PWS16PC User's Guide
Introduction
PWS16PC is a PC version of the 'workhorse' display software used to survey
and analyze in detail the Voyager plasma wave receiver's 16-channel spectrum
analyzer data. It's basic function is to plot intensity as a function of
time for all 16 of the channels whose center frequencies run from 10 Hz to
56.2 kHz. The default plot is a strip-chart like display where the average
signal strength is plotted as a solid area above the baseline of each
channel and peak measurements determined over the same intervals as the
averages are plotted as a line over the averages. The ultimate temporal
resolution of the instrument is one complete spectrum every 4 seconds, so if
a very short time span is plotted (e.g. one-half hour) individual points are
plotted and there are no averages or peaks determined. Additional features
include using a gray scale to plot a frequency-time spectrogram; in this
form, pixels are interpolated between channels to give a smoothly-varying
appearance instead of the blocky look one would obtain with only 16 vertical
pixels. A color scale can also be used in the same way as the gray scale.
The starting time of a plot is specified at the command line and the length
of the plot in hours (default = 24) can be chosen over a wide range from less
than 1 hour to a few days. The minimum and maximum amplitude range can
be specified, and the range of channels can also be selected if all 16
channels are not required.
Setup
The software is designed to run directly from the CD-ROM for PC's with
800 x 600 16 color display capabilities. However, for some setups, the
configuration will need to be modified (PWS16PC.CFG). If the program
fails to run from it's location in the SOFTWARE directory on the CD-ROM,
the user can copy all of the files:
PWS16PC.EXE
PWS16PC.CFG
PWS16PC.HLP
into a directory on a magnetic disk, edit the .CFG file, and run
the program from that directory. The most likely reasons for the
program to require a different configuration would be incompatible
paths for the data or calibration files (which might occur if the
software was to be used on a CD-ROM with a different directory
structure) or if the user's display is different from the default
selected in the original .CFG file. For the Voyager 2 Neptune PDS CD-ROM
labeled USA_NASA_PDS_VG_1001, Version 1, the configuration file needs
to point to the following paths:
CAL_PATH=\DATA\PWS\SA\4S\IOWA\.
V1DATA_PATH=\DATA\PWS\SA\4S\IOWA\. (although there is no VGR 1 data on the
Neptune disk)
V2DATA_PATH=\DATA\PWS\SA\4S\IOWA\.
For other versions of PDS CD-ROMs the paths should read \DATA\PWS\SA\4S\.
Subdirectories include the object code and source code for the software.
These are provided in the unlikely case the code would need to be re-linked
or re-compiled and re-linked. The source code is also instructive for
one who would like to develop other analysis code for the data or to
do maintenance on the software.
Starting the program
The program is invoked by setting the default directory to that containing
the PWS16PC.EXE and associated files (either on the CD-ROM or on the
hard disk as suggested above). At the system prompt, type PWS16PC and
❮Return❯. The program will respond with the ❯ prompt. The minimum information
required is
❯spacecraft=n, year=yy, day=ddd ❮Return❯
where n is 1 for Voyager 1 or 2 for Voyager 2, yy are the year of century
for the time interval desired, and ddd is the day of year. This will
result in a plot beginning at hour 00 of day ddd and having a duration
of 24 hours. Full details on other commands are given below and can
be accessed from within the program by typing HELP at the ❯ prompt.
Entering Commands
Plotting parameters are entered in a freeform manner by way of keywords and
optional value assignments of the form KEY=value. Key-value pairs may be
given in any order separated by spaces or commas. The following keys are
recognized by PWS16PC:
KEYWORD DEFAULT VALUE EXAMPLE COMMENT
spacecraft (none) spacecraft=2 Voyager 1 or 2
year (none) year=86 SCET (Spacecraft Event Time) year
day (none) day=24 SCET day of year
hour 00 hour=14 SCET hour of day
minute 00 minute=30 SCET minute of hour
span 24 span=4 plot length in hours
units 5 units=6 data units:
(1) uncalibrated
(2) LOG calibrated volts (V)
(3) LOG RMS volts (Vrms)
(4) LOG electric field (V/M)
(5) LOG RMS electric field (Vrms/M)
(6) LOG spectral density (V^2/M^2/Hz)
(7) LOG power flus (W/M^2/Hz)
(Note: because the filter bandwidths are approximately a constant percentage
of the center frequency, units 6 and 7 will show a large noise level variation
from low to high frequencies and these two options will work best for plots of
4 or fewer channels.)
nopeaks N nopeaks suppress plotting of peaks
min (unit dependent) min=-7 minimum data to be plotted
max (unit dependent) max=-1 maximum data to be plotted
cmin 1 cmin=5 lowest channel to be plotted
cmax 16 cmax=8 highest channel to be plotted
c1 1 c1=5 first channel to be plotted
c2 2 c2=7 second channel to be plotted
. . . .
. . . .
. . . .
c16 16 c16=1 sixteenth channel to be plotted
- N - command continued on next line
end N end end processing and exit
NOTE: keywords must not be abbreviated. An entry like "KEY" is equivalent
to "KEY=Y" or "KEY=1". Key values may be integer or floating point or the
letters Y, N, T or F. Default values are set to the previous entries.
The keywords CMIN and CMAX may be used to specify the range of channels to
be plotted or if for example two non-adjacent channels needed to be plotted,
then the keywords C1 and C2 could be used.
EXAMPLE:
❯ spacecraft=2 year=86 day=24 span=3.5 cmin=7 cmax=9
The above would plot Voyager 2 data from 86 024 0000 - 0330, channels 7-9,
(311, 562, 1000 Hz) in default RMS electric field units.
ADDITIONAL FEATURES:
KEYWORD DEFAULT VALUE EXAMPLE COMMENT
SNAPSHOT N snapshot=on Snap Shot of averages and/or peaks
GRAY N gray=off Plot intensity in shades of gray
COLOR N color=on Plot intensity in 16 colors
SHELL shell shell to DOS
RUN run run a program
INPUT input=server change input method
Known Errors:
None
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