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NASA Space Science Data Coordinated Archive Header



Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1979-02-28 to 1979-03-23


This description was generated automatically using input from the Planetary Data System.

Data Set Overview ================= Version 1.1 ----------This version 1.1 data set replaces the version 1.0 data set (DATA_SET_ID = VG1-J-PWS-2-SA-4.0SEC) previously archived with the PDS. Changes to this version include the upgrade of the associated labels and templates to PDS version 3 compliance. Data Set Description -------------------This data set consists of 4-second edited, wave electric field intensities from the Voyager 1 Plasma Wave Receiver spectrum analyzer obtained in the vicinity of the Jovian magnetosphere. For each 4-second interval, a field strength is determined for each of the 16 spectrum analyzer channels whose center frequencies range from 10 Hertz to 56.2 kiloHertz and which are logarithmically spaced in frequency, four channels per decade. The time associated with each set of intensities (16 channels) is the time of the beginning of the scan. During data gaps where complete 4-second spectra are missing, no entries exist in the file, that is, the gaps are not zero-filled or tagged in any other way. When one or more channels are missing within a scan, the missing measurements are zero-filled. Data are edited but not calibrated. The data numbers in this data set can be plotted in raw form for event searches and simple trend analysis since they are roughly proportional to the log of the electric field strength. Calibration procedures and tables are provided for use with this data set; the use of these is described below. Use of Voyager PWS Calibration Tables ------------------------------------The Voyager PWS calibration table is given in an ASCII text file named VG1PWSCL.TAB (for Voyager-1). This provides information to convert the uncalibrated 'data number' output of the PWS 16-channel spectrum analyzer to calibrated antenna voltages for each frequency channel. Following is a brief description of these files and a tutorial in their application. Descriptive headers have been removed from this file. The columns included are IDN, ICHAN01, ICHAN02, ICHAN03, ICHAN04, ICHAN05, ICHAN06, ... ICHAN16. The first column lists an uncalibrated data number followed by the corresponding value in calibrated volts for each of the 16 frequency channels of the PWS spectrum analyzer. Each line contains calibrations for successive data number values ranging from 0 through 255. (Data number 0 actually represents the lack of data since the baseline noise values for each channel are all above that.) A data analysis program may load the appropriate table into a data structure and thus provide a simple look-up scheme to obtain the appropriate voltage for a given data number and frequency channel. For example, the following VAX FORTRAN code may be used to load a calibration array for Voyager 1 PWS: real*4 cal (16,0:255) open ( unit=10, file='VG1PWSCL.TAB', status='old' ) do i=0,255 read (10,*) idn, (cal(ichan,i),ichan=1,16) end do close (10) Then, given an uncalibrated data value idn for the frequency channel ichan, the corresponding calibrated antenna voltage would be given by the following array reference: volts = cal (ichan, idn) This may be converted to a wave electric field amplitude by dividing by the effective antenna length in meters, 7.07 m. That is: efield = cal(ichan, idn) / 7.07 Spectral density units may be obtained by dividing the square of the electric field value by the nominal frequency bandwidth of the corresponding spectrum analyzer channel. specdens = (cal(ichan,idn)/7.07)**2 / bandwidth(ichan) Finally, power flux may be obtained by dividing the spectral density