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Data Access
FTPS from SPDF (not with most browsers)
HTTPS from SPDF
Subset, plot, list from CDAWeb
Ahmedabad, India
Ascension Island, United Kingdom
Brazzavillle, Congo
Fairbanks, Alaska
Falkland Island, United Kingdom
Johannesburg, South Africa
Kashima, Japan
Kerguelen Island, France
Kourou, French Guyana
Kwajalein, Marshall Islands
Las Palmas, Canary Island, Spain
Lauder, New Zealand
Orroral, Australia
Ottawa, QC, Canada
Ouagadougou, Burkina Faso
Quito, Equador
Resolute Bay, NU, Canada
Santiago, Chile
Syowa Base, Antartica
Sodankyla, Finland
Terre Adelie, Antarctica
Tromso, Norway
Winkfield, United Kingdom
ISIS 2 Topside Sounder Ionograms
var authors='Whitteker, James H.';
document.write(authors);
(2025).
ISIS 2 Topside Sounder Ionograms.
[Data set].
Space Physics Data Facility.
https://doi.org/10.48322/v11k-e045. Accessed on document.write(currentDateStr);.
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ResourceID
spase://NASA/NumericalData/ISIS2/SFS/Ionogram/PT22S
Description
These ionograms were digitized from the original ISIS-2 7-track analog telemetry tapes using the facilities of the former Data Evaluation Laboratory at the NASA/GSFC. This data restoration project is headed by Dr. R.F. Benson (NASA/GSFC). Ionograms were digitized at the rate of 40,000 16-bit samples/sec. This sample rate is higher than the Nyquist frequency of 30 kHz. The sample frequency of 40 kHz provides a measurement every 25 microseconds corresponding to an apparent range (c*t/2) interval of 3.75 km. Ionograms with this sample rate are designated as "full" ionograms because they have the full 3.75 km apparent-range resolution. The ionograms used for most analysis, and those available from CDAWeb, were produced by averaging every four samples of the sounder-receiver video amplitude output to yield an average value every 100 microseconds corresponding to an apparent-range resolution of 15 km. These ionogram files are referred to as "average" files with standard resolution. Each ionogram consists of a fixed-frequency and and a swept-frequency portion. The time resolution between ionograms is typically 14 or 22 seconds depending on the frequency sweep range.
Metadata Rights
CC0-1.0:
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available SPASE metadata descriptions. The actual data/software may be subject to a different license.
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Version:2.7.1
NumericalData
ResourceID
spase://NASA/NumericalData/ISIS2/SFS/Ionogram/PT22S
NamingAuthority
NASA
ResourceType
NumericalData
ResourceHeader
ResourceName
ISIS 2 Topside Sounder Ionograms
AlternateName
ISIS-2 Topside Sounder Ionogram CDFs at NASA's CDAWeb
DOI
https://doi.org/10.48322/v11k-e045
ReleaseDate
2026-02-12 23:08:33Z
RevisionHistory
RevisionEvent
ReleaseDate
2020-07-07 21:14:43Z
Note
Only known prior ReleaseDate of the metadata
RevisionEvent
ReleaseDate
2025-11-14 16:02:30Z
Note
Added PublicationInfo. Added ResourceType and NamingAuthority. Changed http to https in top-level schemaLocation attribute. Fixed version number separator in top-level schemaLocation attribute. Matched version number in schemaLocation attribute to updated value in Version tag. ZCB
RevisionEvent
ReleaseDate
2025-12-04 13:29:44Z
Note
Added MetadataRightsList and RightsList(s). Updated to 2.7.1. ZCB
RevisionEvent
ReleaseDate
2026-02-12 23:08:33Z
Note
Added DOI. tlk
Description
These ionograms were digitized from the original ISIS-2 7-track analog telemetry tapes using the facilities of the former Data Evaluation Laboratory at the NASA/GSFC. This data restoration project is headed by Dr. R.F. Benson (NASA/GSFC). Ionograms were digitized at the rate of 40,000 16-bit samples/sec. This sample rate is higher than the Nyquist frequency of 30 kHz. The sample frequency of 40 kHz provides a measurement every 25 microseconds corresponding to an apparent range (c*t/2) interval of 3.75 km. Ionograms with this sample rate are designated as "full" ionograms because they have the full 3.75 km apparent-range resolution. The ionograms used for most analysis, and those available from CDAWeb, were produced by averaging every four samples of the sounder-receiver video amplitude output to yield an average value every 100 microseconds corresponding to an apparent-range resolution of 15 km. These ionogram files are referred to as "average" files with standard resolution. Each ionogram consists of a fixed-frequency and and a swept-frequency portion. The time resolution between ionograms is typically 14 or 22 seconds depending on the frequency sweep range.
