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1) Alouette-2 Topside Sounder Ionogram Data maxmize
Resource ID:spase://VWO/NumericalData/Alouette2/SFS/PT31S
Start:1965-11-29 13:42:37 Observatory:Alouette 2 Cadence:31 seconds
Stop:1968-01-01 04:11:45 Instrument:Alouette 2 Sweep-Frequency Sounder Resource:NumericalData
These ionograms were digitized from the original Alouette 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. The ionograms consist of swept-frequency operation (there is no fixed-frequency operation as in ISIS-1 and ISIS-2). The time resolution between ionograms is typically 31 seconds.

2) GIRO Ionogram-Derived Ionospheric Characteristics maxmize
Resource ID:spase://VWO/NumericalData/GIRO/CHARS.PT15M
Start:1987-01-01 00:00:05 Observatory:GIRO Group Cadence:15 minutes
Stop:2014-07-31 00:57:34 Instrument:GIRO Ionospheric Sounder Resource:NumericalData
Standard ionogram-derived characteristics obtained by Global Ionospheric Radio Observatory (GIRO) operated by University of Massachusetts Lowell. The list of standard URSI characteristics that can be derived from ionograms can be found in the SAO.XML Data Model Specification for standard ionosonde data exchange, Appendix C, http://ulcar.uml.edu/SAOXML/. In order to request the characteristics values from GIRO, it is necessary to call DIDBGetValues() servlet at GIRO server using standard HTTP call that returns a text document. The values in the document are calculated using automatic or manual interpretation of ionogram images. Each measurement is accompanied by a confidence score value (from 0 to 100, 100 is best autoscaled confidence or data obtained manually) and a set of two QD letters (qualitative and descriptive letters per URSI ionogram interpretation manual). When QD letters are set to //, reported value is obtained automatically, all other combinations of the letters correspond to manual scaling.

3) GIRO Ionogram Plots maxmize
Resource ID:spase://VWO/DisplayData/GIRO/GRM.PT15M
Start:1987-01-01 00:00:05 Observatory:GIRO Group Cadence:15 minutes
Stop:2014-07-31 00:57:33 Instrument:GIRO Ionospheric Sounder Resource:DisplayData
Collection of GIRO ionogram images at University of Massachusetts Lowell, covering selected ionosonde stations and periods of time from 1987-01-01 to current time, including 42 real-time data feeds. Total number of GIRO locations represented is 68 as of February 14, 2012. Access to images is arranged via a webpage containing a browsable data availability table. GIRO ionograms are visualized by plotting images in which received signal strength (color scale) is a function of echo delay (virtual range in vertical scale) and ionosonde frequency (horizontal scale) of the transmitted pulses. Echoes that can be used to derive remote vertical electron-density profiles, appear as discrete traces on ionograms. The ionogram traces are extracted (scaled) using image recognition software to obtain ionogram-derived characteristics of ionospheric plasma. Extracted traces and a table of major ionospheric characteristics are superimposed on the ionogram image

4) GIRO Doppler Skymap Plots maxmize
Resource ID:spase://VWO/DisplayData/GIRO/SKYMAP.PT15M
Start:1987-01-01 00:00:05 Observatory:GIRO Group Cadence:15 minutes
Stop:2014-07-31 00:57:33 Instrument:GIRO Ionospheric Sounder Resource:DisplayData
Collection of GIRO Doppler skymap images at University of Massachusetts Lowell, covering selected ionosonde stations and periods of time from 1993-07-20 to current time, including 28 real-time feeds. Total number of GIRO locations represented is 50 as of February 14, 2012. Access to images is arranged via a webpage containing a browsable data availability table. GIRO skymaps are visualized by plotting received echoes in the polar coordinate system using echo zenith and azimuth information. Color scale is used to represent Doppler Velocity of the signal reflection area in the ionosphere. Additionally, observed echoes on the skymap are used to derived zenith and azimuth of the ionospheric tilt, as well as vertical and horizontal components of the bulk ionospheric motion across the sounder location.

5) ISIS-1 Topside Sounder Ionograms maxmize
Resource ID:spase://VWO/NumericalData/ISIS1/SFS/Ionogram.PT29S
Start:1969-01-30 14:50:12 Observatory:ISIS 1 Cadence:24 seconds
Stop:1983-12-30 15:19:33 Instrument:ISIS1 Swept-Frequency Sounder Resource:NumericalData
These ionograms were digitized from the original ISIS-1 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. Each ionogram consists of a fixed-frequency and and a swept-frequency portion. The time resolution between ionograms is typically 29 seconds.

6) ISIS-2 Topside Sounder Ionograms maxmize
Resource ID:spase://VWO/NumericalData/ISIS2/SFS/Ionogram.PT22S
Start:1969-01-30 14:50:12 Observatory:ISIS 2 Cadence:22 seconds
Stop:1983-12-30 15:19:33 Instrument:ISIS2 Swept-Frequency Sounder Resource:NumericalData
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.

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