Data Description

This page summarizes information about the selected resource and its origin based on SPASE metadata.

Table of Contents

  1. Product
  2. Repository
  3. Instrument
  4. ObservatoryObservatories
  5. Persons

SPASE version 2.2.1

Numerical Data Product: ISIS-2 Topside Sounder Ionograms

Resource ID
spase://VWO/NumericalData/ISIS2/SFS/Ionogram.PT22S Get XML
Name
ISIS-2 Topside Sounder Ionograms
Alternate name
ISIS-2 Topside Sounder Ionogram CDFs at NASA's CDAWeb
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.

Additional information
ISIS/Alouette Topside Sounder Data Restoration Project

ISIS/Alouette page maintained by NASA GSFC with science and instrument descriptions, data access, software, and publication lists

Language
en
NSSDC's Master Catalog

Information about the Sweep Frequency Sounder experiment on ISIS-2.

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.

Contact
Role Person
1. Principal investigator Dr. J. H. Whitteker Get XML
2. General contact Dr. Robert F. Benson Get XML
3. General contact Dieter K. Bilitza Get XML
Release date
2012-02-24 17:51:27
Prior ID
spase://VWO/NumericalData/ISIS2/SFS/ISIS2_Ionogram_CDF_PT22S
Repository
Name
CDAWeb Data Repository FTP Interface Get XML
Availability
Online
Access rights
Open
URL
CDAWeb FTP access to ISIS-2 Ionogram CDFs

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 http://nssdc.gsfc.nasa.gov/space/isis/isis-table1-new.html A merged data set, independent of the ground stations, is planned.

Language
en
CDAWeb web access portal to ISIS-2 Ionogram data

Repository of ISIS-2 data in CDF format at NASA CDAWeb, accessible via web interface.

Language
en
Format
CDF
Encoding
None
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.

Processing level
Calibrated
Instrument
ISIS2 Swept-Frequency Sounder Get XML
Measurement type
Spectrum
Active waves
Temporal description
Start date
1969-01-30 14:50:12
Stop date
1983-12-30 15:19:33
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
22 seconds
Spectral range
RadioFrequency
Observed regions
Earth.Magnetosphere
Earth.Magnetosphere.Polar
Earth.NearSurface.AuroralRegion
Earth.NearSurface.Ionosphere
Earth.NearSurface.Ionosphere.Topside
Earth.NearSurface.PolarCap
Caveats

See discussion on "How To Detect Erroneous ISIS-2 Digital Ionogram Files" at http://nssdc.gsfc.nasa.gov/space/isis/isis_read_error.html

Keywords
AKR
FAI
Ionogram
ducted echoes
field-aligned irregularities
fixed- and swept-frequency sounder
ground echoes
ground reflections
ionospheric echoes
ionospheric reflections
plasma resonance
plasma waves
solar type III bursts
topside ionosphere
topside sounder
upper-hybrid noise band
wave scattering
↑

Parameters

Parameter #1

Name
satellite ID
Parameter key
satellite
Description

sat.-ID: 1=AL1, 2=AL2, 3=ISIS1, 4=ISIS2

Parameter type
Other

Parameter #2

Name
telemetry station code
Parameter key
station_id
Description

two-digit telemetry station code

Parameter type
Other

Parameter #3

Name
transmitter power code
Parameter key
power_code
Description

trans. power code: 1=Prim(400W) 2=Sec(400W)

Parameter type
Other

Parameter #4

Name
sounder/receiver code
Parameter key
s/r_code
Description

sounder/receiver code: 0=off, 1=on

Parameter type
Other

Parameter #5

Name
swept frequency range code
Parameter key
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)

Parameter type
Other

Parameter #6

Name
DMODE code
Parameter key
DMODE
Description

DMODE (transm. on/off for alternate frame pairs): 0=off, 1=on

Parameter type
Other

Parameter #7

Name
GMODE code
Parameter key
GMODE
Description

GMODE (transmission of alternate frames of fixed-frequency ionograms and normal combined fixed- and swept-frequency ionograms): 0=off, 1=on"

Parameter type
Other

Parameter #8

Name
sounder mixed mode
Parameter key
mixed_mode
Description

sounder mixed mode (transmission at a fixed-frequency while the sounder receiver sweeps over swept-frequency range): 0=off, 1=on

Parameter type
Other

Parameter #9

Name
AIT mode
Parameter key
AIT_mode
Description

AIT mode (automatic sounder operation every 3 min): 0=off, 1=on

Parameter type
Other

Parameter #10

Name
fixed frequency code (0-6)
Parameter key
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

