Unable to run Simulink simulation

I used FilterDesigner to create a banpass filter. I have imported it in Simulink and connected to a chirp block and a spectrum analyzer.

I have quantized the filter inputs and outputs. When I try to simulate, I get the following error:

Expected a GP/Channel-In block to be connected to an input pin in [bandpass3_bandpass3], but instead found block ["Input Quantizer"].

Answer 1

[Simar]

Hi Costas Hatzinikolaou,

The error message you are encountering suggests that there is a specific expectation for the type of block that should be connected to the input of bandpass filter within Simulink, which in this case, is not being met due to the presence of an "Input Quantizer" block. This issue can arise from several factors related to how filter expects its inputs to be formatted or handled, especially after importing from FilterDesigner. Below are some steps to troubleshoot and potentially resolve this issue:

1. Review Filter Configuration: Check with settings or parameters that specify expected input signal type. If filter is configured to expect a specific type of input not compatible with the "Input Quantizer", this could be the source of the issue.

2. Check Documentation: Refer the documentation for "Input Quantizer" block to understand their requirements and capabilities better. There are notes and examples on how to properly interface quantized signals with specific types of filter blocks.

• Input Quantizer- https://www.mathworks.com/help/simulink/slref/quantizer.html?searchHighlight=input%20quantizer%20block&s_tid=srchtitle_support_results_1_input%20quantizer%20block

3.Signal Conversion: If filter expects a different type of input (e.g., floating-point instead of fixed-point), consider using signal conversion block between the "Input Quantizer" and the filter. Simulink provides blocks like DataTypeConversion that can be used to convert between different data types and formats.

• Signal Conversion- https://www.mathworks.com/help/simulink/slref/signalconversion.html?searchHighlight=signal%20conversion%20block&s_tid=srchtitle_support_results_1_signal%20conversion%20block
• DataTypeConversion- https://www.mathworks.com/help/simulink/slref/datatypeconversion.html?searchHighlight=data%20type%20conversion&s_tid=srchtitle_support_results_1_data%20type%20conversion

4. Bypass Quantizer for Testing: As a diagnostic step, temporarily bypass the "Input Quantizer" and connect signal directly to the filter's input. If the simulation runs successfully without the quantizer, the issue is related to how the quantized signal is being handled or expected by the filter.

5. Consult Simulink Examples: Look for examples or demos within Simulink that involve similar configurations (quantized inputs to filters). It would provide insights into proper block configurations and connections. Within examples, type “filter” to perform scoped search.

The key is to ensure compatibility between the signal format output by the "Input Quantizer" and the expectations of the filter block imported from FilterDesigner.

Hope it helps!

Best Regards,

Simar