The software developed to be used on an IBM PC, is contained in the archive sat.zip, produced using the PKZIP shareware package. The files contained within the archive are:
gnuplot.exe
To use the programs contained within, extract the files, and create a \tmp directory
for the program to write temporary files to. The program is then run using the
following syntax.
plo.bat
satplt.bat
satplt.gnu
setupdat.exe
satplt [filename] eg. satplt qp28036.sld
Having done this, the program will prompt the user for a series of options. It is worth noting that the files will be approximately 1320 seconds long and that by removing time marks and filtering the data, it is much easier to observe scintillation activity. A transcript for an example session is shown below.
satplt 14180406.qld Thu Apr 18 14:30:36 1996 UNIVQLD Sampling rate: 70.000000 per second Enter the range of times to plot (start and end) Times (in seconds): 100 1000 Sample interval (in record numbers): 20 Remove Marks and Filter Data (y or n)? yHaving followed these steps, the program will then send an output to screen that should look much like the example shown below.
As an alternative to the use of 'homegrown' software, the group has recently become aware of the the commercial data analysis package IDL. The possible use of this package to analyse the data recorded by the group is outlined below.
SCINTILLATION DATA ANALYSIS (ALTERNATIVE TO THE UNIX SATDAN
SOFTWARE) USING INTERACTIVE DATA LANGUAGE (IDL)
1. Requirements: IDL commercial software available from:
Research System Inc.,
777 29th Street,Suite 302,
Boulder,Co 80303,USA
Fax. 303 786-9909
2. Version 3.0 or higher
2. Computer requirements:
a. Minimum PC386, with 4 Mb RAM (a math cooprocessor advised)
b. PC486 (recommended) for higher versions
c. Window 3.1 required, run in the enhanced mode
3. The IDL allows to perform a multiple task of the standards
scintillation analysis as obtained from the Mark 1
(Brisbane,Australia) and Mark 2 (Kokobunji,Japan) scintillation
recording systems. The original binary data can be downloaded from
the Space Group archive, available on the Homepage.
4. To run IDL:
a. click on the IDL icon
b. choose File Open
c. click anywhere in the file
d. click on the File menu
e. click on the Compile/Run-the program starts running
f. additional files might be generated containing various
parameters such as ASC format of the binary scintillation files,
scintillation index S4, the slopes (with the standard deviation)
of scintillation spectra using both Fourier and Wavelet analysis
techniques, the frequency (in Hz) of the maximum ionospheric
disturbances etc.
g. graphs will be generated depicting raw/detrended
scintillation spectra, multiple scintillation spectra
(Fourier/Wavelet), the contours of the disturbance magnitude
(coluor coded) etc.
h. other scintillation data analysis can be performed by an
operator skilled in the standard IDL language.
NOVEL APPROACH TO VHF SCINTILLATION ANALYSIS USING THE
WAVELET TRANSFORM TECHNIQUES
1. Introduction
Spectral analysis is a recognised tool used to investigate
the frequency distribution (power spectra) of inospheric
inhomogeneities leading to the rapid fading (scintillations) in
radio-satellite VHF/UHF transmissions. For example, the structure
of ionospheric irregularities (e.g. the degree of their
anisotropy) can be deduced from the standard Fourier data analysis
as presented by Wernik et al. (1990).
It well known that the Fourier Transform (FT) analysis has
some major drawbacks which limit its usefulness in the
mathematical interpretation of real physical phenomena. For
example, FT can define scintillation spectra in a limited temporal
region under the assumption that the character of scintillations
remains the same over an infinite time span. Thus stationarity of
scintillation spectra is assumed a priori which is seldom true.
This limitation is largely overcome by using the Wavelet Transform
(WT) technique. WT is essentially a windowed FT where the window
can be translated and dilated in time. In other words, WT defines
the scintillation spectra over a short time region without the
limitation of FT; non-stationary plasma turbulences (leading, for
example, to scintillations) can be accurately studied over a
number of short time intervals. This is particularly applicable to
mid-latitude ionospheric scintillations where scintillations occur
in short patches (so-called P-type scintillations as defined by
Hajkowicz,1994). WT has been applied to high-latitude ionospheric
disturbances (Lagoutte et al.,1992) and to low frequency substorm
oscillations (Holter et al., 1994).
2. Results
I have investigated during the special leave from the
Queensland University the application of the IDL to both the FT
and WT techniques. Initially, it was necessary to familirise
myself with a new programming language of IDL ( a mixture of
C-language and Fortran, combined with the Window techniques). With
assistance of Prof. Andrew Wernik and his programmer Ms. Dorota
Rusiniak a number of programs have been written which
considerably expand the ionospheric scintillation analysis
techniques. Thus, a large number of mid-latitude scintillations
recorded at Brisbane at 1991-1996 can more efficiently analysed
using the IDL programs. The inherited setback of the Satdan
software was its sensitivity to a specific Unix environment
which made it difficult to use on other Unix systems. This was
particularly noted when the program was applied for
scintillation analysis in Japan, in association with the
Japanese-Australian scintillation project. This setback is now
overcome as the IDL software will be purchased to operate in both
countries.