by the impedance of free space in ohms: pwrflux = (cal(ichan,idn)/7.07)**2/bandwidth(ichan) / 376.73 Of course, for a particular application, it may be more efficient to apply the above conversions to the calibration table directly. The center frequencies and bandwidths of each PWS spectrum analyzer channel for each Voyager spacecraft are given below: VOYAGER 1 PWS SPECTRUM ANALYZER Voyager-1 Channel Center Frequency Bandwidth 1 10.0 Hz 2.99 Hz 2 17.8 Hz 3.77 Hz 3 31.1 Hz 7.50 Hz 4 56.2 Hz 10.06 Hz 5 100. Hz 13.3 Hz 6 178. Hz 29.8 Hz 7 311. Hz 59.5 Hz 8 562. Hz 106. Hz 9 1.00 kHz 133. Hz 10 1.78 kHz 211. Hz 11 3.11 kHz 298. Hz 12 5.62 kHz 421. Hz 13 10.0 kHz 943. Hz 14 17.8 kHz 2110 Hz 15 31.1 kHz 4210 Hz 16 56.2 kHz 5950 Hz Additional information about this data set and the instrument which produced it can be found elsewhere in this catalog. An overview of the data in this data set can be found in [SCARFETAL1979] and a complete instrument description can be found in [SCARF&GURNETT1977]. Data Object Type : Time Series Processing Level ID : 4 Software Flag : Y Processing Start Time : 1988-02-01T Processing Stop Time : N/A Parameters ========== Sampling Parameter Name : TIME Sampling Parameter Resolution : 4.0 Minimum Sampling Parameter : 1977-09-05T14:20 Maximum Sampling Parameter : N/A Sampling Parameter Interval : 4.0 Minimum Available Sampling Int : 4.0 Sampling Parameter Unit : SECOND Data Set Parameter Name : PLASMA WAVE SPECTRUM Noise Level : 5.E-6 Data Set Parameter Unit : V/m Processing ========== Software Name : CDMAKE Source Data Set ID : VG1-J-PWS-2-SMS Product Data Set ID : VG1-J-PWS-2-SA-4.0SEC Node ID : F&P-IOWA Software Release Date : 1988-08-01T Software Type : FORTRAN Cognizant Full Name : MR. LARRY J. GRANROTH Software Accessibility Desc : NOT FOR PUBLIC USE CDMAKE is primarily a data format translation routine which is used to convert Voyager PWS MSF tape files to CD files. The MSF, or Master Science Files, are produced at the University of Iowa as the primary, ordered, full-information PWS spectrum analyzer data set. The CD files contain uncalibrated, full-resolution PWS data with minimal ancillary data in a simplified format which may be used in CD-ROM production. Software ======== PWS16PC ------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 software is designed to run directly from the CD-ROM for PC's with 800 x 600 16 color display capabilities. Data Coverage and Quality ========================= Filename Records Start Stop ---------------------------------------T790228 21480 1979-02-28 1979-03-01 T790301 21264 1979-03-01 1979-03-02 T790302 21492 1979-03-02 1979-03-03 T790303 17640 1979-03-03 1979-03-04 T790304 21408 1979-03-04 1979-03-05 T790305 21538 1979-03-05 1979-03-06 T790306 21023 1979-03-06 1979-03-07 T790307 21516 1979-03-07 1979-03-08 T790308 21252 1979-03-08 1979-03-09 T790309 21541 1979-03-09 1979-03-10 T790310 20712 1979-03-10 1979-03-11 T790311 21443 1979-03-11 1979-03-12 T790312 21072 1979-03-12 1979-03-13 T790313 21504 1979-03-13 1979-03-14 T790314 21468 1979-03-14 1979-03-15 T790315 21240 1979-03-15 1979-03-16 T790316 21168 1979-03-16 1979-03-17 T790317 21155 1979-03-17 1979-03-18 T790318 21313 1979-03-18 1979-03-19 T790319 21552 1979-03-19 1979-03-20 T790320 21324 1979-03-20 1979-03-21 T790321 21528 1979-03-21 1979-03-22 T790322 21349 1979-03-22 1979-03-23

These data are available on-line from the Planetary Data System (PDS) at:

Alternate Names

  • VG1-J-PWS-2-RDR-SA-4.0SEC-V1.1


  • Planetary Science: Fields and Particles

Additional Information



Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II



NameRoleOriginal AffiliationE-mail
Prof. Donald A. GurnettData ProviderUniversity of Iowa
Dr. William S. KurthGeneral ContactUniversity of
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