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JUNO E/J/SS WAVES CALIBRATED SURVEY FULL RESOLUTION V2.0 (PDS)

NSSDCA ID: PSFP-00790

Availability: Archived at NSSDC, accessible from elsewhere

Description

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

Data Set Overview

The Juno Waves calibrated full resolution survey data set includes all low rate science electric spectral densities from 50Hz to 41MHz and magnetic spectral densities from 50Hz to 20kHz with complete sweeps at 30, 10 and 1 second intervals depending on the instrument mode. This is a complete full resolution data set containing all low rate science data received from Waves from launch until the end of mission including near Earth checkout, the Earth flyby, the Jupiter orbits and all cruise data. Data are acquired from the Waves Low Frequency Receiver (LFR) and High Frequency Receiver (HFR) and are processed into spectra in flight. These data are presented as ASCII text spreadsheets for ease of use. This data set is intended to be the most comprehensive and complete data set included in the Juno Waves archive. Pre-rendered spectrograms generated from these data are included as well to lead the user to the particular data file(s) of interest. This data set should be among the first used of any in the Waves archive as it will lead one to the information required to locate more detailed products.

Parameters

This data set consists of electric and magnetic field spectral densities in the following frequency bands: Spectral Density Frequency Range Receiver, Band ---------------- ------------------ -----------------------Magnetic 50 Hz to 20 kHz LFR, B Electric 50 Hz to 20 kHz LFR, Lo E Electric 19 kHz to 150 kHz LFR, Hi E Electric 133 kHz to 3 MHz HFR (44 or 45), Baseband Electric 3 MHz to 41 MHz HFR (44 or 45), Hi Bands The frequency bands are derived from the analysis bandwidths of the Low Frequency Receiver (LFR) and High Frequency Receivers (HFR-44, HFR-45). The the center frequencies of the bins are roughly log spaced in frequency. The time between frequency sweeps depends on the instrument operating mode as follows: 1. Periapsis Cadence - 1 complete sweep per second 2. Intermediate Cadence - 1 complete sweep every 10 seconds 3. Apoapsis Cadence - 1 complete sweep every 30 seconds Additional cadences can be programmed in flight should the science or unknown operating constraints dictate. Typically electric measurements from 50 Hz to 150 kHz and magnetic measurements from 20 kHz to 20 kHz are measured simultaneously, however this is not always the case. Waves has the ability to sample solar panel switching noise and to mitigate this noise to a limited extent. When operating in this mode it is not possible to collect all data below 150 kHz simultaneously. In these instances time tags on the magnetic data will not line up with time tags on the corresponding electric, however in either case timing information in the data files are accurate and should be relied upon when processing the data. Electric Antenna Length ----------------------Originally Waves Survey electric field data were calibrated using an effective antenna length of 2.41 m based on the geometry of the deployed, physical antenna elements. Starting with release 14 (Sept. 2020) the effective antenna length was revised to 0.5 m and all previously released data product files were regenerated and re-released using the new value. The rationale for this revision is summarized below. In very simple terms, the Waves instrument measures the differential potential between the two elements of the electric antenna. The electric field E is simply: -V/Leff where V is the measured potential and Leff is the effective antenna length. The pre-launch calibration utilized the geometric antenna length which is basically the distance between the mid-points of the two conducting antenna elements, 2.41 m. The second revision calibration modifies this length by two important electrical considerations. These are discussed in detail by Kurth et al. (2017) https://doi.org/10.1007/s11214-017-0396-y, but the first involves taking the complex and large surrounding spacecraft structure, including the solar panels, into account. This structure is the ground plane for the antenna system. Given the very short antenna elements (2.8 m) in the presence of the spacecraft with ~ 8-m solar panels and associated structure, the spacecraft effectively decreases the effective length of the antenna system. This effect was studied by Sampl et al. (2012; 2016) https://doi.org/10.1002/2016RS005954, using both an analog rheometry analysis as well as a surface patch model of the spacecraft. The result is that the antenna has an effective length, after taking into account the complex ground plane of the spacecraft of 1.46 m. The second effect is a capacitive divider effect due to the base capacitance of the antenna and the capacitance of the antenna to space. While the base capacitance is somewhat uncertain, this is effectively a decrease in sensitivity (equivalently, another decrease in effective length) of 8 db. Combining these, we've used an effective antenna length of 0.5 meters for the Juno electric antenna in the second revision calibration tables. Clearly, this means the newly-calibrated electric field associated with a 1-V potential difference is 4.8 times greater than the old one. And, spectral densities that are proportional to E**2 will increase by a factor of about 23.

