Voyager 2 Jupiter Plasma Wave Spectrometer (PWS) Resampled Spectrum Analyzer, Version 1.0, 1 h Average Data

* Data Set Overview\n* =================\n\nThis Data Set consists of Electric Field Spectrum Analyzer Data from the Voyager 2 Plasma Wave Subsystem obtained during the entire Mission. Data after 2013-12-31 will be added to the Archive on subsequent Volumes. The Data Set encompasses all Spectrum Analyzer Observations obtained in the Cruise Mission Phases before, between, and after the Jupiter and Saturn Encounter Phases as well as those obtained during the two Encounter Phases.\n\nThe Voyager 2 Spacecraft travels from Earth to beyond 100 AU over the Course of this Data Set. To provide some Guidance on when some Key Events occurred during the Mission, the following Table is provided.\n\n+----------------------------------------------------------------+\n| Date       | Event                                             |\n------------------------------------------------------------------\n| 1977-08-20 | Launch                                            |\n| 1979-07-02 | First inbound Bow Shock Crossing at Jupiter       |\n| 1979-08-03 | Last outbound Bow Shock Crossing at Jupiter       |\n| 1981-08-24 | First inbound Bow Shock Crossing at Saturn        |\n| 1981-08-31 | Last outbound Bow Shock Crossing at Saturn        |\n| 1982-04-26 | 10 AU                                             |\n| 1983-08-30 | Onset of first major LF Heliospheric Radio Event  |\n| 1986-01-24 | First inbound Bow Shock Crossing at Uranus        |\n| 1986-01-29 | Last outbound Bow Shock Crossing at Uranus        |\n| 1986-05-26 | 20 AU                                             |\n| 1989-08-07 | 30 AU                                             |\n| 1989-08-24 | First inbound Bow Shock Crossing at Neptune       |\n| 1989-08-28 | Last outbound Bow Shock Crossing at Neptune       |\n| 1992-07-06 | Onset of second major LF Heliospheric Radio Event |\n| 1993-05-08 | 40 AU                                             |\n| 1996-10-10 | 50 AU                                             |\n| 2000-01-27 | 60 AU                                             |\n| 2002-11-01 | Onset of third major LF Heliospheric Radio Event  |\n| 2003-04-21 | 70 AU                                             |\n| 2006-07-01 | 80 AU                                             |\n| 2009-09-03 | 90 AU                                             |\n| 2012-11-04 | 100 AU                                            |\n+----------------------------------------------------------------+\n\n* Data Sampling\n* =============\n\nThis Data Set consists of average and peak Wave Electric Field Intensities accumulated over one hour Intervals from the Voyager 2 Plasma Wave Receiver Spectrum Analyzer obtained during the entire Mission. For each one hour Time Interval Squares of the calibrated Electric Field Measurements obtained during each hour-long Interval in each of the sixteen Spectrum Analyzer Channels are summed and then divided by the Number of Measurements. The Square Root of the resulting Value is obtained and stored as the average Electric Field Strength for the respective Channel. During the same hour-long Interval, the maximum Electric Field Strength acquired in each of the sixteen Channels is also recorded and stored as the peak Electric Field Strength for the respective Channel. Hence, for each hour, an average and peak Electric Field Spectrum from 10 Hz to 56.2 kHz is obtained. The sixteen Spectrum Analyzer Channels have Center Frequencies that range from 10 Hz to 56.2 kHz and are logarithmically spaced in Frequency, four Channels per Decade. The Time associated with each peak and average Spectrum is the Time of the Beginning of the Averaging Interval. Given Variations in the Sweep Rate of the Instrument (from a minimum of 4 s per sweep to a maximum of 96 s per sweep) the maximum Number of Samples in an hour-long Interval can range from 900 to 38. Data Gaps within the Interval can further reduce the Number of Samples.\n\nDuring Data Gaps where complete Spectra are missing, no Entries exist in the File, that is, the Gaps are not Zero-filled or Tagged in any other way.