Acknowledgement
Users please acknowledge the Coordinated Data Analysis Web (CDAWeb) at the NASA Goddard Space Flight Center, ISIS-2 SFS instrument Principal Investigator J. H. Whitteker and ISIS Data-Restoration project lead Robert F. Benson.
PublicationInfo
Authors
Whitteker, James H.
PublicationDate
2025-11-14 16:02:30Z
PublishedBy
Space Physics Data Facility
Contacts
Role
Person
StartDate
StopDate
Note
1.
PrincipalInvestigator
spase://SMWG/Person/James.H.Whitteker
2.
GeneralContact
spase://SMWG/Person/Robert.F.Benson
3.
GeneralContact
spase://SMWG/Person/Dieter.K.Bilitza
InformationURL
Name
ISIS/Alouette Topside Sounder Data Restoration Project
URL
https://nssdc.gsfc.nasa.gov/space/isis/isis-status.html
Description
ISIS/Alouette page maintained by NASA GSFC with science and instrument descriptions, data access, software, and publication lists
Language
en
InformationURL
Name
NSSDC's Master Catalog
URL
https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1971-024A-01
Description
Information about the Sweep Frequency Sounder experiment on ISIS-2.
PriorIDs
spase://VWO/NumericalData/ISIS2/SFS/ISIS2_Ionogram_CDF_PT22S
spase://VWO/NumericalData/ISIS2/SFS/Ionogram.PT22S
spase://VSPO/NumericalData/ISIS2/SFS/Ionogram/PT22S
AccessInformation
RepositoryID
spase://SMWG/Repository/NASA/GSFC/SPDF
Availability
Online
AccessRights
Open
RightsList
Rights
SchemeURI
https://spdx.org/licenses/
RightsIdentifierScheme
SPDX
RightsIdentifier
CC0-1.0
RightsURI
https://spdx.org/licenses/CC0-1.0.html
RightsName
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available NASA Heliophysics data products
AccessURL
Name
FTPS from SPDF (not with most browsers)
URL
ftps://spdf.gsfc.nasa.gov/pub/data/isis/topside_sounder/ionogram_cdf/isis2/
Description
FTP access to repository of ISIS-2 Ionograms in CDF format at NASA CDAWeb. The CDF files are organized by ground station, where each ground station is represented by a three letter ID and a two-digit code. The full names for each station are provided at https://nssdc.gsfc.nasa.gov/space/isis/isis-table1-new.html A merged data set, independent of the ground stations, is planned.
