Ionosonde - Revision history

Strange Attractor: /* Digisonde operating modes */

2012-11-17T19:49:49Z

Digisonde operating modes

← Older revision		Revision as of 19:49, 17 November 2012
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-	== Digisonde operating modes ==	+	== Digisonde operating modes <sup>(5)</sup>==

	* '''Scanning ionogram:''' This is the basic mode, which results in the production of a standard ionogram. The system steps through frequencies according to the selected program, transmitting and coherently integrating a stream of N pulses. Prior to transmission on each frequency, four possible operating frequencies are monitored for interference and occupancy and the quietest is selected for the measurement. Then a few trial pulses are transmitted to allow automatic adjustment of receiver gain. As each coherent integration of pulse streams in completed, the raw output (i.e. 128 color coded amplitudes representing echoes at 128 heights) is added to the display of the developing ionogram. After all frequency steps have been completed the raw ionogram (16 complex Doppler lines at 256 heights and M frequency steps) is written out to a disk file. ARTIST, the automatic scaling program (Automatic Real-Time Ionogram Scaler with True height analysis), is invoked and a file of automatically scaled parameters is created and displayed.		* '''Scanning ionogram:''' This is the basic mode, which results in the production of a standard ionogram. The system steps through frequencies according to the selected program, transmitting and coherently integrating a stream of N pulses. Prior to transmission on each frequency, four possible operating frequencies are monitored for interference and occupancy and the quietest is selected for the measurement. Then a few trial pulses are transmitted to allow automatic adjustment of receiver gain. As each coherent integration of pulse streams in completed, the raw output (i.e. 128 color coded amplitudes representing echoes at 128 heights) is added to the display of the developing ionogram. After all frequency steps have been completed the raw ionogram (16 complex Doppler lines at 256 heights and M frequency steps) is written out to a disk file. ARTIST, the automatic scaling program (Automatic Real-Time Ionogram Scaler with True height analysis), is invoked and a file of automatically scaled parameters is created and displayed.

Strange Attractor: /* References */

2012-11-17T19:49:13Z

References

← Older revision		Revision as of 19:49, 17 November 2012
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	# G. Jacobs, W3ASK, T.J. Cohen, N4XX and R.B. Rose, K6GKU: "The new Shortwave Propagation Handbook", ''CQ Communications, Inc.'', ISBN 0-943016-11-8, 1995, pages 1-2 to 1-5.		# G. Jacobs, W3ASK, T.J. Cohen, N4XX and R.B. Rose, K6GKU: "The new Shortwave Propagation Handbook", ''CQ Communications, Inc.'', ISBN 0-943016-11-8, 1995, pages 1-2 to 1-5.
	# Zhigang Yuan, Baiqi Ning, Weixing Wan, Hong Yuan: "Acquirement and analysis of Doppler ionograms with high accuracy in the ionogram mode from Digisonde 256", ''Radio Science'', '''39''', RS2021, 2004.		# Zhigang Yuan, Baiqi Ning, Weixing Wan, Hong Yuan: "Acquirement and analysis of Doppler ionograms with high accuracy in the ionogram mode from Digisonde 256", ''Radio Science'', '''39''', RS2021, 2004.
		+	# NOAA: "[ftp://ftp.ngdc.noaa.gov/ionosonde/documentation/Digisonde/ Digisonde DPS4 Operations Manual]", 2007.

	==Further reading==		==Further reading==

Strange Attractor: /* Digisonde operating modes */

2012-11-17T19:37:45Z

Digisonde operating modes

← Older revision		Revision as of 19:37, 17 November 2012
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	* '''Fixed frequency ionogram:''' This is the same as a scanning ionogram except that the operating frequency remains the same, and no ionogram scaling is attempted.		* '''Fixed frequency ionogram:''' This is the same as a scanning ionogram except that the operating frequency remains the same, and no ionogram scaling is attempted.

