More noise with highpass filter

Hi,

ADSP-21489

I'm using the IIR hardware accelerator of the DSP with it's own example program provided by analog devices.

I have implemented a 6th order IIR low and highpass filter with cutoff frequency 800 Hz. As shown in the pictures, the noisefloow with the highpass filter is much higher than the one with the lowpass filter. Has anyone got an idea where that might come from?

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  • 0
    •  Analog Employees 
    on Mar 27, 2019 8:24 AM

    Hi,

    It seems you are using ADSP-21489. Do you see this problem on EZ-Kit ? BTW, can you let me know how you are generating the filter coefficients. Are you using any filter coefficient generating tool like MATLAB or GNU Octave? Is it possible for you to check whether the coefficients you have provided yields the same result on any other tool(like MATLAB etc.)?Are you using VDSP or CCES?
    Did you observe noise when changing the cutoff frequency or with any other order filter?

    Regards,
    Lalitha S

Reply
  • 0
    •  Analog Employees 
    on Mar 27, 2019 8:24 AM

    Hi,

    It seems you are using ADSP-21489. Do you see this problem on EZ-Kit ? BTW, can you let me know how you are generating the filter coefficients. Are you using any filter coefficient generating tool like MATLAB or GNU Octave? Is it possible for you to check whether the coefficients you have provided yields the same result on any other tool(like MATLAB etc.)?Are you using VDSP or CCES?
    Did you observe noise when changing the cutoff frequency or with any other order filter?

    Regards,
    Lalitha S

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