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IMAGE RPI Dynamic Spectrogram data in CDF at NASA CDAWeb

ResourceID
spase://NASA/NumericalData/IMAGE/RPI/DS/PT5M

Description

RPI passive wave measurement capturing voltage spectral density of the radio emissions in space as a function of frequency, typically between 3 and 1009 kHz. This operating frequency range was selected by the RPI team to provide optimal temporal resolution of the wave observations. Commonly used in the analysis of noise generators, spectral density is a frequency-dependent characteristic that describes how much power is generated by the emission source in a 1 Hz bandwidth. The original description of emissions was done in terms of thermal noise measurements, though the same approach also applies to non-thermal emissions such as AKR. CDF_DS_PT5M stores calibrated data from all three RPI antennas X, Y, and Z individually and a combined X+Y antenna channel. The data are presented as the Voltage Spectral Density (VSD), which is the root of power spectral density, measured in [V/root-Hz] units. Note that conversion of antenna voltage to electric field strength depends on the effective length of the receive antenna, and such conversion is not performed here. (See spase://SMWG/Instrument/IMAGE/RPI for a time history of the lengths of the three mutually orthogonal RPI dipole antennas.) RPI is capable of detecting input radio emissions above its noise floor of 5 nV/root-Hz, which is determined by the internal white noise of the RPI antenna pre-amplifiers. The VSD in RPI spectrogram data is presented in dB relative to 1 V/root-Hz (logarithmic scale), units of dB(V/root-Hz). The RPI instrument noise floor is 5 nV/root-Hz = -166 dB(V/root-Hz) at the receiver input. Software suggested by the science team for CDF file visualization: (1) Plotting tool at the CDAWeb portal, (2) For analysis beyond static image inspection, including color scale optimization, zooming, text export, alternative data representations in physical units, detailed frequency and time information, overlaid model fpe and fce graphs, and EPS quality figures, use BinBrowser software at UML, http://ulcar.uml.edu/rpi.html

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NumericalData

ResourceID
spase://NASA/NumericalData/IMAGE/RPI/DS/PT5M
ResourceHeader
ResourceName
IMAGE RPI Dynamic Spectrogram data in CDF at NASA CDAWeb
AlternateName
IM_K1_RPI
ReleaseDate
2020-07-07 21:14:38Z
Description

RPI passive wave measurement capturing voltage spectral density of the radio emissions in space as a function of frequency, typically between 3 and 1009 kHz. This operating frequency range was selected by the RPI team to provide optimal temporal resolution of the wave observations. Commonly used in the analysis of noise generators, spectral density is a frequency-dependent characteristic that describes how much power is generated by the emission source in a 1 Hz bandwidth. The original description of emissions was done in terms of thermal noise measurements, though the same approach also applies to non-thermal emissions such as AKR. CDF_DS_PT5M stores calibrated data from all three RPI antennas X, Y, and Z individually and a combined X+Y antenna channel. The data are presented as the Voltage Spectral Density (VSD), which is the root of power spectral density, measured in [V/root-Hz] units. Note that conversion of antenna voltage to electric field strength depends on the effective length of the receive antenna, and such conversion is not performed here. (See spase://SMWG/Instrument/IMAGE/RPI for a time history of the lengths of the three mutually orthogonal RPI dipole antennas.) RPI is capable of detecting input radio emissions above its noise floor of 5 nV/root-Hz, which is determined by the internal white noise of the RPI antenna pre-amplifiers. The VSD in RPI spectrogram data is presented in dB relative to 1 V/root-Hz (logarithmic scale), units of dB(V/root-Hz). The RPI instrument noise floor is 5 nV/root-Hz = -166 dB(V/root-Hz) at the receiver input. Software suggested by the science team for CDF file visualization: (1) Plotting tool at the CDAWeb portal, (2) For analysis beyond static image inspection, including color scale optimization, zooming, text export, alternative data representations in physical units, detailed frequency and time information, overlaid model fpe and fce graphs, and EPS quality figures, use BinBrowser software at UML, http://ulcar.uml.edu/rpi.html

Acknowledgement
Users please acknowledge Coordinated Data Analysis Web (CDAWeb) at the NASA Goddard Space Flight Center and RPI Principal Investigator Prof. B. W. Reinisch of the University of Massachusetts Lowell for making these CDF files available.
Contacts
RolePerson
1.PrincipalInvestigatorspase://SMWG/Person/Bodo.W.Reinisch
2.DataProducerspase://SMWG/Person/Ivan.A.Galkin
InformationURL
Name
IMAGE RPI Instrument Page
URL
https://image.gsfc.nasa.gov/rpi/
Description

