block? https://www.mathworks.com/help/dsp/ref/downsample.html

[muhammad ahmad]

I am using Downsample block

[Walter Roberson]

https://www.mathworks.com/help/dsphdl/ref/dsphdl.firrateconverter-system-object.html is specifically for HDL

Answer 1

[Bharath Venkataraman]

You can use the Downsample block with Scalar input in DSP System Toolbox.

As Walter points out, you can also use the HDL Optimized blocks in DSP HDL Toolbox - these include FIR Decimator and the FIR Rate Converter blocks.