\n\n* Data Processing\n* ===============\n\nThe Spectrum Analyzer Data are a continuous (where Data are available) low resolution Data Set which provides Wave Intensity as a Function of Frequency (sixteen log-spaced Channels) and Time (one Spectrum per Time Intervals ranging from 4 s to 96 s in the full-resolution Data Set, depending on Telemetry Mode.) This Data Set includes 1 hr average and peak Values for each Channel. The Data are typically plotted as Amplitude versus Time for one or more of the Channels in a Strip-Chart like Display, or can be displayed as a Frequency-Time Spectrogram using a Grayscale Bar or a Color Bar to indicate Amplitude. With only sixteen Channels, it is usually best to stretch the Frequency Axis by interpolating from one Frequency Channel to the next either linearly or with a Spline Fit. One must be aware if the Frequency Axis is stretched that more Resolution may be implied than is really present.\n\nThe Measurements provided in the average and peak Electric Field Spectra included in this Data Set are in Units of Electric Field (V/m).\n\nSpectral 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.\n\n* specdens=(efield(ichan))^2/bandwidth(ichan)\n\nFinally, Power Flux may be obtained by dividing the Spectral Density by the Impedance of Free Space in Ohms:\n\n* pwrflux=(efield(ichan))^2/bandwidth(ichan)/376.73\n\nThe Center Frequencies and Bandwidths of each PWS Spectrum Analyzer Channel for the Voyager 2 PWS are given below:\n\n+----------------------------------------+\n| Channel | Center Frequency | Bandwidth |\n------------------------------------------\n| 1       | 10.0 Hz          | 2.16 Hz   |\n| 2       | 17.8 Hz          | 3.58 Hz   |\n| 3       | 31.1 Hz          | 4.50 Hz   |\n| 4       | 56.2 Hz          | 10.7 Hz   |\n| 5       | 100 Hz           | 13.8 Hz   |\n| 6       | 178 Hz           | 28.8 Hz   |\n| 7       | 311 Hz           | 39.8 Hz   |\n| 8       | 562 Hz           | 75.9 Hz   |\n| 9       | 1.00 kHz         | 75.9 Hz   |\n| 10      | 1.78 kHz         | 151 Hz    |\n| 11      | 3.11 kHz         | 324 Hz    |\n| 12      | 5.62 kHz         | 513 Hz    |\n| 13      | 10.0 kHz         | 832 Hz    |\n| 14      | 17.8 kHz         | 1260 Hz   |\n| 15      | 31.1 kHz         | 2400 Hz   |\n| 16      | 56.2 kHz         | 3800 Hz   |\n+----------------------------------------+\n\nA Failure in the Voyager 2 Flight Data System which occurred about three Months after Launch has adversely affected the Calibration of PWS Channels 9 through 16. An Algorithm has been devised to partially correct for this Failure, and has proven useful for Voyager 2 Jupiter, Saturn, Uranus, and Neptune Encounters, but is not valid for Earth-Jupiter Cruise and may be modified in the Future. The following Implementation of this Correction Algorithm in FORTRAN assumes that uncalibrated Data Numbers are stored in a sixteen-element Integer Array, idn, with the Array Index equal to the PWS Channel Number:\n\n* c 'the old Noise level.' for VG2 PWS\n*\n* real tonl(9:16) /2.0,1.0,-1.0,-2.0,-3.0,1.0,2.0,1.0/\n*\n* do ichan=9,16\n* if(idn(ichan).gt.0) then\n* if(idn(ichan).lt.64) idn(ichan)=64\n* if(idn(ichan).le.72) then\n* idn(ichan)=int(tonl(ichan)-530.4+8.6*float(idn(ichan)))\n* else\n* idn(ichan)=int(tonl(ichan)+20.113+0.99*float(idn(ichan)))\n* end if\n* end if\n* end do\n\nThis Correction has been applied to the appropriate Data in this Data Set.\n\nAdditional Information about this Data Set and the Instrument which produced it can be found elsewhere in this Catalog. A complete Instrument Description can be found in (Scarf and Gurnett, 1977).\n\n* Data\n* ====\n\nThe average and peak Spectrum Analyzer Data are a continuous (where Data are available) low resolution Data Set which provides Wave Intensity as a Function of Frequency (sixteen log-spaced Channels) and Time (one Spectrum per hour). Each Sample is a floating point Electric Field Strength in Units of V/m.\n\n* Ancillary Data\n* ==============\n\nNone\n\n* Coordinates\n* ===========\n\nThe Electric Dipole Antenna detects Electric Fields

Tags: waves-passive
Organization: National Aeronautics and Space Administration