Parameter type
Other

Parameter #11

Name
Year
Parameter key
year
Description

Year of ionogram frame sync in UT

Parameter type
Other

Parameter #12

Name
Day of Year
Parameter key
doy
Description

Day of Year of ionogram frame sync in UT

Parameter type
Other

Parameter #13

Name
Hour
Parameter key
hr
Description

Hour of ionogram frame sync in UT

Parameter type
Other

Parameter #14

Name
Minute
Parameter key
min
Description

Minute of hour of ionogram frame sync in UT

Parameter type
Other

Parameter #15

Name
Second
Parameter key
sec
Description

Second of minute of ionogram frame sync in UT

Parameter type
Other

Parameter #16

Name
Local Mean Time (hh,mm)
Parameter key
LMT
Description

Local Mean Time (hh,mm) at time of ionogram frame sync

Structure
Size
2
Elements
Index Name Units
1 LMT(hh) hrs
2 LMT(mm) min
Parameter type
Other

Parameter #17

Name
geog coord (Lat,Long,Hgt)
Parameter key
geo_coord
Description

geographic coordinates (Lat,Long,Hgt) at time of ionogram frame sync

Structure
Size
2
Elements
Index Name Units
1 latitude deg
2 longitude deg
3 height km
Parameter type
Positional

Parameter #18

Name
Geomagnetic Local Time (hh,mm)
Parameter key
GMLMT
Description

Geomagnetic Local Time (HHMM) at time of ionogram frame sync

Structure
Size
2
Elements
Index Name
1 GMLMT(hh)
2 GMLMT(mm)
Parameter type
Other

Parameter #19

Name
geom latitude
Parameter key
GMLAT
Description

geomagnetic latitude at time of ionogram frame sync

Units
deg
Parameter type
Positional

Parameter #20

Name
geom longitude
Parameter key
GMLONG
Description

geomagnetic longitude at time of ionogram frame sync

Units
deg
Parameter type
Positional

Parameter #21

Name
inv latitude
Parameter key
INV_LAT
Description

invariant latitude at time of ionogram frame sync

Units
deg
Parameter type
Other

Parameter #22

Name
magnetic inclination
Parameter key
DIP
Description

Dip angle of mag field direction at time of ionogram frame sync

Units
deg
Parameter type
Other

Parameter #23

Name
Solar Zenith Angle
Parameter key
CHI
Description

Solar Zenith Angle at time of ionogram frame sync

Units
deg
Parameter type
Other

Parameter #24

Name
L shell (McIlwain parameter)
Parameter key
L
Description

L shell (McIlwain parameter) at time of ionogram frame sync

Parameter type
Positional

Parameter #25

Name
spacecraft in/out sunlight
Parameter key
sun
Description

spacecraft in(=1)/out(=2) sunlight at time of ionogram frame sync

Parameter type
Other

Parameter #26

Name
Cyl. Electrost. Probe
Parameter key
CEP
Description

CEP instrument on(1)/off(0) status

Parameter type
Other

Parameter #27

Name
0.05-30 kHz VLF receiver
Parameter key
VLF
Description

VLF receiver on(1)/off(0) status

Parameter type
Other

Parameter #28

Name
Retarding Potential Analyzer
Parameter key
RPA
Description

RPA instrument on(1)/off(0) status

Parameter type
Other

Parameter #29

Name
Ion Mass Spectrometer
Parameter key
IMS
Description

IMS instrument on(1)/off(0) status

Parameter type
Other

Parameter #30

Name
Soft Particle Spectrometer
Parameter key
SPS
Description

SPS instrument on(1)/off(0) status

Parameter type
Other

Parameter #31

Name
Energetic Particle Detector
Parameter key
EPD
Description

EPD instrument on(1)/off(0) status

Parameter type
Other

Parameter #32

Name
Red Line Photometer
Parameter key
RLP
Description

RLP instrument on(1)/off(0) status

Parameter type
Other

Parameter #33

Name
Auroral Scanning Photometer
Parameter key
ASP
Description

ASP instrument on(1)/off(0) status

Parameter type
Other

Parameter #34

Name
start of swept-frequency portion
Parameter key
swept_start
Description

scan line number of start of swept-frequency portion of the ionogram - separates the fixed- and swept-frequency portions

Parameter type
Other

Parameter #35

Name
times of ionogram frequency markers
Parameter key
Time_mark
Description

msec after frame sync - time of frequency markers

Units
ms
Structure
Size
22
Valid minimum
3000.0
Valid maximum
30000.0
Parameter type
Temporal

Parameter #36

Name
values of ionogram frequency markers
Parameter key
freq_mark
Description

ionogram frequency markers

Units
MHz
Structure
Size
22
Valid minimum
0.1
Valid maximum
20.0
Parameter type
Other

Parameter #37

Name
number of delay times per ionogram scan-line
Parameter key
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.

Parameter type
Other

Parameter #38

Name
number of ionogram scan-line frequencies
Parameter key
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.