3. The IDL programs
READ.PRO contains information about the IDL programs. It is
summarise here as follows:
1.EXTRACT.PRO
READS SCINT. BINARY FILES AND SELECTS DATA SEGMENTS WRITING TO TAR.DAT
THEN WRITES TO A SHORTER FILE TAR1.DAT AND PLOTS THE CORRESPONDING
GRAPH OF THE COMPLETE SINGLE RECORD (IN 3 PARTS)
2. EXTRACTA.PRO
IS USED FIRST TO EXAMINE THE WHOLE BINARY SCINT.FILE AND THEN THE
PERIOD OF INTEREST CAN BE SELECTED BY SPECIFYING THE TIME SPAN IN
DATA NUMBERS, PLOTTING THE SELECTED PORTION OF THE DATA.
3. FFT10D.PRO
CALCULATE SPECTRA (THE SLOPE AND STANDARD DEVIATION) AND
SCINTILLATION INDEX S4
4.AUFORM10.PRO
PROGRAM DRAWS SCINTILLATIONS DATA FOR UP TO 2 STATIONS IN A PRESET
TIME INTERVAL
5. AUPS.PRO
GENERATES POSTSCRIPT FILES
6. FFT10A.PRO
DRAWS UP TO 10 SPECTRA (FOR UP TO 2 STATIONS) ON A SCREEN AND
CALCULATES THE SLOPE Q AND S4
7.CZYT.PRO
CREATES 2 ARRAYS FROM 2 COLUMNS OF DATA AND PLOTS
8. MORLET10.PRO
DISPLAYS MAGNITUDE OF WAVELET CONTOURS AND CORRESPONDING
SCINT. DATA
9.MORLET11.PRO
SAME AS (9), COLOUR ENHANCED, DISPLAYS SPECTRA AT PRESET TIME
INTERVALS.
10. MORLETA.PRO
SAME AS (9), PRODUCES FILE SLOP.DAT-SLOPES AND ERRORS FROM THE
WAVELET ANALYSIS
11. MORLETB.PRO- PRODUCES CONTOUR SPECTRA FOR 2 STATIONS
SIMULTANEOUSLY
12. MORLET12.PRO
DISPLAY CONTOUR SPECTRA ON BLACK BACKGROUND (GOOD COLOR SCALE),
ALLOWS TO PLOT THE MAXIMUM FREQUENCY FROM THE CONTOURS, ON IDL
COMMAND )
13. MORLET13.PRO
DISPLAY CONTOURS SPECTRA ON BLACK BACKGROUND (GOOD COLOR SCALE),
ALLOWS TO PLOT THE MAXIMUM FREQUENCY FROM THE CONTOURS, ON IDL
COMMAND (at the end)
DISPLAY MAXIMUM FREQUENCY OF SPECTRUM,GENERATES FR.DAT OF THE
FREQUENCY
DISPLAYING GRAPHS AT HIGH RESOLUTION (ZOOM TECHNIQUES)
TO ZOOM A PART OF GRAPH:AT GRAPH CTRL-A,IDL>ZOOM.CLICK ON THE PART
TO DISPLAY HIGH RESOLUTION GRAPHS:
STEPS:IN FILE MENU USE PREFERENCES THEN GRAPHIC WINDOW SET 400,400
RUN A FILE, E.G. FFT10D.PRO TO CREATE QPIC.DAT,EXIT FROM FILES
FROM IDL RUN WEXAMPLE
LOAD QPIC.DAT AND VIEW
References.
Hajkowicz, L.A. 1994a. Types of ionospheric scintillations in
southern mid-latitudes during the last sunspot maximum. J. Atmos.
Terr. Phys. 56, 391.
Holter, O.Roux,A.,Altman, C.,Perraut,S.,Pecseli, H., Trulsen, J.,
B.Lybekk and Pedersen, A. Wavelet analysis of low fequency
substorm oscillations Proc. of the Second Int. Conf. on
Substorms, Fairbanks, Alaska, March 7-11,1994,358-590, 1994
Lagoutte, D.,Cerisier,J.C., Plagnaud J.L., Villain, J.P. and
Forget, B. High latitude ionospheric turbulence studied by means
of the wavelet transform, J.atmos.terr.Phys.,54,1283-1293,1992
Wernik, A.W. Methods of data analysis for resolving nonlinear
phenomena, Modern Ion.Science, Max Planck Institute for
Aeronomy,322-345,1996.
Wernik, A.,Liu,C.H.,Franke,S.J. and Gola, M. High latitude
irregularity spectra deduced from scintillation measurments Radio
Sci. 25, 883-895,1990.
For further information on the use of analysis programs or to request files not available, please contact us.
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Last updated 10/01/1997 by Mark Keir