Language
en
AccessURL
Name
HTTPS from SPDF
URL
https://spdf.gsfc.nasa.gov/pub/data/isis/topside_sounder/ionogram_cdf/isis2/
Description
HTTPS access to repository of ISIS-2 Ionograms in CDF format at NASA CDAWeb
Language
en
AccessURL
Name
Subset, plot, list from CDAWeb
URL
https://cdaweb.gsfc.nasa.gov/sp_phys/
Description
CDAWeb interactive interface for subsets, plots and lists of data
AccessURL
Name
Ahmedabad, India
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Ahmedabad/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Ahmedabad, India: AME, Latitude 23, Longitude 73
AccessURL
Name
Ascension Island, United Kingdom
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/AscensionIsland/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Ascension Island, United Kingdom: ACN, Latitude -8, Longitude 346
AccessURL
Name
Brazzavillle, Congo
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Brazzaville/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Brazzavillle, Congo: BRZ, Latitude -4, Longitude 15
AccessURL
Name
Fairbanks, Alaska
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Fairbanks/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Fairbanks, AK: ULA, Latitude 65, Longitude 212
AccessURL
Name
Falkland Island, United Kingdom
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/FalklandIslands/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Falkland Island, United Kingdom: SOL, Latitude -52, Longitude 302
AccessURL
Name
Johannesburg, South Africa
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Johannesburg/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Johannesburg, South Africa: BUR, Latitude -26, Longitude 28
AccessURL
Name
Kashima, Japan
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Kashima/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Kashima, Japan: KSH, Latitude 36, Longitude 141
AccessURL
Name
Kerguelen Island, France
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/KerguelenIsland/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Kerguelen Island, France: KER, Latitude -49, Longitude 70
AccessURL
Name
Kourou, French Guyana
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Kourou/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Kourou, French Guyana: KRU, Latitude 5, Longitude 307
AccessURL
Name
Kwajalein, Marshall Islands
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Kwajalein/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Kwajalein, Marshall Islands: KWA, Latitude 9, Longitude 168
AccessURL
Name
Las Palmas, Canary Island, Spain
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/LasPalmas/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Las Palmas, Canary Island, Spain: CNA, Latitude 28, Longitude 345
AccessURL
Name
Lauder, New Zealand
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Lauder/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Lauder, New Zealand: LAU, Latitude -45, Longitude 170
AccessURL
Name
Orroral, Australia
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Orroral/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Orroral, Australia: ORR, Latitude -36, Longitude 149
AccessURL
Name
Ottawa, QC, Canada
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Ottawa/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Ottawa, QC, Canada: OTT, Latitude 45, Longitude 284
AccessURL
Name
Ouagadougou, Burkina Faso
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Ouagadougou/PT22S
Description
ISIS-1 Topside Sounder Average Ionogram over Ouagadougou, Burkina Faso: ODG, Latitude 14, Longitude 359
AccessURL
Name
Quito, Equador
URL
https://hpde.io/NASA/NumericalData/ISIS1/SFS/AverageIonogram/Quito/PT29S
Description
ISIS-2 Topside Sounder Average Ionogram over Quito, Equador: QUI, Latitude -1, Longitude 281
AccessURL
Name
Resolute Bay, NU, Canada
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/ResoluteBay/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Resolute Bay, NU, Canada: RES, Latitude 75, Longitude 265
AccessURL
Name
Santiago, Chile
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Santiago/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Santiago, Chile: SNT, Latitude -33, Longitude 298
AccessURL
Name
Syowa Base, Antartica
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Sodankyla/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Syowa Base, Antartica: SYO, Latitude -69, Longitude 40
AccessURL
Name
Sodankyla, Finland
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/SyowaBase/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Sodankyla, Finland: SOD, Latitude 67, Longitude 27
AccessURL
Name
Terre Adelie, Antarctica
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/TerreAdelie/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Terre Adelie, Antarctica: ADL, Latitude -67, Longitude 140
AccessURL
Name
Tromso, Norway
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Tromso/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Tromso, Norway: TRO, Latitude 70, Longitude 19
AccessURL
Name
Winkfield, United Kingdom
URL
https://hpde.io/NASA/NumericalData/ISIS2/SFS/AverageIonogram/Winkfield/PT22S
Description
ISIS-2 Topside Sounder Average Ionogram over Winkfield, United Kingdom: WNK, Latitude 51, Longitude 359
Format
CDF
Encoding
None
Acknowledgement
Please acknowledge the CDAWeb team at NASA/GSFC/SPDF
ProcessingLevel
Calibrated
InstrumentIDs
spase://SMWG/Instrument/ISIS2/SFS
MeasurementType
Waves.Active
MeasurementType
Spectrum
TemporalDescription
TimeSpan
StartDate
1969-01-30 14:50:12Z
StopDate
1983-12-30 15:19:33Z
Note
Note: The cadence is 14 or 22.5 s for ionograms that have a swept-frequency portion from 0.1 to 10.0 MHz and 0.1 to 20 MHz, respectively.
