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Users Manual for Program PSD   

Table of Contents

Introduction

Program PSD calculates the power spectral density of a time-domain variable and writes the result on file UTFIL.

Internal calculation procedure

Program PSD reads data from INFIL, the PSD-spectra is generated by Fourier transformation of the auto-correlation spectra. The spectra will pass a Hanning window in order to make the spectra smoother.

Input data commands

Input data are read in free format, valid separators between the input values are <space>, <comma>, <tab>, <equal sign> or <carriage return>. The commands can be written both in lower and upper case letters. The operation of the program is controlled by the commands described below; some of the commands also need arguments.

NOTE

Commentary line.
Declared = Character*80    Default = Blank

FORMF

Format in which file UTFIL shall be written.
The string should be written in FORTRAN, and shall be enclosed in parenthesis.
Declared = Character*80    Default = '(1PE15.6, 5X, E15.6)'

FORMIN

Format in which file INFIL shall be read.
The string should be enclosed in parenthesis e.g. '(E15.6, 5X, E15.6)'. The format specification shall be written in a way that it will fit into the FORTRAN read statement. The format specification given in the example above makes program PSD to read the first 15 characters in file INFIL into the X-variable, the next 5 characters will be skipped, the next 15 characters will be read into the Y-variable.
If FORMIN is given the value 'SNGL', file INFIL will be read in free format.
Declared Character*80    Default = SNGL

INFIL

File containing the input data curve.
File INFIL consists of value-pair Xvar and Yvar. The file is read according to the format given in FORMIN. Lines starting with the #-sign are considered as being commentary lines.
Declared = Character*80    Default = Blank

UTFIL

Name of output data file.
The file is written according to the format given in FORMF. Declared = Character*80    Default = Blank

XMOVE

Amount of displacement when calculating the auto-correlation.
A large XMOVE gives a better accuracy but longer execution time. XMOVE cannot be bigger than the length of the curve in INFIL multiplied by two.
Declared Real*4    Default = 300 [m]

XSTART

Starting coordinate when reading INFIL.
Declared = Real*4    Default = 0. [m]

XSTOP

End coordinate when reading INFIL.
Declared = Real*4    Default = 1.E20 [m]

EOF

Command which terminates further input data reading.

Example:

Following example: Master.misc_psdf can be used as a master file:

                                               
 ##                                            
 ##        Input data for program PSD          
 ##                                            
  XMOVE= 150  XSTART= 0  XSTOP= 1.E20          
                                               
  FORMIN= SNGL                                 
  INFIL = ucat/cos_l5d2.sngl                   
                                               
  FORMF= '(1PE15.6,5X,E15.6)'                  
  UTFIL= ucat/cos_l5d2.psd