Package ptolemy.math

Class SignalProcessing.RaisedCosineSampleGenerator

  • All Implemented Interfaces:
    DoubleUnaryOperation
    Enclosing class:
    SignalProcessing
    public static class SignalProcessing.RaisedCosineSampleGenerator
extends java.lang.Object
implements DoubleUnaryOperation
    This class generates samples of a raised cosine pulse, or if the excess is zero, a modified sinc function.

    The function that is computed is: 

             sin(PI t/T)   cos(excess PI t/T)
  h(t) = ----------- * -----------------
          PI t/T      1-(2 excess t/T)2

    This is called a "raised cosine pulse" because in the frequency domain its shape is that of a raised cosine.

    For some applications, you may wish to apply a window function to this impulse response, since it is rather abruptly terminated at the two \ ends.

    This implementation is ported from the Ptolemy 0.x implementation by Joe Buck, Brian Evans, and Edward A. Lee. Reference: E. A. Lee and D. G. Messerschmitt, Digital Communication, Second Edition, Kluwer Academic Publishers, Boston, 1994.

    • Constructor Summary

      Constructors 
      Constructor Description
      RaisedCosineSampleGenerator​(double firstZeroCrossing, double excess)
      Construct a RaisedCosineSampleGenerator.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      double operate​(double time)
      Return a sample of the raised cosine pulse, sampled at the specified time.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • RaisedCosineSampleGenerator

        public RaisedCosineSampleGenerator​(double firstZeroCrossing,
                                   double excess)
        Construct a RaisedCosineSampleGenerator.
        Parameters:
        firstZeroCrossing - The time of the first zero crossing, after time zero. This would be the symbol interval in a communications application of this pulse.
        excess - The excess bandwidth (in the range 0.0 to 1.0), also called the rolloff factor.

    • Method Detail

      • operate

        public final double operate​(double time)
        Return a sample of the raised cosine pulse, sampled at the specified time.
        Specified by:
        operate in interface DoubleUnaryOperation
        Parameters:
        time - The operand.
        Returns:
        The results of the operation.