Cadence
PT22S
SpectralRange
RadioFrequency
ObservedRegion
Earth.Magnetosphere
ObservedRegion
Earth.Magnetosphere.Polar
ObservedRegion
Earth.NearSurface.AuroralRegion
ObservedRegion
Earth.NearSurface.PolarCap
ObservedRegion
Earth.NearSurface.Ionosphere
ObservedRegion
Earth.NearSurface.Ionosphere.Topside
Caveats
See discussion on "How To Detect Erroneous ISIS-2 Digital Ionogram Files" at https://nssdc.gsfc.nasa.gov/space/isis/isis_read_error.html
Keywords
Ionogram
topside sounder
fixed- and swept-frequency sounder
topside ionosphere
ionospheric reflections
ground reflections
ionospheric echoes
ground echoes
ducted echoes
wave scattering
field-aligned irregularities
FAI
plasma resonance
plasma waves
AKR
solar type III bursts
upper-hybrid noise band
Parameter #1
Name
satellite ID
ParameterKey
satellite
Description
sat.-ID: 1=AL1, 2=AL2, 3=ISIS1, 4=ISIS2
Support
SupportQuantity
Other
Parameter #2
Name
telemetry station code
ParameterKey
station_id
Description
two-digit telemetry station code
Support
SupportQuantity
Other
Parameter #3
Name
transmitter power code
ParameterKey
power_code
Description
trans. power code: 1=Prim(400W) 2=Sec(400W)
Support
SupportQuantity
Other
Parameter #4
Name
sounder/receiver code
ParameterKey
s/r_code
Description
sounder/receiver code: 0=off, 1=on
Support
SupportQuantity
Other
Parameter #5
Name
swept frequency range code
ParameterKey
f_range_code
Description
swept-f range code: 0=normal (swept-frequency from 0.1 to 10.0 MHz), 1=extended (swept-frequency from 0.1 to 20.0 MHz)
Support
SupportQuantity
Other
Parameter #6
Name
DMODE code
ParameterKey
DMODE
Description
DMODE (transm. on/off for alternate frame pairs): 0=off, 1=on
Support
SupportQuantity
Other
Parameter #7
Name
GMODE code
ParameterKey
GMODE
Description
GMODE (transmission of alternate frames of fixed-frequency ionograms and normal combined fixed- and swept-frequency ionograms): 0=off, 1=on
Support
SupportQuantity
Other
Parameter #8
Name
sounder mixed mode
ParameterKey
mixed_mode
Description
sounder mixed mode (transmission at a fixed-frequency while the sounder receiver sweeps over swept-frequency range): 0=off, 1=on
Support
SupportQuantity
Other
Parameter #9
Name
AIT mode
ParameterKey
AIT_mode
Description
AIT mode (automatic sounder operation every 3 min): 0=off, 1=on
Support
SupportQuantity
Other
Parameter #10
Name
fixed frequency code (0-6)
ParameterKey
fix_freq
Description
fixed frequency code: 0=off, 1=0.12, 2=0.48, 3=1.00, 4=1.95, 5=4.00, 6=9.303 MHz
Support
SupportQuantity
Other
Parameter #11
Name
Year
ParameterKey
year
Description
Year of ionogram frame sync in UT
Support
SupportQuantity
Other
Parameter #12
Name
Day of Year
ParameterKey
doy
Description
Day of Year of ionogram frame sync in UT
Support
SupportQuantity
Other
Parameter #13
Name
Hour
ParameterKey
hr
Description
Hour of ionogram frame sync in UT
Support
SupportQuantity
Other
Parameter #14
Name
Minute
ParameterKey
min
Description
Minute of hour of ionogram frame sync in UT
Support
SupportQuantity
Other
Parameter #15
Name
Second
ParameterKey
sec
Description
Second of minute of ionogram frame sync in UT
Support
SupportQuantity
Other
Parameter #16
Name
Local Mean Time (hh,mm)
ParameterKey
LMT
Description
Local Mean Time (hh,mm) at time of ionogram frame sync
Structure
Size
2
Element
Name
LMT(hh)
Index
1
Units
hrs
Element
Name
LMT(mm)
Index
2
Units
min
Support
SupportQuantity
Other
Parameter #17
Name
geog coord (Lat,Long,Hgt)
ParameterKey
geo_coord
Description
geographic coordinates (Lat,Long,Hgt) at time of ionogram frame sync
Structure
Size
2
Element
Name
latitude
Index
1
Units
deg
Element
Name
longitude
Index
2
Units
deg
Element
Name
height
Index
3
Units
km
Support
SupportQuantity
Positional
Parameter #18
Name
Geomagnetic Local Time (hh,mm)
ParameterKey
GMLMT
Description
