Data Set Overview : This data set consists of electric field waveform samples from the Voyager 2 Plasma Wave Subsystem waveform receiver obtained during the entire mission. Data after 2006-03-07 will be added to the archive on subsequent volumes. The data set encompasses all waveform observations obtained in the cruise mission phases before, between, and after the Jupiter, Saturn, Uranus, and Neptune encounter phases as well as those obtained during the four encounter phases. The Voyager 2 spacecraft travels from Earth to beyond 80 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 : The waveform is sampled at 4-bit resolution through a bandpass filter with a passband of 40 Hz to 12 kHz. 1600 samples are collected in 55.56 msec (at a rate of 28,800 samples per second) followed by a 4.44-msec gap. Each 60-msec interval constitutes a line of waveform samples. The data set includes frames of waveform samples consisting of up to 800 lines, or 48 seconds, each. The telemetry format for the waveform data is identical to that for images, hence the use of line and frame as constructs in describing the form of the data. Data Processing : Because there is no direct method for calibrating these data and because the raw format of packed, 4-bit samples is space-efficient, these data are not processed for archiving. The data may be plotted in raw form to show the actual waveform; this is useful for studying events such as dust impacts on the spacecraft. But the normal method of analyzing the waveform data is by Fourier transforming the samples from each line to arrive at an amplitude versus frequency spectrum. By stacking the spectra side-by-side in time order, a frequency-time spectrogram can be produced. Data : The waveforms are collections of samples of the electric field measured by the dipole electric antenna at a rate of 28,800 samples per second. The 4-bit samples provide sixteen digital values of the electric field with a linear amplitude scale, but the amplitude scale is arbitrary because of the automatic gain control used in the waveform receiver. The instantaneous dynamic range afforded by the 4 bit samples is about 23 dB, but the automatic gain control allows the dominant signal in the passband to be set at the optimum level to fit within the instantaneous dynamic range. With the gain control, the overall dynamic range of the waveform receiver is about 100 dB. The automatic gain control gain setting is not returned to the ground, hence, there is no absolute calibration for the data. However, by comparing the waveform spectrum derived by Fourier transforming the waveform to the spectrum provided by the spectrum analyzer data, an absolute calibration may be obtained in most cases. Ancillary Data : None Coordinates : The electric dipole antenna detects electric fields in a dipole pattern with peak sensitivity parallel to the spacecraft x-axis. However, no attempt has been made to correlate the measured field to any particular direction such as the local magnetic field or direction to a planet. This is because the spacecraft remains in a 3-axis stabilized orientation almost continuously, and these data are not obtained during the infrequent calibration turns. Furthermore, the automatic gain control feature would tend to counteract any orientation-dependent amplitude variations.

Overview : The Spacecraft Event Time (SCET) originally included in Cxxxxxxx.DAT files is very often incorrect or missing (zero), especially through the Jupiter encounter. It is important to use the SCET which is provided in the Cxxxxxxx.LBL file for the .DAT file your are using. The SCET from the .LBL file is the best known time for the data, based on the use of the appropriate SPICE kernel. The originally-provided data file includes no consistently present spacecraft identification. The SPACECRAFT_ID in the .LBL file is the most reliable indicator of the host spacecraft. Because the .LBL files are detached from the .DAT files, it is possible to lose the SCET and SPACECRAFT_ID information. Therefore, an ASCII entry has been added to spare words in the .DAT file header at byte 249 including SPACECRAFT_ID, spacecraft clock partition (rollover indicator), and SCET. In both the PDS .LBL file and this ASCII SCET entry in the .DAT file header, the SCET refers to the time of the first sample of the 48-second frame, assuming all data are present. For example, if the first 10 seconds of data is missing, the SCET provided in these two locations would be 10 seconds earlier than that of the first data present in the frame. Given this time, the line and sample number of a measurement provides an accurate time for the sample with the understanding that the time between the beginning of two adjacent lines is 60 milliseconds and the time between samples is 34.72 microseconds. This data set includes all available waveform receiver data obtained from launch through the end of 2006. Note that for data acquired during the Voyager 2 Jupiter Encounter mission phase, it is usually the case that the first 16 samples (8 bytes) of waveform data per data line are invalid. Hence, it is strongly recommended that these bytes be skipped by any analysis software. Beginning on 1998-09-15, the telecom performance