-	* '''High resolution Doppler ionogram:''' Technically all Digisonde ionograms are Doppler ionograms since multiple Doppler lines (i.e. a Doppler spectrum) are created by the spectral domain integration for each range sampled. However, the pulse repetition rate is too rapid and the number of Doppler lines too few to adequately analyze Doppler spread. In order to get the optimum Doppler range and resolution for such an analysis the total integration period should be tens of seconds, therefore modes were developed which multiplex the coherent integration of echoes at several frequency steps simultaneously by switching frequencies between pulses.	+	* '''High resolution Doppler ionogram:''' Technically all Digisonde ionograms are Doppler ionograms since multiple Doppler lines (i.e. a Doppler spectrum) are created by the spectral domain integration for each range sampled. However, the pulse repetition rate is too rapid and the number of Doppler lines too few to adequately analyze Doppler spread. In order to get the optimum Doppler range and resolution for such an analysis the total integration period should be tens of seconds, therefore modes were developed which multiplex the coherent integration of echoes at several frequency steps simultaneously by switching frequencies between pulses.<sup>(4)</sup>

	* '''Drift ionogram:''' This is similar to the Doppler Ionogram in that higher Doppler resolution is achieved by extending the integration period. In addition to multiplexing frequencies the receive antennas are also multiplexed. This provides a raw data file which records the relative phase of all Doppler lines of all echoes on the four antennas in the receiver array, giving the angle of arrival of the individual echoes.		* '''Drift ionogram:''' This is similar to the Doppler Ionogram in that higher Doppler resolution is achieved by extending the integration period. In addition to multiplexing frequencies the receive antennas are also multiplexed. This provides a raw data file which records the relative phase of all Doppler lines of all echoes on the four antennas in the receiver array, giving the angle of arrival of the individual echoes.

Strange Attractor: /* References */

2012-11-17T19:36:57Z

References

← Older revision		Revision as of 19:36, 17 November 2012
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	# F.C. Judd, G2BCX: "Radio Wave Propagation (HF Bands)", ''Heinemann'', London, ISBN 0-434-90926-2, 1987, pages 12–20,27–37		# F.C. Judd, G2BCX: "Radio Wave Propagation (HF Bands)", ''Heinemann'', London, ISBN 0-434-90926-2, 1987, pages 12–20,27–37
	# G. Jacobs, W3ASK, T.J. Cohen, N4XX and R.B. Rose, K6GKU: "The new Shortwave Propagation Handbook", ''CQ Communications, Inc.'', ISBN 0-943016-11-8, 1995, pages 1-2 to 1-5.		# G. Jacobs, W3ASK, T.J. Cohen, N4XX and R.B. Rose, K6GKU: "The new Shortwave Propagation Handbook", ''CQ Communications, Inc.'', ISBN 0-943016-11-8, 1995, pages 1-2 to 1-5.
		+	# Zhigang Yuan, Baiqi Ning, Weixing Wan, Hong Yuan: "Acquirement and analysis of Doppler ionograms with high accuracy in the ionogram mode from Digisonde 256", ''Radio Science'', '''39''', RS2021, 2004.