IMAGE RPI Instrument page maintained by NASA GSFC with RPI facts, description, team, data, documents, discoveries, and related links sections

Language
en
InformationURL
Name
IMAGE RPI Instrument Page at UML
URL
https://ulcar.uml.edu/rpi.html
Description

IMAGE RPI Instrument page maintained by University of Massachusetts Lowell with RPI description, team, software downloads, software user guides, access to CORPRAL automated prospecting results, mission planning tools and commanding guide, data model descriptions for Level 0 and 1, sonification files of 2003 Halloween storm, and useful links

Language
en
InformationURL
Name
IMAGE RPIAnywhere Download Page
URL
https://ulcar.uml.edu/Installation/install_all.htm
Description

RPIAnywhere software download page, including BinBrowser (RPI data analysis tool) and EdRPI (RPI mission planning tool)

Language
en
Association
AssociationID
spase://NASA/DisplayData/IMAGE/RPI/DS/P1D
AssociationType
DerivedFrom
PriorIDs
spase://VWO/NumericalData/IMAGE/RPI/CDF_DS_PT5M
spase://VWO/NumericalData/IMAGE/RPI/DS.PT5M
spase://VSPO/NumericalData/IMAGE/RPI/DS.PT5M
spase://VSPO/NumericalData/IMAGE/RPI/DS/PT5M
AccessInformation
RepositoryID
spase://SMWG/Repository/NASA/GSFC/SPDF
Availability
Online
AccessRights
Open
AccessURL
Name
FTPS from SPDF (not with most browsers)
URL
ftps://spdf.gsfc.nasa.gov/pub/data/image/rpi/rpi_k1/
Description

FTP access to repository of IMAGE RPI passive wave measurements (dynamic spectrograms) in CDF format at NASA CDAWeb.

Language
en
AccessURL
Name
HTTPS from SPDF
URL
https://spdf.gsfc.nasa.gov/pub/data/image/rpi/rpi_k1/
Description

http access to repository of IMAGE RPI passive wave measurements (dynamic spectrograms) in CDF format at NASA CDAWeb.

Language
en
AccessURL
Name
CDAWeb
URL
https://cdaweb.sci.gsfc.nasa.gov/cgi-bin/eval2.cgi?dataset=IM_K1_RPI&index=sp_phys
ProductKey
IM_K1_RPI
Description

Access to ASCII, CDF, and plots via NASA/GSFC CDAWeb

Format
CDF
Encoding
None
DataExtent
Quantity
9449
Units
MByte
Acknowledgement
Users please acknowledge Coordinated Data Analysis Web (CDAWeb) at the NASA Goddard Space Flight Center and RPI Principal Investigator Prof. B. W. Reinisch of the University of Massachusetts Lowell for making these CDF files available.
ProcessingLevel
Calibrated
ProviderProcessingLevel
Calibrated data in physical units. Spacecraft MET to UT is converted using history of IMAGE observatory clock drift. Added data items: Combined XY channel VSD value is obtained as the length of a vector formed by X and Y channel VSD components; spacecraft spin modulation is not seen in XY channel data. Data reduction from full resolution telemetry dataset to this Level-1 dataset: (1) Selection of one sample out of 8 available in TTD databin, (2) removal of cross-phase and cross-power terms available in TTD databin.
InstrumentIDs
spase://SMWG/Instrument/IMAGE/RPI
MeasurementType
Waves.Passive
MeasurementType
Spectrum
MeasurementType
ElectricField
TemporalDescription
TimeSpan
StartDate
2000-04-21 20:24:42Z
StopDate
2005-12-18 07:50:00Z
Note
In Cadence below, the 5 minutes refers to the nominal interval between measurements. Actual cadence of passive measurement varied between 3 to 6 minutes depending on the RPI science plan and design of measurement schedules.
Cadence
PT5M
Exposure
PT72S
SpectralRange
RadioFrequency
ObservedRegion
Earth.Magnetosphere
ObservedRegion
Earth.NearSurface.Plasmasphere
ObservedRegion
Earth.NearSurface.AuroralRegion
ObservedRegion
Earth.NearSurface.PolarCap
ObservedRegion
Heliosphere.Inner
Caveats
(A) Known artifacts of dynamic spectrograms are (1) a horizontal line at 20 kHz where the frequency stepping changes from linear to logarithmic, and (2) a variety of interference sources internal to the IMAGE observatory appear as horizontal lines on the dynamic spectrograms including, most prominently, 101 kHz; additional lines appear at 63 kHz and its 126 kHz 2nd harmonic (battery charger), at times a broad band is also present between 160 and 200 kHz due to the torque rod operation, and a narrow line appears at 75 kHz due to the S-band transponder. Other known intereferer lines are 150 kHz, 200 kHz, and 240 kHz (deck plate heaters and other onboard instruments), but these lines are usually not present in the measurement. (B) When the spectrogram is plotted, the pixel size is made wide enough to fill the gaps caused by the 5 minute cadence of the measurements. (C) Comparison of voltage spectral density with other space receiver data has to consider differences in the antenna configurations.
Keywords
Dynamic Spectrogram
Spectrogram
AKR
Auroral hiss
Auroral Kilometric Radiation
Chorus
Continuum radiation
Myriametric radiation
Plasmaspheric Hiss
Solar radio burst
Terrestrial Kilometric Radiation
TKR
Type II Solar radio burst
Type III Solar radio burst
UHR
Upper hybrid resonance
VLF Station
VLF Transmitter
Whistler
Parameter #1
Name
Voltage spectral density
Description