would no longer support playing data off the tape recorder at its lowest playback rate. As a work-around, four data lines of every five are discarded during playback beginning with this date. For various reasons, the one data line out of five which is returned to the ground are repeated 5 times in the *.DAT files. The DATA_LINES parameter in the *.LBL file, therefore, counts only UNIQUE valid data lines; the maximum DATA_LINES after this date, then is 160. There has been no attempt to clean various interference signals from the data. Most of these can normally be easily seen in frequency-time spectrograms as narrowband, fixed-frequency tones. The most common include narrow-band tones at 2.4 and 4.8 kHz which are power supply harmonics. There is sometimes a tone near 1.7 kHz which is associated with the operation of the spacecraft gyros. The spacecraft tape recorder results in a rather intense band in the frequency range of a few hundred Hertz. There are few times when the data in this frequency range can be used. However, there are times when the real signals in this frequency range can exceed the intensity of the interference sufficiently so that the frequency range near a few hundred Hz can be used. Use of the spectrum analyzer data can be of use to determine when these time periods occur. The stepper motor of the LECP instrument also interferes in the frequency range of a few hundred Hz, but for periods of a few seconds. The LECP interference is very intense and captures the automatic gain control so that real signals, even where there is no interference, will appear to decrease in amplitude until the LECP interference fades in amplitude. The PLS instrument periodically interferes at 400 Hz and odd harmonics because of a 400-Hz square wave used to modulate a grid in the detector. The PLS interference lasts for several seconds and ends abruptly. Telemetry errors result in a fairly graceful degradation of the waveform data. Assuming the telemetry errors are randomly occurring bursts, they typically appear as an enhanced background level in the spectrum. Since the bursts are short, their Fourier transform is a broadband spectrum. When looking for relatively narrowband features or features with distinct frequency-time characteristics, the result of the bursts simply reduce the signal-to-noise in the spectrum. One way of reducing the effect of burst telemetry errors is to pass the waveform data through a low-pass filter to despike it, prior to running the Fourier transform. The waveform data is not subject to the negative effects of the failure in the Voyager 2 Flight Data System which reduces the sensitivity of the spectrum analyzer and affects the calibration above 1 kHz. In fact, use of the 1-12 kHz waveform data is an effective way of avoiding the problems with the spectrum analyzer data in this frequency range. Beginning on about May 20, 2001 the Voyager 2 wideband receiver began to display degraded operation and by September of 2002, the receiver showed virtually no response. Attempts to playback wideband data from Voyager 2 have ceased. File Edits : Minor edits have been applied to the original EDR files in order to provide reliable spacecraft and time identification and to adjust for missing file header records. Detailed format information is provided elsewhere, but briefly, an ASCII text string has been inserted starting at byte 249 of the first record of each file. This string provides the most reliable spacecraft and time identification and is in the format: VOYAGER-n PWS n/nnnnn.nn yyyy-mm-ddThh:mm:ss.sssZ\0\0 In cases where the EDR file header record was missing, a pseudo header was created by duplicating the first available record of the file, inserting the ASCII text string starting at byte 249, and zero-filling the remaining bytes of the record. Since these files are a possible source of confusion for anyone attempting to extract detailed engineering information from EDR headers, they are listed below. The first element of the directory path is actually the volume name. VGPW_2001/DATA/P2/V2P2_001/C1848121.DAT VGPW_2001/DATA/P2/V2P2_002/C1871937.DAT VGPW_2001/DATA/P2/V2P2_056/C2044131.DAT VGPW_2001/DATA/P2/V2P2_059/C2047252.DAT VGPW_2001/DATA/P2/V2P2_060/C2047327.DAT VGPW_2001/DATA/P2/V2P2_060/C2047328.DAT VGPW_2001/DATA/P2/V2P2_060/C2047330.DAT VGPW_2001/DATA/P2/V2P2_066/C2053850.DAT VGPW_2001/DATA/P2/V2P2_066/C2053851.DAT VGPW_2001/DATA/P2/V2P2_083/C2056838.DAT VGPW_2001/DATA/P2/V2P2_084/C2056929.DAT VGPW_2001/DATA/P2/V2P2_094/C2058832.DAT VGPW_2001/DATA/P2/V2P2_122/C2072015.DAT VGPW_2001/DATA/P2/V2P2_126/C2082839.DAT VGPW_2001/DATA/P2/V2P2_135/C3168857.DAT VGPW_2001/DATA/P2/V2P2_145/C4798011.DAT Review : This archival data set was examined by a peer review panel prior to its acceptance by the Planetary Data System (PDS). The peer review was conducted in accordance with PDS procedures. Prior to creation of the final version of the archival data set, key elements of the archive were distributed for preliminary review. These included electronic versions of example PDS labels, CATALOG files, and Software Interface Specifications. These materials were distributed to PDS personnel, the experiment investigator, and others, as appropriate.