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 . The program will respond with the > prompt. The minimum information required is >spacecraft=n, year=yy, day=ddd 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