Geomagnetic Local Time (HHMM) at time of ionogram frame sync
Structure
Size
2
Element
Name
GMLMT(hh)
Index
1
Element
Name
GMLMT(mm)
Index
2
Support
SupportQuantity
Other
Parameter #19
Name
geom latitude
ParameterKey
GMLAT
Description
geomagnetic latitude at time of ionogram frame sync
Units
deg
Support
SupportQuantity
Positional
Parameter #20
Name
geom longitude
ParameterKey
GMLONG
Description
geomagnetic longitude at time of ionogram frame sync
Units
deg
Support
SupportQuantity
Positional
Parameter #21
Name
inv latitude
ParameterKey
INV_LAT
Description
invariant latitude at time of ionogram frame sync
Units
deg
Support
SupportQuantity
Other
Parameter #22
Name
magnetic inclination
ParameterKey
DIP
Description
Dip angle of mag field direction at time of ionogram frame sync
Units
deg
Support
SupportQuantity
Other
Parameter #23
Name
Solar Zenith Angle
ParameterKey
CHI
Description
Solar Zenith Angle at time of ionogram frame sync
Units
deg
Support
SupportQuantity
Other
Parameter #24
Name
L shell (McIlwain parameter)
ParameterKey
L
Description
L shell (McIlwain parameter) at time of ionogram frame sync
Support
SupportQuantity
Positional
Parameter #25
Name
spacecraft in/out sunlight
ParameterKey
sun
Description
spacecraft in(=1)/out(=2) sunlight at time of ionogram frame sync
Support
SupportQuantity
Other
Parameter #26
Name
Cyl. Electrost. Probe
ParameterKey
CEP
Description
CEP instrument on(1)/off(0) status
Support
SupportQuantity
Other
Parameter #27
Name
0.05-30 kHz VLF receiver
ParameterKey
VLF
Description
VLF receiver on(1)/off(0) status
Support
SupportQuantity
Other
Parameter #28
Name
Retarding Potential Analyzer
ParameterKey
RPA
Description
RPA instrument on(1)/off(0) status
Support
SupportQuantity
Other
Parameter #29
Name
Ion Mass Spectrometer
ParameterKey
IMS
Description
IMS instrument on(1)/off(0) status
Support
SupportQuantity
Other
Parameter #30
Name
Soft Particle Spectrometer
ParameterKey
SPS
Description
SPS instrument on(1)/off(0) status
Support
SupportQuantity
Other
Parameter #31
Name
Energetic Particle Detector
ParameterKey
EPD
Description
EPD instrument on(1)/off(0) status
Support
SupportQuantity
Other
Parameter #32
Name
Red Line Photometer
ParameterKey
RLP
Description
RLP instrument on(1)/off(0) status
Support
SupportQuantity
Other
Parameter #33
Name
Auroral Scanning Photometer
ParameterKey
ASP
Description
ASP instrument on(1)/off(0) status
Support
SupportQuantity
Other
Parameter #34
Name
start of swept-frequency portion
ParameterKey
swept_start
Description
scan line number of start of swept-frequency portion of the ionogram - separates the fixed- and swept-frequency portions
Support
SupportQuantity
Other
Parameter #35
Name
times of ionogram frequency markers
ParameterKey
Time_mark
Description
msec after frame sync - time of frequency markers
Units
ms
Structure
Size
22
ValidMin
3000.0
ValidMax
30000.0
Support
SupportQuantity
Temporal
Parameter #36
Name
values of ionogram frequency markers
ParameterKey
freq_mark
Description
ionogram frequency markers
Units
MHz
Structure
Size
22
ValidMin
0.1
ValidMax
20.0
Support
SupportQuantity
Other
Parameter #37
Name
number of delay times per ionogram scan-line
ParameterKey
vh_num
Description
each sounder-pulse transmission is followed by a scan of the sounder-receiver video amplitude output values for each delay time monitored after the transmitted pulse; these scans are called scan lines. There are two types of ISIS-2 binary ionogram files, one designated as "full" and one as "average" The full file has 892 delay times (one every 0.025ms). The average files are derived from the full files by averaging the amplitude values in 4 delay-time bins. Thus the average binary files contain 223 time-delay bins within each scan line. The cdf files were made from these average binary files.
