IIR EMA MMA : what is th parameter?

zachliangzachliang
edited June 2019 in Problems and Issues
I dont know on where to put my questions , so decided to add that in this thread for discussion. I apologize if it is located in bad thread:
  • IIR Infinite Impulse Response (filter instead of smoothing algorithm afaik )
  • MMA Modified Moving Average
  • EMA Exponential Moving Average

The only I dont know is how this weighting parameter is defined in these 3 methods.
Any ideas ?
73s and TIA !

Comments

  • G8JNJG8JNJ
    Hi,

    There was a post on the subject some time ago, which may help a bit.

    http://forum.kiwisdr.com/discussion/comment/6604#Comment_6604

    This part is the most informative.

    "v1.279 has improved spectrum filter options. In addition to the default IIR filter you can now select an MMA (modified moving average) and EMA (exponential moving average) filter or no filtering at all. There is also a new slider for the parameter associated with each filtering algorithm:

    IIR: param = gain coefficient 0..1 (slower..faster)
    MMA: param = averaging size in samples (1..64)
    EMA: param = decay period (averaging size) in samples (1..64)

    The URL parameter options sp= and spp= allow the filter and filter parameter to be preset in the URL. See http://kiwisdr.com/quickstart/index.html#id-user-tune

    I implemented a minimum decay rate for the IIR filter. For various reasons the filtering is implemented after the waterfall colormap scaling. And with a more restricted colormap range (i.e. WF min slider less negative so no-signal waterfall area is black) the IIR filter would not decay for small signals as was observed.

    There is also a new "GND" momentary button (i.e. click/touch and hold). This zeros (grounds) the waterfall/spectrum input data so you can see how the various spectrum filters decay under no-signal conditions."

    Regards,

    Martin - G8JNJ
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