Commonly used in circuit analysis, Power Spectral Density (PSD) describes how much noise power is generated by the emission source in a 1 Hz bandwidth. Dynamic Specrtograms use Voltage Spectral Density (VSD), which is root of PSD, measured in V/root-Hz units. The VSD in RPI spectrograms is presented in dB relative to 1 V/root-Hz (logarithmic scale), units of dB(V/root-Hz). On average, the RPI instrument noise floor is 5 nV/root-Hz = -166 dB(V/root-Hz) at the receiver input.

Cadence
PT5M
Units
dB(V/root-Hz)
RenderingHints
DisplayType
Spectrogram
AxisLabel
Frequency, kHz
RenderingAxis
Vertical
Index
-1 0
ValueFormat
I4
ScaleMin
3
ScaleMax
1100
ScaleType
LogScale
RenderingHints
DisplayType
Spectrogram
AxisLabel
Universal Time
RenderingAxis
Horizontal
RenderingHints
DisplayType
Spectrogram
AxisLabel
X Amplitude, dB(V/root-Hz)
RenderingAxis
ColorBar
Index
0 1
ValueFormat
I4
ScaleMin
-144
ScaleMax
-96
ScaleType
LinearScale
RenderingHints
DisplayType
Spectrogram
AxisLabel
Y Amplitude, dB(V/root-Hz)
RenderingAxis
ColorBar
Index
0 2
ValueFormat
I4
ScaleMin
-144
ScaleMax
-96
ScaleType
LinearScale
RenderingHints
DisplayType
Spectrogram
AxisLabel
Z Amplitude, dB(V/root-Hz)
RenderingAxis
ColorBar
Index
0 3
ValueFormat
I4
ScaleMin
-144
ScaleMax
-96
ScaleType
LinearScale
RenderingHints
DisplayType
Spectrogram
AxisLabel
XY Amplitude, dB(V/root-Hz)
RenderingAxis
ColorBar
Index
0 4
ValueFormat
I4
ScaleMin
-144
ScaleMax
-96
ScaleType
LinearScale
Structure
Size
256 4
Description

One measurement is an array of voltage spectral density (VSD) values, as functions of frequency, obtained during the frequency sweep. For each operating frequency, four values of VSD are reported: (1) antenna X, (2) antenna Y, (3) antenna Z, (4) combined antennas X and Y to remove spacecraft spin modulation. Resulting structure is a linear 256 x 4 array. Number of frequencies for which the voltage spectral density values are given depends on the choice of frequency sweep (see "List of Frequencies" and "Number of Frequencies" parameters and their description below). The "256" value stated in Size is the upper limit. Note that Index "0" means a wild card ("don't care" index "1" means the whole dimension.

