Simulink tapped delay block with vector inputs

All,

I have often needed a "shift-register" function in Simulink that can accept vector inputs. The tapped delay only supports scalar inputs. I typically build this function using the "Matlab Function" block.

How do other people solve this problem? Is there a built-in solution I am not aware of?

Maybe someone from MathWorks is reading these questions? It is a pretty big gap that there is no built-in way to build a shift register with vectors.

Thanks.

Answer 1

[Vanita]

Hi Sean,

To build a shift register block with vector input in Simulink, the Delay Line block from the DSP System Toolbox is a good option. This block supports vector inputs and can implement a shift register by delaying the input signal by a set number of samples. You can refer to the following document for more details:

https://www.mathworks.com/help/dsp/ref/delayline.html

Hope this helps!

[Sean]

I was unaware that the Delay Line block might work. I am not in a position to test it, but I appreciate the information. Thanks!

Answer 2

[praguna manvi]

Hi @Sean,

The "Tapped Delay" block natively accepts only scalar inputs. A workaround to pass vector inputs is to use a "Buffer" block, setting the "Overlap" property to one less than the buffer size. Here is a useful discussion thread on a similar use case:

https://www.mathworks.com/matlabcentral/answers/306046-tapped-delay-with-array-input

For more information on the "Buffer" block, refer to the following link:

https://www.mathworks.com/help/dsp/ref/buffer.html

[Sean]

Thanks for the response.

There are two problems with using the buffer block:

1. The sample rate changes. This isn't always what you want.
2. This block is not compatible with some of the codegen tools (the HDL coder, for example).