Parameter type
Other

Parameter #39

Name
delay-time values
Parameter key
delay_time
Description

delay-time values used in each scan line

Units
msec
Structure
Size
223
Valid minimum
0.0
Valid maximum
23.0
Parameter type
Other

Parameter #40

Name
apparent-range values
Parameter key
v_height
Description

apparent-range values used in each scan line

Units
km
Structure
Size
223
Valid minimum
0.0
Valid maximum
3333.33
Parameter type
Other

Parameter #41

Name
Time
Parameter key
Epoch
Description

Time

Units
ms
Parameter type
Temporal

Parameter #42

Name
sounder receiver video amplitude
Parameter key
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
Valid minimum
0
Valid maximum
255
Wave type
Plasma waves
Quantity
Intensity
Qualifier
Magnitude
Pseudo
Frequency range
Spectral range
RadioFrequency
Low frequency
0.1
High frequency
20
Units
MHz

Parameter #43

Name
scan-line frequency
Parameter key
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
Valid minimum
0.1
Valid maximum
20.0
Parameter type
Other

Parameter #44

Name
Electron Gyrofrequency
Parameter key
FH
Description

Electron Gyrofrequency at time of ionogram frame sync

Units
MHz
Parameter type
Other
↑

SPASE version 2.1.0

Instrument: ISIS2 Swept-Frequency Sounder

Instrument ID
spase://SMWG/Instrument/ISIS2/SFS Get XML
Name
ISIS2 Swept-Frequency Sounder
Alternate name
Topside Sounder
Description

The ISIS 2 (International Satellites for Ionospheric Studies) Swept-Frequency Sounder measured the ionospheric electron density in the altitude range 300 to 1400 km, and provided correlative data for the other ISIS 2 experiments, particularly those measuring ionospheric parameters. The ionosonde was a radio transmitter that recorded the time delay between a transmitted and returned radio-frequency pulse. A continuum of frequencies between 0.1 and 20 MHz was sampled every 14 or 21 s, and one of six selected frequencies was also used for sounding for a few seconds during each 14- or 21-s period. In addition to the sweep- and fixed-frequency modes of operation, a mixed mode was available in which the transmitter frequency was fixed at one of six possible frequencies while the receiver swept. Several virtual-range (delay-time) traces resulting from ground reflections, plasma resonances, birefringence of the ionosphere, nonvertical propagation, etc., were normally observed.

Additional information
NSSDC's Master Catalog

Information about the Swept-Frequency Sounder on ISIS 2

Contact
Role Person
1. Principal investigator Dr. J. H. Whitteker Get XML
Release date
2010-08-05 14:57:27
Instrument type
Sounder
Investigation name
Swept-Frequency Sounder on ISIS 2
Observatory
ISIS 2 Get XML
↑

SPASE version 2.2.0

Observatory: ISIS 2

Observatory ID
spase://SMWG/Observatory/ISIS2 Get XML
Name
ISIS 2
Alternate name
1971-024A
International Sats for Ionosph Studies
ISIS-B
Description

ISIS 2 was an ionospheric observatory instrumented with a sweep- and a fixed-frequency ionosonde, a VLF receiver, energetic and soft particle detectors, an ion mass spectrometer, an electrostatic probe, a retarding potential analyzer, a beacon transmitter, a cosmic noise experiment, and two photometers. Two long crossed-dipole antennas (73 and 18.7 m) were used for the sounding, VLF, and cosmic noise experiments. The spacecraft was spin-stabilized to about 2 rpm after antenna deployment. There were two basic orientation modes for the spacecraft, cartwheel and orbit-aligned. The spacecraft operated approximately the same length of time in each mode, remaining in one mode typically 3 to 5 months. The cartwheel mode with the axis perpendicular to the orbit plane was made available to provide ram and wake data for some experiments for each spin period, rather than for each orbit period. Attitude and spin information was obtained from a three-axis magnetometer and a sun sensor. Control of attitude and spin was possible by means of magnetic torquing. The experiment package also included a programmable tape recorder with a 1-h capacity. For nonrecorded observations, data from satellite and subsatellite regions were telemetered when the spacecraft was in the line of sight of a telemetry station. Telemetry stations were located so that primary data coverage was near the 80-deg-W meridian and near Hawaii, Singapore, Australia, England, France, Norway, India, Japan, Antarctica, New Zealand, and Central Africa. NASA support of the ISIS project was terminated on October 1, 1979. A significant amount of experimental data, however, was acquired after this date by the Canadian project team. ISIS 2 operations were terminated in Canada on March 9, 1984. The Radio Research Laboratories (Tokyo, Japan) then requested and received permission to reactivate ISIS 2. Regular ISIS 2 operations were started from Kashima, Japan, in early August 1984. ISIS 2 was deactivated effective 24, 1990. A data restoration effort began in the late ninties and successfully saved a considerable portion of the high-resolution data before the telemetry tapes were discarted. More information about this effort and access to the data on CDAWeb and nssdcftp can be found at