	==Further reading==		==Further reading==

Strange Attractor: /* The HAARP digisonde */

2012-11-17T19:23:26Z

The HAARP digisonde

← Older revision		Revision as of 19:23, 17 November 2012
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	The ionogram also shows what appear to be faint reflections from an altitude of 425 km. In reality, these chart points are the result of the sounder's radar signal being reflected by the ionosphere, returning to the ground where they are reflected back to the ionosphere for a second reflection before being detected by the Digisonde receiver. The time-of-flight is, therefore twice that of the normal reflection and the computed virtual height is twice the normal virtual height. This type of presentation is often seen under conditions of low ionospheric absorption.		The ionogram also shows what appear to be faint reflections from an altitude of 425 km. In reality, these chart points are the result of the sounder's radar signal being reflected by the ionosphere, returning to the ground where they are reflected back to the ionosphere for a second reflection before being detected by the Digisonde receiver. The time-of-flight is, therefore twice that of the normal reflection and the computed virtual height is twice the normal virtual height. This type of presentation is often seen under conditions of low ionospheric absorption.
		+
		+
		+	== Digisonde operating modes ==
		+
		+	* '''Scanning ionogram:''' This is the basic mode, which results in the production of a standard ionogram. The system steps through frequencies according to the selected program, transmitting and coherently integrating a stream of N pulses. Prior to transmission on each frequency, four possible operating frequencies are monitored for interference and occupancy and the quietest is selected for the measurement. Then a few trial pulses are transmitted to allow automatic adjustment of receiver gain. As each coherent integration of pulse streams in completed, the raw output (i.e. 128 color coded amplitudes representing echoes at 128 heights) is added to the display of the developing ionogram. After all frequency steps have been completed the raw ionogram (16 complex Doppler lines at 256 heights and M frequency steps) is written out to a disk file. ARTIST, the automatic scaling program (Automatic Real-Time Ionogram Scaler with True height analysis), is invoked and a file of automatically scaled parameters is created and displayed.
		+
		+	* '''Fixed frequency ionogram:''' This is the same as a scanning ionogram except that the operating frequency remains the same, and no ionogram scaling is attempted.
		+
		+	* '''High resolution Doppler ionogram:''' Technically all Digisonde ionograms are Doppler ionograms since multiple Doppler lines (i.e. a Doppler spectrum) are created by the spectral domain integration for each range sampled. However, the pulse repetition rate is too rapid and the number of Doppler lines too few to adequately analyze Doppler spread. In order to get the optimum Doppler range and resolution for such an analysis the total integration period should be tens of seconds, therefore modes were developed which multiplex the coherent integration of echoes at several frequency steps simultaneously by switching frequencies between pulses.
		+
		+	* '''Drift ionogram:''' This is similar to the Doppler Ionogram in that higher Doppler resolution is achieved by extending the integration period. In addition to multiplexing frequencies the receive antennas are also multiplexed. This provides a raw data file which records the relative phase of all Doppler lines of all echoes on the four antennas in the receiver array, giving the angle of arrival of the individual echoes.
		+
		+	* '''Oblique ionogram:''' This is the same as a Scanning Ionogram and results in a raw data display and disk file.

	== See also ==		== See also ==

Strange Attractor: /* The HAARP digisonde */

2012-05-01T13:51:57Z

The HAARP digisonde

← Older revision		Revision as of 13:51, 1 May 2012
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	''This paragraph consists of [http://www.haarp.alaska.edu/haarp/privacy.html Public domain] material from the [http://www.haarp.alaska.edu/haarp/dsonde.html HAARP website]''		''This paragraph consists of [http://www.haarp.alaska.edu/haarp/privacy.html Public domain] material from the [http://www.haarp.alaska.edu/haarp/dsonde.html HAARP website]''

-	The [[HAARP]] Digisonde, which was developed and provided by the University of Massachusetts at Lowell, was one of the first instruments installed at the HAARP Research Station. The purposes of this instrument are to support frequency management of the 3600 ~~kilowatt~~ Ionospheric Research Instrument transmitter and to provide real time ionospheric characteristics for guiding experiment selection. The Digisonde data are processed, archived, and are available for post-analysis of experiment results. Various formats of the information derived from the Digisonde are made available on the HAARP web site in chart form in near real time and can be accessed from the Data Index.	+	The [[HAARP]] Digisonde, which was developed and provided by the University of Massachusetts at Lowell, was one of the first instruments installed at the HAARP Research Station. The purposes of this instrument are to support frequency management of the 3600 kW Ionospheric Research Instrument transmitter and to provide real time ionospheric characteristics for guiding experiment selection. The Digisonde data are processed, archived, and are available for post-analysis of experiment results. Various formats of the information derived from the Digisonde are made available on the HAARP web site in chart form in near real time and can be accessed from the Data Index.
	[[Image:HAARP-Ionogram.gif\|left\|250px]]		[[Image:HAARP-Ionogram.gif\|left\|250px]]
	An example, annotated ionogram is shown in the figure to the left. Annotations in this figure are in blue lettering. (Click on the figure to see a full size image.)		An example, annotated ionogram is shown in the figure to the left. Annotations in this figure are in blue lettering. (Click on the figure to see a full size image.)