Support
SupportQuantity
Other
Parameter #38
Name
number of ionogram scan-line frequencies
ParameterKey
f_num
Description
Ionogram files can be of different length. In some the swept-frequency portion covers the range 0.1 - 10 MHz, in others 0.1 - 20 MHz. Also, the proper start of each ionogram file, marked by a frame-sync pulse, was not always detected during the analog-to-digital (A/D) conversion. In such cases a frame sync was inserted to limit the file size. Thus the number of sounder-receiver video amplitude vs. delay time scan lines per ionogram can vary.
Support
SupportQuantity
Other
Parameter #39
Name
delay-time values
ParameterKey
delay_time
Description
delay-time values used in each scan line
Units
msec
Structure
Size
223
ValidMin
0.0
ValidMax
23.0
Support
SupportQuantity
Other
Parameter #40
Name
apparent-range values
ParameterKey
v_height
Description
apparent-range values used in each scan line
Units
km
Structure
Size
223
ValidMin
0.0
ValidMax
3333.33
Support
SupportQuantity
Other
Parameter #41
Name
Time
ParameterKey
Epoch
Description
Time
Units
ms
Support
SupportQuantity
Temporal
Parameter #42
Name
sounder receiver video amplitude
ParameterKey
ampl
Description
The color scale represents a linear sounder-receiver video amplitude output range from zero to 4.5 V expressed in terms of telemetry units from zero to 255. This calibration is based on the video calibration levels at the end of the listening period following each sounder pulse (these calibration levels produce the multi-colored stripe at the bottom of the digital ionograms). The sounder-receiver automatic-gain-control (AGC) voltage (from 0 to 5.12 volts) is obtained from a linear interpolation between the AGC trace displayed between 2400 km virtual range (16.0 ms) as 5.12 V and either 2805 km (18.7 ms) on the average ionograms or 2801.25 km (18.675 ms) on the full ionograms2805 km (18.7 ms) as 0 volts. On the average ionograms, which are available as either CDF or binary files from the NSSDC, the range resolution is 0.1 ms (corresponding to a virtual-range resolution of 15 km) there are 28 rows (27 intervals) covering the 0 to 5.12 V range; thus each row in virtual range above (decreasing delay time) the zero level (at 18.7 ms delay time) corresponds to an increase of 5.12/27 V of AGC with a quantization uncertainty of approximately plus or minus 0.1 V. Two rows have zero video-output amplitude values (on the average ionograms) in order that a clear AGC trace is visible on the ionograms. The row with the greatest virtual range corresponds to the actual AGC value. These AGC values were obtained from the pcm data corresponding to the ionogram of interest; these pcm files are available from the NSSDC. If the ionogram analysis program (also available from the NSSDC) is used, the AGC voltage corresponding to the scaling of each X- and O-mode trace point is given as part of the output file with the extension .tra. On the full ionograms, which are available as binary files from the NSSDC, the range resolution is 0.025 ms (corresponding to a virtual-range resolution of 3.75 km) and three rows have zero video-output amplitude values; the middle row corresponds to the actual AGC value.
Structure
Size
223
ValidMin
0
ValidMax
255
Wave
WaveType
PlasmaWaves
Qualifier
Magnitude
Qualifier
Pseudo
WaveQuantity
Intensity
FrequencyRange
SpectralRange
RadioFrequency
Low
0.1
High
20
Units
MHz
Parameter #43
Name
scan-line frequency
ParameterKey
freq
Description
frequency of each scan line; in the swept-frequency portion of the ionogram they correspond to interpolated values between the frequency markers
Units
MHz
ValidMin
0.1
ValidMax
20.0
Support
SupportQuantity
Other
Parameter #44
Name
Electron Gyrofrequency
ParameterKey
FH
Description
Electron Gyrofrequency at time of ionogram frame sync
Units
MHz
Support
SupportQuantity
Other