http://nssdc.gsfc.nasa.gov/space/isis/isis-status.html

Additional information
NSSDC's Master Catalog

Information about the ISIS 2 mission

Contact
Role Person
1. Project scientist Mr. John E. Jackson Get XML
2. Team leader Mr. Larry H. Brace Get XML
3. Project scientist Dr. Theodore R. Hartz Get XML
Release date
2010-10-01 19:58:07
Observatory group
ISIS Satellites Get XML
Location
Region
Earth.NearSurface.Ionosphere
↑

SPASE version 2.2.0

Observatory: ISIS Satellites

Observatory ID
spase://SMWG/Observatory/ISIS Get XML
Name
ISIS Satellites
Alternate name
International Sats for Ionosph Studies
Description

ISIS ionospheric observatories

Contact
Role Person
1. Project scientist Dr. Irvine Paghis Get XML
2. Project scientist Mr. John E. Jackson Get XML
3. Team leader Mr. Larry H. Brace Get XML
Release date
2010-10-01 19:58:02
Location
Region
Earth.NearSurface.Ionosphere
↑

SPASE version 2.2.0

Person: Dr. J. H. Whitteker

Name
Dr. J. H. Whitteker
Organization
Communications Research Centre
Person ID
spase://SMWG/Person/J.H.Whitteker Get XML
↑

SPASE version 2.2.0

Person: Dr. Robert F. Benson

Name
Dr. Robert F. Benson
Organization
GSFC-Code 612.2
Person ID
spase://SMWG/Person/Robert.F.Benson Get XML
↑

SPASE version 2.2.0

Person: Dieter K. Bilitza

Name
Dieter K. Bilitza
Organization
NASA/GSFC, Code 672
Phone
+1 301 286 0190
Person ID
spase://SMWG/Person/Dieter.K.Bilitza Get XML
Release date
2010-08-05 17:35:46
↑

SPASE version 2.2.0

Person: Dr. Robert E. McGuire

Name
Dr. Robert E. McGuire
Organization
NASA Goddard Space Flight Center
Address
Code 672, Greenbelt, MD 20771, USA
Email
mcguire@mail630.gsfc.nasa.gov
Phone
+1 301 286 7794
Person ID
spase://SMWG/Person/Robert.E.McGuire Get XML
Release date
2010-08-05 17:35:47
↑

SPASE version 2.2.0

Person: Mr. John E. Jackson

Name
Mr. John E. Jackson
Organization
Deceased - formerly at GSFC and NSSDC
Person ID
spase://SMWG/Person/John.E.Jackson Get XML
Release date
2010-08-05 17:35:46
↑

SPASE version 2.2.0

Person: Mr. Larry H. Brace

Name
Mr. Larry H. Brace
Organization
GSFC-Code 910.4
Phone
+1-301-286-8575
Person ID
spase://SMWG/Person/Larry.H.Brace Get XML
Release date
2010-08-05 17:35:47
↑

SPASE version 2.2.0

Person: Dr. Theodore R. Hartz

Name
Dr. Theodore R. Hartz
Organization
Retired - former Upper Atmosphere Consultant, Canada
Person ID
spase://SMWG/Person/Theodore.R.Hartz Get XML
Release date
2010-08-05 17:35:47
↑

SPASE version 2.2.0

Person: Dr. Irvine Paghis

Name
Dr. Irvine Paghis
Organization
Deceased - formerly at CRC, Canada
Person ID
spase://SMWG/Person/Irvine.Paghis Get XML
Release date
2010-08-05 17:35:46
↑

SPASE version 2.2.0

Repository: CDAWeb Data Repository FTP Interface

Repository ID
spase://SMWG/Repository/NASA/GSFC/SPDF/CDAWeb Get XML
Name
CDAWeb Data Repository FTP Interface
Description

Coordinated Data Analysis Web (CDAWeb) supports not only interactive plotting of variables from multiple instruments on multiple investigations simultaneously on arbitrary, user-defined time-scales. It also supports data retrieval in various formats using its interactive web interface or ftp service.

Additional information
CDAWeb Home Page

Coordinated Data Analysis Web (CDAWeb) home page at Space Physics Data Facility of the NASA Goddard Space Flight Center.

Contact
Role Person
1. Project scientist Dr. Robert E. McGuire Get XML
Release date
2011-02-23 18:39:43
Prior ID
spase://VMO/Repository/CDAWeb
Access URL
FTP Access to CDAWeb Data
↑