To determine the quantization and modeling effects on a filtering process, not only the analyzation of the frequency response of a fixed-point filter is required, but also the simulation of the filtering process with the actual data.

You can use the DFD FXP MRate Simulation VI to simulate the filtering process. To verify if the fixed-point multirate filter works as you expect, compare the simulation result with the actual filtering result that you obtain by processing the same signal with the reference floating-point multirate filter. Ensure that the simulation result matches the actual filtering result. If the simulation result does not match the actual floating-point filtering result, try making the following adjustments:

  • Return to the quantization step. Modify the word length for the filter coefficients and the scale type to avoid overflow or underflow.
  • Adjust the specifications and redesign the floating-point multirate filter.