Package builder.resid.residfp

Klasse ExternalFilter

java.lang.Object
builder.resid.residfp.ExternalFilter
final class ExternalFilter extends Object
The audio output stage in a Commodore 64 consists of two STC networks, a low-pass filter with 3-dB frequency 16kHz followed by a high-pass filter with 3-dB frequency 16Hz (the latter provided an audio equipment input impedance of 1kOhm).

The STC networks are connected with a BJT supposedly meant to act as a unity gain buffer, which is not really how it works. A more elaborate model would include the BJT; however, DC circuit analysis yields BJT base-emitter and emitter-base impedances low enough to produce additional low-pass and high-pass 3dB-frequencies in the order of hundreds of kHz. This calls for a sampling frequency of several MHz, which is far too high for practical use.

Autor:
Ken Händel

  • Feldübersicht

    Felder
    Modifizierer und Typ
    Feld
    Beschreibung
    private static final double
    LOWPASS_FREQUENCY
     
    private float
    Vhp
    highpass
    private float
    Vlp
    lowpass
    private float
    w0hp
    Cutoff frequencies.
    private float
    w0lp
    Cutoff frequencies.

  • Konstruktorübersicht

    Konstruktoren
    Konstruktor
    Beschreibung
    ExternalFilter()
    Constructor.

  • Methodenübersicht

    Modifizierer und Typ
    Methode
    Beschreibung
    (Package privat) float
    clock(float Vi)
    SID clocking - 1 cycle.
    (Package privat) void
    reset()
    SID reset.
    (Package privat) void
    setClockFrequency(double frequency)
    Setup of the external filter sampling parameters.
    (Package privat) void
    zeroDenormals()
     

    Von Klasse geerbte Methoden java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Felddetails

    • LOWPASS_FREQUENCY

      private static final double LOWPASS_FREQUENCY
      Siehe auch:

    • Vlp

      private float Vlp
      lowpass

    • Vhp

      private float Vhp
      highpass

    • w0lp

      private float w0lp
      Cutoff frequencies.

    • w0hp

      private float w0hp
      Cutoff frequencies.

  • Konstruktordetails

    • ExternalFilter

      ExternalFilter()
      Constructor.

  • Methodendetails

    • clock

      float clock(float Vi)
      SID clocking - 1 cycle.
      Parameter:
      Vi - vi

    • zeroDenormals

      void zeroDenormals()

    • setClockFrequency

      void setClockFrequency(double frequency)
      Setup of the external filter sampling parameters.
      Parameter:
      frequency - clock frequency

    • reset

      void reset()
      SID reset.