Strange Attractor: alternative meaning

2011-07-07T21:00:01Z

alternative meaning

← Older revision		Revision as of 21:00, 7 July 2011
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	[[Image:IRX-58-23-ionosonde.jpg\|250px\|thumb\|right\|An IRX-58-23 ionosonde system.]]		[[Image:IRX-58-23-ionosonde.jpg\|250px\|thumb\|right\|An IRX-58-23 ionosonde system.]]
-	An '''ionosonde''' or '''ionospheric sounder''' (colloq. '''chirpsounder'''), is a specialized radar system for the examination of the [[ionosphere]]. An ionosonde is used for finding the optimum operation frequencies for broadcasts or two-way communications in the high frequency range.	+	An '''ionosonde''' or '''ionospheric sounder''' (colloq. '''chirpsounder'''), is a specialized radar system for the examination of the [[ionosphere]]. An ionosonde is used for finding the optimum operation frequencies for broadcasts or two-way communications in the high frequency range.<sup>(1)</sup>

	==Description==		==Description==

-	Ionospheric reflection of radio waves was discovered in 1924 by Edward Victor Appleton. The basic ionosonde technology was invented in 1925 by Gregory Breit and Merle A. Tuve <sup>(1) (2)</sup> and further developed in the late 1920s by a number of prominent physicists, including E. V. Appleton. The term ''[[ionosphere]]'' and, hence, the etymology of its derivatives, was proposed by Robert Watson-Watt.	+	Ionospheric reflection of radio waves was discovered in 1924 by Edward Victor Appleton. The basic ionosonde technology was invented in 1925 by Gregory Breit and Merle A. Tuve <sup>(2)</sup> <sup>(3)</sup> and further developed in the late 1920s by a number of prominent physicists, including E. V. Appleton. The term ''[[ionosphere]]'' and, hence, the etymology of its derivatives, was proposed by Robert Watson-Watt.

	An ionosonde consists of:		An ionosonde consists of:
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	==References==		==References==
		+	# The term ''ionosonde'' was also used in the past to describe a balloon-borne upper atmospheric research device, used in determining the amount of ionizing radiation in the atmosphere caused primarily by nuclear testing. See H. Odishaw: "Glossary", ''Bulletin of the Atomic Scientists'', May 1961, pp. 257. Also [http://tech.groups.yahoo.com/group/ionosonde/ Ionosonde Yahoo group].
	# F.C. Judd, G2BCX: "Radio Wave Propagation (HF Bands)", ''Heinemann'', London, ISBN 0-434-90926-2, 1987, pages 12–20,27–37		# F.C. Judd, G2BCX: "Radio Wave Propagation (HF Bands)", ''Heinemann'', London, ISBN 0-434-90926-2, 1987, pages 12–20,27–37
	# G. Jacobs, W3ASK, T.J. Cohen, N4XX and R.B. Rose, K6GKU: "The new Shortwave Propagation Handbook", ''CQ Communications, Inc.'', ISBN 0-943016-11-8, 1995, pages 1-2 to 1-5.		# G. Jacobs, W3ASK, T.J. Cohen, N4XX and R.B. Rose, K6GKU: "The new Shortwave Propagation Handbook", ''CQ Communications, Inc.'', ISBN 0-943016-11-8, 1995, pages 1-2 to 1-5.

Strange Attractor: full name

2011-07-07T20:47:15Z

full name

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	[[Image:IRX-58-23-ionosonde.jpg\|250px\|thumb\|right\|An IRX-58-23 ionosonde system.]]		[[Image:IRX-58-23-ionosonde.jpg\|250px\|thumb\|right\|An IRX-58-23 ionosonde system.]]
-	An '''ionosonde''' (or '''chirpsounder''') is a specialized radar system for the examination of the [[ionosphere]]. An ionosonde is used for finding the optimum operation frequencies for broadcasts or two-way communications in the high frequency range.	+	An '''ionosonde''' or '''ionospheric sounder''' (colloq. '''chirpsounder'''), is a specialized radar system for the examination of the [[ionosphere]]. An ionosonde is used for finding the optimum operation frequencies for broadcasts or two-way communications in the high frequency range.