Processing

Data products for this data set were generated by the CDR data production pipeline as described in section 3 of the VOLSIS document found under the DOCUMENTS sub-directory. The inputs to the processing are: 1. Science and Housekeeping packets from the Waves Level 2 data set. 2. Calibration tables located on this volume. 3. NAIF Juno mission SPICE kernels. 4. A listing of mission phase names and orbit number by UTC. The result of the processing is one spreadsheet file per frequency band per day in which data are available. The WAVES_CAL document in the DOCUMENT directory provides details of the calibration process. These data are calibrated using the best calibration tables and algorithms available at the time the data were archived. Should a significant improvement in calibration become available, an erratum will be noted in the erratum section. Later versions of the products may contain better calibrations.

Data

The Waves calibrated full resolution survey mode data set includes five ASCII spreadsheets of wave spectra as a function of time from both the upper and lower band of the LFR, the lower band of the HFR as well as the upper spectrum analyzer bands of the HFR. Each spreadsheet contains a fixed number of fields containing the measurement initiation times by spacecraft clock and UTC, a flag to indicate the employment of on-board noise mitigation techniques, a flag to indicate whether the row is a science measurement or a noise sample spectra, and a flag to indicate the presence of burst mode data near the given measurement time, as well as one field for each frequency bin. Typically electric measurements from 50 Hz to 150 kHz and magnetic measurements from 20 kHz to 20 kHz are measured simultaneously, however this is not always the case. Waves has the ability to sample solar panel switching noise and to mitigate this noise to a limited extent. When operating in this mode it is not possible to collect all data below 150 kHz simultaneously. In these instances time tags on the magnetic data will not line up with time tags on the corresponding electric data, however regardless of the operating mode timing information in the data files is accurate and should be relied upon when processing these data instead of assuming any particular time correspondence between receiver bands and sensors.

Ancillary Data

Ancillary data included with the data set collection include a series of files that describe the Waves operating modes as a function of time and provide a time-ordered listing of the Instrument Expanded Block (IEB) trigger commands (WAV_MAJOR_MODE) (the mode by which Waves is reconfigured). Also a detailed description of each of the modes (or IEBs) is provided. Other data which are ancillary to this data set, but which are archived separately from this collection are the Navigation and Ancillary Information Facility's SPICE kernels describing the position and attitude of Juno and various solar system bodies as a function of time.

Coordinate Systems

The data in this data set are measurements of wave electric and magnetic field spectral densities measured by the Waves electric and magnetic sensors. These fields are presented as detected by the sensors and are not rotated into any other coordinate system. If desired the SPICE kernels can be used with the SPICE toolkit to convert from the spacecraft frame to virtually any frame which may be of use in analyzing these data. However, for many purposes, because of the broad beam of the dipole-like sensors, the spectral densities are extremely useful and may be entirely adequate with no coordinate transformations at all.

Software

As these data are calibrated and in simple ASCII form, no software is provided, and none is required, for conversion or interpretation. However the EXTRAS/SOFTWARE directory does contain the viewing tool used to generate the BROWSE directory spectrograms. This tool may be used to 'zoom in' on regions of interest and to view burst mode data when available.

Media/Format

This data set is provided to the Planetary Data System electronically as part of a volume level 'tarball' file, though the standards for file names, directory names and path lengths follow the guidelines provided in the 'Planetary Data System Standards Reference', version 3.8, under section 10.1.3, 'Specification for Files Delivered Electronically'. The 'tarball' file contains all files for a release of this volume in a single GNU Tar file that has then been compressed via the GNU gzip utility. The tar file preserves the relative directory path for each file so when unpacked the original volume directory structure is recreated. See Section 4 of the VOLSIS for more details on the data transfer methods. The primary data products are comma separated values (CSV) files. Since this is a survey product, an attempt has been made to group a single sweep of all frequency ranges routinely covered by the instrument into single rows in the product data files. In actuality every receiver section may be scheduled independently of the others and there are operational modes where it is not possible to include measurements from all frequencies with a single row in the product files. At Apoapsis Cadence (1 sweep/30 seconds), or Intermediate Cadence (1 sweep/10 seconds), one row in the product data files typically contains an amplitude measurement for each frequency. However when operating in one of the Periapsis Cadence modes (~1 sweep/second) certain instrument bands will only be sampled once for every two times a higher frequency band is covered. In these cases a single row in the data product files may have many empty entries. This is normal and reflects the original collection scheduling. It is not a transmission error nor a processing error.

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

https://pds-ppi.igpp.ucla.edu/data/JNO-E_J_SS-WAV-3-CDR-SRVFULL-V2.0/

Alternate Names

  • JNO-E/J/SS-WAV-3-CDR-SRVFULL-V2.0

Discipline

  • Planetary Science: Fields and Particles

Additional Information

Spacecraft

Experiments

Questions and comments about this data collection can be directed to: Dr. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. William S. KurthGeneral ContactUniversity of Iowawsk@space.physics.uiowa.edu
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