Element
Name
Frequency Dimension
Index
-1 0
ParameterKey
Frequency
Element
Name
Antenna Dimension
Index
0 -1
Element
Name
Voltage Spectral Density in antenna X
Index
0 1
ParameterKey
Amplitude_X
Units
dB(V/root-Hz)
ValidMin
-190
ValidMax
-70
FillValue
-1.0e+031
Element
Name
Voltage Spectral Density in antenna Y
Index
0 2
ParameterKey
Amplitude_Y
Units
dB(V/root-Hz)
ValidMin
-190
ValidMax
-70
FillValue
-1.0e+031
Element
Name
Voltage Spectral Density in antenna Z
Index
0 3
ParameterKey
Amplitude_Z
Units
dB(V/root-Hz)
ValidMin
-190
ValidMax
-70
FillValue
-1.0e+031
Element
Name
Voltage Spectral Density in combined antennas X and Y
Index
0 4
ParameterKey
Amplitude_XY
Units
dB(V/root-Hz)
ValidMin
-190
ValidMax
-70
FillValue
-1.0e+031
Wave
WaveType
PlasmaWaves
Qualifier
Magnitude
Qualifier
Spectral
Qualifier
Pseudo
WaveQuantity
Intensity
FrequencyRange
SpectralRange
RadioFrequency
Low
3
High
1009
Units
kHz
Parameter #2
Name
List of Frequencies
ParameterKey
Frequency
Description

List of operating frequencies at which sample data were collected to obtain VSD values. Actual frequency values vary from measurement to measurement depending on the choice of frequency sweep. Early in the mission, a variety of frequency sweeps were tested until March 27, 2001 when they were streamlined to three basic types: PROGRAM-23: linear sweep from 3 to 20 kHz with 400 Hz step (13 sec running time), PROGRAM-26: logarithmic sweep from 20 to 1009 kHz with 2% stepping (59 sec running time), and PROGRAM-25: logarithmic sweep from 20 to 300 kHz with 2% stepping (37 sec running time). Most commonly used since April 2001, PROGRAM-23 and PROGRAM-26 combination takes 72 sec to complete one sweep from 3 to 1009 kHz. Other frequency sweeps were also exercised, in addition to the three basic types, during experiments on detection of signals from the ground VLF transmitters. For a greater detail on the RPI measurement programming cases in the dynamic spectrogram mode, please refer to RPI operational logs available as part of the RPIAnywhere software package at http://ulcar.uml.edu/rpi.html.

Cadence
PT5M
Units
kHz
Structure
Size
256
Description

Linear 1D array of frequency values, up to 256. Actual number of frequencies for which the voltage spectral density values were measured depends on the choice of frequency sweep (see "Number of Frequencies" parameter and its description below). The "256" value stated in Size is the upper limit.

Element
Name
Frequency
Index
-1
ValidMin
3
ValidMax
3000
FillValue
-1.0e+031
Support
SupportQuantity
Other
Parameter #3
Name
Number of Frequencies
ParameterKey
NumFreqs
Description

Number of frequencies in the sweep, see "List of Frequencies

ValidMin
0
ValidMax
256
FillValue
-32768
Support
SupportQuantity
Other
Parameter #4
Name
Start Time
ParameterKey
Epoch
Description

Epoch timestamp of the beginning of the spectrogram measurement. Use Measurement Duration to obtain time of measurement stop.

Caveats
The 5 minutes refers to the nominal interval between measurements. Actual cadence of passive measurement varied between 3 to 6 minutes depending on the RPI science plan and design of measurement schedules.
Cadence
PT5M
Units
ms
Support
SupportQuantity
Temporal
Parameter #5
Name
Measurement Duration
ParameterKey
Duration_ms
Description

Duration of one spectrogram measurement.

Units
ms
Support
SupportQuantity
Temporal
Parameter #6
Name
Number of Repetitions
ParameterKey
NumRepetitions
Description

Number of looks at each of the spectrogram frequencies, encoded. Encoding: stored number N is used as power of 2 (i.e., 2**N is actual number of repetitions)

ValidMin
3
ValidMax
8
FillValue
-128
Support
SupportQuantity
Other
Parameter #7
Name
Base Gain
ParameterKey
BaseGain
Description

Instrument setting describing receiver gains in X/Y and Z channels, encoded. See data model description at http://ulcar.uml.edu/rpi.html for additional details on base gain decoding procedure.

ValidMin
0
ValidMax
16
FillValue
255
Support
SupportQuantity
Other
Parameter #8
Name
Measurement Program Specification
ParameterKey
ProgramSpecs
Description

List of 25 parameter values that specify RPI instrument configuration during the measurement. For further detail on parameter value interpretation see data model description document at http://ulcar.uml.edu/rpi.html.

Cadence
PT5M
Structure
Size
25
Description

Linear 1D array of values used to configure RPI instrument for a measurement mode.

Element
Name
RPI Parameter
Index
-1
Support
SupportQuantity
Other