	==Description==		==Description==

Strange Attractor: /* Operation */

2011-05-06T13:42:17Z

Operation

← Older revision		Revision as of 13:42, 6 May 2011
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	The frequency Fc at which a wave just penetrates a layer of ionisation is known as the critical frequency of that layer. The critical frequency is related to the electron density in the specific layer (D, E, F1 or F2).		The frequency Fc at which a wave just penetrates a layer of ionisation is known as the critical frequency of that layer. The critical frequency is related to the electron density in the specific layer (D, E, F1 or F2).

-	All transmitted frequencies above this critical frequency will penetrate the layer without being reflected. Their group velocity, however, will be slowed by any ionisation, and this will add to the time-of-flight. If such a wave encounters another layer whose plasma frequency is higher than the frequency of the wave, it will be reflected, and the return signal will be further delayed as it travels back through the underlying ionisation. Therefore, HF frequencies between 5 and 30 MHz pass through the E layer and are reflected at the F layer. Similarly, MF frequencies (AM broadcast stations) at night pass through the D layer and are reflected by the E layer. When a ''sporadic E'' cloud passes over the ionosonde, then foEs becomes very high, often ~~over~~ exceeding 25 MHz. This high reflection frequency allows medium distance ionospheric communications and TV DX reception in the low VHF range (28, 50 and even 70 MHz) with very strong signal stengths.	+	All transmitted frequencies above this critical frequency will penetrate the layer without being reflected. Their group velocity, however, will be slowed by any ionisation, and this will add to the time-of-flight. If such a wave encounters another layer whose plasma frequency is higher than the frequency of the wave, it will be reflected, and the return signal will be further delayed as it travels back through the underlying ionisation. Therefore, HF frequencies between 5 and 30 MHz pass through the E layer and are reflected at the F layer. Similarly, MF frequencies (AM broadcast stations) at night pass through the D layer and are reflected by the E layer. When a ''sporadic E'' cloud passes over the ionosonde, then foEs becomes very high, often exceeding 25 MHz. This high reflection frequency allows medium distance ionospheric communications and TV DX reception in the low VHF range (28, 50 and even 70 MHz) with very strong signal stengths.

	==Ionogram==		==Ionogram==

Strange Attractor: /* The HAARP digisonde */

2011-01-14T18:30:37Z

The HAARP digisonde

← Older revision		Revision as of 18:30, 14 January 2011
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	==The HAARP digisonde==		==The HAARP digisonde==

-	''[http://www.haarp.alaska.edu/haarp/privacy.html Public domain] material from the [http://www.haarp.alaska.edu/haarp/dsonde.html HAARP website]''	+	''This paragraph consists of [http://www.haarp.alaska.edu/haarp/privacy.html Public domain] material from the [http://www.haarp.alaska.edu/haarp/dsonde.html HAARP website]''

	The [[HAARP]] Digisonde, which was developed and provided by the University of Massachusetts at Lowell, was one of the first instruments installed at the HAARP Research Station. The purposes of this instrument are to support frequency management of the 3600 kilowatt Ionospheric Research Instrument transmitter and to provide real time ionospheric characteristics for guiding experiment selection. The Digisonde data are processed, archived, and are available for post-analysis of experiment results. Various formats of the information derived from the Digisonde are made available on the HAARP web site in chart form in near real time and can be accessed from the Data Index.		The [[HAARP]] Digisonde, which was developed and provided by the University of Massachusetts at Lowell, was one of the first instruments installed at the HAARP Research Station. The purposes of this instrument are to support frequency management of the 3600 kilowatt Ionospheric Research Instrument transmitter and to provide real time ionospheric characteristics for guiding experiment selection. The Digisonde data are processed, archived, and are available for post-analysis of experiment results. Various formats of the information derived from the Digisonde are made available on the HAARP web site in chart form in near real time and can be accessed from the Data Index.
-		+	[[Image:HAARP-Ionogram.gif\|left\|250px]]
	An example, annotated ionogram is shown in the figure to the left. Annotations in this figure are in blue lettering. (Click on the figure to see a full size image.)		An example, annotated ionogram is shown in the figure to the left. Annotations in this figure are in blue lettering. (Click on the figure to see a full size image.)