FIR filtering

Discussion in 'Python' started by LabWINC, Mar 15, 2006.

  1. LabWINC

    LabWINC Guest

    Hi all,
    i'm looking for a module to implement a digital FIR filter!
    Can anyone help me?

    Thanks,

    Vincent
     
    LabWINC, Mar 15, 2006
    #1
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  2. LabWINC

    Peter Hansen Guest

    LabWINC wrote:
    > i'm looking for a module to implement a digital FIR filter!
    > Can anyone help me?


    Is this for homework, for academic interest, for a control system
    problem, or what? Some context would be useful in helping us answer.

    (The first thing that occurs to me, for example, is "why don't you just
    write it yourself? ...it's not like they're a complicated equation and
    if you have the coefficients, you practically have the code already."
    But that might not be the best approach if this is a real-world situation.)

    -Peter
     
    Peter Hansen, Mar 15, 2006
    #2
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  3. LabWINC

    LabWINC Guest

    It's for research work. I'm implementing an algorithm from a matlab
    one.
    It could be very difficult to find the fir coefficients because i have
    lot of fileters to implement.

    Vincent
     
    LabWINC, Mar 15, 2006
    #3
  4. LabWINC wrote:
    > Hi all,
    > i'm looking for a module to implement a digital FIR filter!
    > Can anyone help me?
    >
    > Thanks,
    >
    > Vincent
    >

    gnuradio?

    Hans Georg
     
    Hans Georg Krauthaeuser, Mar 15, 2006
    #4
  5. LabWINC

    LabWINC Guest

    What's gnuradio?
     
    LabWINC, Mar 15, 2006
    #5
  6. Hans Georg Krauthaeuser, Mar 15, 2006
    #6
  7. LabWINC wrote:

    > What's gnuradio?


    Google dead again? Boy, must be one of these days...

    Diez
     
    Diez B. Roggisch, Mar 15, 2006
    #7
  8. LabWINC

    LabWINC Guest

    I can't understand how gnuradio can help me...
    I find scipy is the only way to implement a good FIR.

    Thanks,

    Vincent
     
    LabWINC, Mar 15, 2006
    #8
  9. LabWINC

    John Hunter Guest

    >>>>> "LabWINC" == LabWINC <> writes:

    LabWINC> Hi all, i'm looking for a module to implement a digital
    LabWINC> FIR filter! Can anyone help me?

    scipy.org

    Between scipy and matplotlib, you'll feel quite comfortable with
    python as a former matlab user

    help scipy.filter (see FIR filter design below)

    DESCRIPTION
    Signal Processing Tools
    =======================

    Convolution:

    convolve -- N-dimensional convolution.
    correlate -- N-dimensional correlation.
    fftconvolve -- N-dimensional convolution using the FFT.
    convolve2d -- 2-dimensional convolution (more options).
    correlate2d -- 2-dimensional correlation (more options).
    sepfir2d -- Convolve with a 2-D separable FIR filter.


    B-splines:

    bspline -- B-spline basis function of order n.
    gauss_spline -- Gaussian approximation to the B-spline basis
    function.
    cspline1d -- Coefficients for 1-D cubic (3rd order)
    B-spline.
    qspline1d -- Coefficients for 1-D quadratic (2nd order)
    B-spline.
    cspline2d -- Coefficients for 2-D cubic (3rd order)
    B-spline.
    qspline2d -- Coefficients for 2-D quadratic (2nd order)
    B-spline.

    Filtering:

    order_filter -- N-dimensional order filter.
    medfilt -- N-dimensional median filter.
    medfilt2 -- 2-dimensional median filter (faster).
    wiener -- N-dimensional wiener filter.

    symiirorder1 -- 2nd-order IIR filter (cascade of first-order
    systems).
    symiirorder2 -- 4th-order IIR filter (cascade of
    second-order systems).
    lfilter -- 1-dimensional FIR and IIR digital linear
    filtering.

    deconvolve -- 1-d deconvolution using lfilter.

    hilbert --- Compute the analytic signal of a 1-d signal.
    get_window --- Create FIR window.

    detrend --- Remove linear and/or constant trends from
    data.


    Filter design:

    remez -- Optimal FIR filter design.
    firwin --- Windowed FIR filter design.
    iirdesign --- IIR filter design given bands and gains
    iirfilter --- IIR filter design given order and critical
    frequencies
    freqs --- Analog filter frequency response
    freqz --- Digital filter frequency response

    Matlab-style IIR filter design:

    butter (buttord) -- Butterworth
    cheby1 (cheb1ord) -- Chebyshev Type I
    cheby2 (cheb2ord) -- Chebyshev Type II
    ellip (ellipord) -- Elliptic (Cauer)
    bessel -- Bessel (no order selection available --
    try butterod)

    Linear Systems:

    lti -- linear time invariant system object.
    lsim -- continuous-time simulation of output to linear system.
    impulse -- impulse response of linear, time-invariant (LTI)
    system.
    step -- step response of continous-time LTI system.

    LTI Reresentations:

    tf2zpk -- transfer function to zero-pole-gain.
    zpk2tf -- zero-pole-gain to transfer function.
    tf2ss -- transfer function to state-space.
    ss2tf -- state-pace to transfer function.
    zpk2ss -- zero-pole-gain to state-space.
    ss2zpk -- state-space to pole-zero-gain.

    Waveforms:

    sawtooth -- Periodic sawtooth
    square -- Square wave
    gausspulse -- Gaussian modulated sinusoid
    chirp -- Frequency swept cosine signal

    Wavelets:

    daub -- return low-pass filter for daubechies wavelets
    qmf -- return quadrature mirror filter from low-pass
    cascade -- compute scaling function and wavelet from
    coefficients
     
    John Hunter, Mar 15, 2006
    #9
  10. LabWINC wrote:
    > I can't understand how gnuradio can help me...
    > I find scipy is the only way to implement a good FIR.


    Well, then do it with scipy...
    gnuradio has a module for FIR. I never used it. I just wanted to share
    that information.

    Hans Georg
     
    Hans Georg Krauthaeuser, Mar 15, 2006
    #10
  11. LabWINC

    LabWINC Guest

    Thank you too Georg
     
    LabWINC, Mar 15, 2006
    #11
  12. LabWINC

    Peter Hansen Guest

    LabWINC wrote:
    > It's for research work. I'm implementing an algorithm from a matlab
    > one.
    > It could be very difficult to find the fir coefficients because i have
    > lot of fileters to implement.


    Oh, you mean you need to find the coefficients, not just implement the
    FIR filter itself. (Perhaps to some these describe the same thing, but
    I would call the former "designing the filter".)

    I see John Hunter's post shows scipy probably has what you need.

    -Peter
     
    Peter Hansen, Mar 15, 2006
    #12
  13. LabWINC

    LabWINC Guest

    I'm interested in finding coefficient and implementig the filter as
    well.
    John's post is what i need.

    John Hunter wrote:
    > help scipy.filter (see FIR filter design below)


    How can i get the help like yours?

    If i type help scipy.filter it give me an error

    help scipy.filter
    File "<input>", line 1
    help scipy.filter
    ^
    SyntaxError: invalid syntax



    I'm sorry but i'm new of python,

    Vincent
     
    LabWINC, Mar 15, 2006
    #13
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