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Harmonic Notch filter

Discussion in 'Electronic Design' started by Stretto, May 11, 2011.

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  1. Stretto

    Stretto Guest

    Is it possible to design a notch like filter that not only filters a
    frequency but all it's harmonics? The point here is to design a circuit not
    much more complicated than a normal notch filter and not n independent notch
    filters, one for each harmonic.
     
  2. Phil Allison

    Phil Allison Guest

    "Stretto" <>

    ** Why don't you just **** off ?

    All you are doing is wasting our time with your bullshit and mindless
    TROLLING !!

    ** Yes.

    ** Not possible.




    ..... Phil
     
  3. Phil Allison

    Phil Allison Guest

    "Stretto"

    ** They are nothing like simple.


    ** Piss OFF you FUCKING TROLL !!!!!!!!!!!!!!


    ** That was not your question.

    You TROLLING PIG
     
  4. Stretto

    Stretto Guest

    "John Walliker" wrote in message

    Look up "comb filter". They can be quite simple and are widely used.
    However, filtering "all" the harmonics is not a realistic goal. Also,
    there are problems with some potential applications. For example,
    many people have attempted to filter out mains interference and its
    harmonics from audio recordings with comb filters, but the results are
    often disappointing.
    Other problems are that if the fundamental frequency varies slightly
    the change is magnified in the higher harmonics and they may miss the
    filter notches unless a tracking filter is used. The passbands are
    not flat in the simple implementations and the phase response is
    "interesting".
    -----

    Thanks, this was basically what I was interested in. The mains frequency is
    rather tightly controlled so why is it so difficult to filter out? 60hz is
    not a musical tone(inbetween A# and B) and one has about a hz or two to play
    with.
     
  5. Rich Grise

    Rich Grise Guest

    Probably because from about 100 Hz up to probably over a KHx (Google
    Minnie Riperton) are in the range of the fundamental of the human voice.
    300 Hz - 3 KHz has enough harmonics for an intelligible voice, but can
    sound "tinny". That's the BW in original telephone spec, and was VERY
    common in the days when I was hanging around with HAMs.

    Cheers!
    Rich
     
  6. Rich Grise

    Rich Grise Guest

    It's not difficult to filter out in general, it's difficult to filter it
    and its harmonics out of a hi-fi audio signal without making the audio sound
    weird.

    Hope This Helps!
    Rich
     
  7. Rich Grise

    Rich Grise Guest

    Uh-oh, Phil's having another episode.
     
  8. Phil Allison

    Phil Allison Guest

    "Rich Grise"
     
  9. Phil Allison

    Phil Allison Guest

    "Bill Sloman"

    The mains frequency is only tightly controlled in the long term -


    ** Wrong.




    ..... Phil
     
  10. Phil Allison

    Phil Allison Guest

    Is it possible to design an apostrophe that automatically knows when
    it's not needed?


    ** The comma above knew when it ws needed.


    ..... Phil
     
  11. Stretto

    Stretto Guest

    wrote in message

    Is it possible to design an apostrophe that automatically knows when
    it's not needed?
     
  12. Martin Brown

    Martin Brown Guest

    Depends what you mean by tightly controlled. The frequency shifts
    measureably when for example at half time on cup final day everyone in
    the country switches on a 3kW kettle more or less simultaneously.

    It is extremely tightly controlled over 24 hours and longer term for
    obvious reasons. But it is generally slower at times of peak daytime
    load and runs fast late at night to catch up. In the old days of
    synchronous mains drives on telescopes this used to annoy astronomers.

    Regards,
    Martin Brown
     
  13. Phil Allison

    Phil Allison Guest

    Okay. This tells us that you wish to be thought omniscient.


    ** Nope.

    It asks you to prove your pig ignorant, fuckwit assertion.

    And that proof must be in the context of a typical ANALOGUE notch filter at
    50 / 60 Hz.

    Quote form the OP:

    " The point here is to design a circuit not much more complicated than a
    normal notch filter. "

    Say +/- 1% of the centre frequency over the 0C to 50C temp range.

    To be very generous.

    You have no hope - **** head.



    .... Phil
     
  14. Phil Allison

    Phil Allison Guest

    "Stretto"


    ** Why don't you " **** OFF ''

    you TROLLING WOG PIG ???
     
  15. Twenty seconds of googling brought up this:
    <http://leapsecond.com/pages/mains/>

    Jeroen Belleman
     
  16. Phil Allison

    Phil Allison Guest

    Okay. This tells us that you wish to be thought omniscient.

    ** Nope.

    It asks you to prove your pig ignorant, fuckwit assertion.

    And that proof must be in the context of a typical ANALOGUE notch filter at
    50 / 60 Hz.

    Quote form the OP:

    " The point here is to design a circuit not much more complicated than a
    normal notch filter. "

    Say +/- 1% of the centre frequency over the 0C to 50C temp range.

    To be very generous.

    You have no hope - **** head.



    .... Phil
     
  17. Phil Allison

    Phil Allison Guest

    "Bill Sloman"
    "Phil Allison"

    You asked me to prove my assertion - which I did,


    ** You links proved the exact opposite !!!!!!!!!!!!!!

    " The frequency has so far rarely deviated more than 0.2 % from 50 Hz, i.e.
    it was almost always between 49.9 and 50.1 Hz. "


    - rather than arguing with any of the points I went to the trouble
    of making you, just re-assert your original - ill-founded - claims and
    throw in the extra additional - equally ill-founded - claim that I'm
    lying.

    ** Course you are lying.

    You tell lie after lie after lie.

    Deliberately posting wrong and refusing to ever back down IS LYING.


    ..... Phil
     
  18. Martin Brown

    Martin Brown Guest

    Astronomers have a *lot* more brains than you do!

    Modern scopes are mostly servo controlled with shaft encoder feedback
    under computer control these days - true even for high end amateur
    scopes. This allows them to automatically slew to targets, correct for
    the change in apparent motion with altitude and accept autoguiders.

    Industrial stepper drives were used for a while in the late 70's, but
    tended to cause unwanted structural vibration even with microstepping
    compared to old synchronous clock motors driven from a sine wave.

    But for a very long time cheap and ubiquitous synchronous clock motors
    were the way to drive telescopes. A few customers even had Rolls Royce
    cut large 359 tooth gears for the main drive so that their scope would
    keep almost perfect sidereal time if the mains frequency was at exactly
    50Hz. They were the ones that were most miffed about the higher and
    variable mains frequency at night. This included an optical telescope by
    Grubb Parsons that at one time in the 1960's was at Jodrell Bank.

    It was definitely a step up from the governed clockwork drives that
    preceded them and were very sensitive to balance and temperature.

    Regards,
    Martin Brown
     
  19. Rich Grise

    Rich Grise Guest

    I once saw a telescope drive made from a clock movement, for some
    reason, the balance wheel was exposed, so you could see it going
    tick-tock...

    Cheers!
    Rich
     
  20. Nico Coesel

    Nico Coesel Guest

    I think you are seeing the drift of the crystal which drives the DDS.
    I once made a 0.5ppm DPLL to track public E1 clocks. Just blowing some
    air at the board caused the frequency to change because of the
    temperature change.
     
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