ptolemy.math

Class SignalProcessing.RaisedCosineSampleGenerator

java.lang.Object

ptolemy.math.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 and Description
RaisedCosineSampleGenerator(double firstZeroCrossing, double excess) Construct a RaisedCosineSampleGenerator.

Method Summary

Modifier and Type	Method and 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.