• Data Set Overview
• =================

This 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.

The 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.

+----------------------------------------------------------------+
| Date | Event |

| 1977-08-20 | Launch |
| 1979-07-02 | First inbound Bow Shock Crossing at Jupiter |
| 1979-08-03 | Last outbound Bow Shock Crossing at Jupiter |
| 1981-08-24 | First inbound Bow Shock Crossing at Saturn |
| 1981-08-31 | Last outbound Bow Shock Crossing at Saturn |
| 1982-04-26 | 10 AU |
| 1983-08-30 | Onset of first major LF Heliospheric Radio Event |
| 1986-01-24 | First inbound Bow Shock Crossing at Uranus |
| 1986-01-29 | Last outbound Bow Shock Crossing at Uranus |
| 1986-05-26 | 20 AU |
| 1989-08-07 | 30 AU |
| 1989-08-24 | First inbound Bow Shock Crossing at Neptune |
| 1989-08-28 | Last outbound Bow Shock Crossing at Neptune |
| 1992-07-06 | Onset of second major LF Heliospheric Radio Event |
| 1993-05-08 | 40 AU |
| 1996-10-10 | 50 AU |
| 2000-01-27 | 60 AU |
| 2002-11-01 | Onset of third major LF Heliospheric Radio Event |
| 2003-04-21 | 70 AU |
| 2006-07-01 | 80 AU |
| 2009-09-03 | 90 AU |
| 2012-11-04 | 100 AU |
+----------------------------------------------------------------+

• Data Sampling
• =============

This Data Set consists of Full Resolution edited, Wave Electric Field Intensities from the Voyager 2 Plasma Wave Receiver Spectrum Analyzer obtained during the entire Mission. For each Time Interval, a Field Strength is determined for each of the sixteen Spectrum Analyzer Channels whose Center Frequencies range from 10 Hz to 56.2 kHz and which are logarithmically spaced in Frequency, four Channels per Decade. The Time associated with each Set of Intensities (sixteen Channels) is the Time of the Beginning of the Scan. The Time between Spectra in this Data Set vary by Telemetry Mode and range from 4 s to 96 s. During 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. 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.

For the Cruise Data Sets, the Timing of Samples is dependent upon the Spacecraft Telemetry Mode. In principle, one can determine the Temporal Resolution between Spectra simply by noting the Difference in Time between two Records in the Files. In some Studies, more precise Timing Information is necessary. Here, we describe the Timing of the Samples for the PWS Low Rate Data as a Function of Telemetry Mode.

The PWS Instrument uses two Logarithmic Compressors as Detectors for the sixteen Channel Spectrum Analyzer, one for the bottom (lower frequency) eight Channels, and one for the upper (higher frequency) eight Channels. For each Bank of eight Channels, the Compressor sequentially steps from the lowest frequency of the eight to the highest in a regular Time Step to obtain a complete Spectrum. At each Time Step, the higher frequency Channel is sampled 0.125 s prior to the lower frequency Channel so that the Channels are sampled in the following order with Channel 1 being the lowest frequency Channel (10 Hz) and Channel 16 being the highest (56.2 kHz): 9, 1, 10, 2, 11, 3, ..., 15, 7, 16, 8. The primary Difference between the various Data Modes is the Stepping Rate from one Channel to the next (ranging from 0.5 s to 12 s, corresponding to the Temporal Resolutions between complete Spectra of 4 s to 96 s).

In the following Table, we present the Hexadecimal ID for the various Telemetry Modes, the Mode Mnemonic ID, the Time between Frequency Steps, and the Time between complete Spectra. We also provide the Offset from the Beginning of the Instrument Cycle (one complete Spectrum) identified as the Time elapsed from the Time Tag of each Record to the Time of the Sampling for the first high-frequency Channel (Channel 9) and for the first low-frequency Channel (Channel 1).

+--------------------------------------------------------------------------------------------------------------------------+
| MODE (Hex) | MODE ID | Frequency Step (s) | Spectra (s) | High Freq. Offset (s) | Low Freq. Offset (s) | Notes |

| 01 | CR-2 | 0.5 | 4.0 | 0.425 | 0.4325 | |
| 02 | CR-3 | 1.2 | 9.6 | 1.125 | 1.1325 | |
| 03 | CR-4 | 4.8 | 38.4 | 0.425 | 0.4325 | |
| 04 | CR-5 | 9.6 | 76.8 | 0.425 | 0.4325 | |
| 05 | CR-6 | 12.0 | 96.0 | 0.9275 | 0.935 | |
| 06 | CR-7 | | | | | Not implemented |
| 07 | CR-1 | 0.5 | 4.0 | 0.225 | 0.2325 | |
| 08 | GS-10A | 0.5 | 4.0 | 0.425 | 0.4325 | Same as GS-3 |
| 0A | GS-3 | 0.5 | 4.0 | 0.425 | 0.4325 | |
| 0C | GS-7 | 0.5 | 4.0 | 0.425 | 0.4325 | Same as GS-3 |
| 0E | GS-6 | 0.5 | 4.0 | 0.425 | 0.4325 | Same as GS-3 |
| 16 | OC-2 | 0.5 | 4.0 | 0.425 | 0.4325 | Same as GS-3 |
| 17 | OC-1 | 0.5 | 4.0 | 0.425 | 0.4325 | Same as GS-3 |
| 18 | †CR-5A | 0.5 | 4.0 | 0.425 | 0.4325 | |
| 19 | GS-10 | 0.5 | 4.0 | 0.425 | 0.4325 | Same as GS-3 |
| 1A | GS-8 | 0.5 | 4.0 | 0.425 | 0.4325 | Same as GS-3 |
| 1D | †UV-5A | 0.5 | 4.0 | 0.425 | 0.4325 | Same as CR-5A |
+--------------------------------------------------------------------------------------------------------------------------+

†In CR-5A and UV-5A, the PWS is cycled at its 0.5 s per Frequency Step or 4 s per Spectrum Rate, but four Measurements are summed onboard in 10-bit Accumulators and these 10-bit Sums are downlinked. On the Ground, the Sums are divided by four, hence providing, in a sense, 16 s Averages. One of every 12 Sets of Sums is dropped onboard in order to avoid LECP Stepper Motor Interference.

• Data Processing
• ===============

The 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, depending on Telemetry Mode). 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 or 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. The Voyager PWS Calibration Table is given in an ASCII Text File named VG2PWSCL.TAB (for Voyager 2). This provides Information to convert the uncalibrated 'Data Number' Output of the PWS sixteen-channel Spectrum Analyzer to calibrated Antenna Voltages for each frequency Channel. Following is a brief Description of this File and a Tutorial in its 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 sixteen Frequency Channels of the PWS Spectrum Analyzer. Each Line contains Calibrations fo