Trans-Equatorial Propagation - Revision history

G4WLC: /* Why does TEP occur over the Equator? */

2012-03-25T01:39:56Z

Why does TEP occur over the Equator?

← Older revision		Revision as of 18:39, 24 March 2012
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	==Why does TEP occur over the Equator?==		==Why does TEP occur over the Equator?==

	There are three general "zones" in the atmosphere of the Earth, Polar, Temperate and Equatorial. In terms of density, it has been found that equatorial ionosphereic areas are more dense than those over polar regions. This affects useable ~~requencies~~ within those regions. ~~perhaps~~ because they are at the "~~exteremes~~" of the earth in terms of their exposure to the effects of the sun, the polar and equatorial regions are subject to various unusual and unexpected variations in ionospheric conditions - ~~thes eoften~~ occuring in the F-Layer.		There are three general "zones" in the atmosphere of the Earth, Polar, Temperate and Equatorial. In terms of density, it has been found that equatorial ionosphereic areas are more dense than those over polar regions. This affects useable frequencies within those regions. Perhaps because they are at the "extremes" of the earth in terms of their exposure to the effects of the sun, the polar and equatorial regions are subject to various unusual and unexpected variations in ionospheric conditions - these often occuring in the F-Layer.

	Perhaps the most interesting of these effects is known as the "equatorial anomoly". This occurs where a high electron concentration is found on each side of the magnetic equator, and is usually seen in the region of 10 to 20 degrees latitude.		Perhaps the most interesting of these effects is known as the "equatorial anomoly". This occurs where a high electron concentration is found on each side of the magnetic equator, and is usually seen in the region of 10 to 20 degrees latitude.

Carlb: /* Is it possible to predict TEP conditions? */

2009-04-09T01:36:31Z

Is it possible to predict TEP conditions?

← Older revision		Revision as of 18:36, 8 April 2009
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	* The higher the F2 layer is over the geomagnetic equator the higher the occurrence rate of TEP.		* The higher the F2 layer is over the geomagnetic equator the higher the occurrence rate of TEP.
	* The further the equatorial anomalies are from the geomagnetic equator the higher the probability that afternoon TEP will occur		* The further the equatorial anomalies are from the geomagnetic equator the higher the probability that afternoon TEP will occur


			{{propagation}}

TimVK4YEH: /* Why does TEP occur over the Equator? */

2008-08-16T07:49:10Z

Why does TEP occur over the Equator?

← Older revision		Revision as of 00:49, 16 August 2008
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	Evening TEP is less well understood, but is believed to ~~ely of~~ "ionospheric bubbles" - areas of high ionisation density off which signals are reflected.		Evening TEP is less well understood, but is believed to rely on "ionospheric bubbles" - areas of high ionisation density off which signals are reflected.

	==What are the characteristics of afternoon TEP?==		==What are the characteristics of afternoon TEP?==

TimVK4YEH: spelling

2008-08-15T10:01:00Z

spelling

← Older revision		Revision as of 03:01, 15 August 2008
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	Historically, the effect was first noticed in the 1940's by both military and amateur operators who discovered that it is possible to communicate in the [[VHF]] band over intercontinental distances during times of high sunspot activity.		Historically, the effect was first noticed in the 1940's by both military and amateur operators who discovered that it is possible to communicate in the [[VHF]] band over intercontinental distances during times of high sunspot activity.

	The first organised and therefore relatively large scale TEP communications occurred during 1957-1958 in the peak of sunspot cycle 19. Sunspot peaks in 1970 (cycle 20) and 1977 (cycle 21) expanded our knowledge of ~~thei~~ phenomenon.		The first organised and therefore relatively large scale TEP communications occurred during 1957-1958 in the peak of sunspot cycle 19. Sunspot peaks in 1970 (cycle 20) and 1977 (cycle 21) expanded our knowledge of the phenomenon.

	==When does TEP occur?==		==When does TEP occur?==

TimVK4YEH: spelling

2008-08-15T10:00:19Z

spelling

← Older revision		Revision as of 03:00, 15 August 2008
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	Related wiki pages: [[Bands]], [[Propagation]], [[Aurora]], [[Tropospheric ducting]], [[Lightning scatter]], [[Meteor scatter]]		Related wiki pages: [[Bands]], [[Propagation]], [[Aurora]], [[Tropospheric ducting]], [[Lightning scatter]], [[Meteor scatter]]

	Simplified ionospheric models portray the ionosphere as a series of ~~horizntal~~ layers that vary with time, location and sunspot activity. The real ionosphere is much more complex than this, particularly in in equatorial and polar regions.		Simplified ionospheric models portray the ionosphere as a series of horizontal layers that vary with time, location and sunspot activity. The real ionosphere is much more complex than this, particularly in in equatorial and polar regions.

	==What is '''T'''rans-'''E'''quatorial '''P'''ropagation (TEP)?==		==What is '''T'''rans-'''E'''quatorial '''P'''ropagation (TEP)?==

TimVK4YEH: spelling

2008-08-15T09:55:33Z

spelling

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	At the moment it is not possible to predict TEP conditions, but the following are indicative that those conditions '''may''' be possible.		At the moment it is not possible to predict TEP conditions, but the following are indicative that those conditions '''may''' be possible.

	* The receiver and transmitter should be located at equal distances from the magnetic ~~(dip)~~ equator.		* The receiver and transmitter should be located at equal distances from the magnetic equator.
	* The path must be within about 15 degrees of geomagnetic north-south.		* The path must be within about 15 degrees of geomagnetic north-south.
	* the time is around the equinoxes.		* the time is around the equinoxes.

TimVK4YEH: spelling

2008-08-15T09:55:05Z

spelling

← Older revision		Revision as of 02:55, 15 August 2008
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	==What are the characteristics of evening TEP?==		==What are the characteristics of evening TEP?==

	* Occurs around 2000 to 2300 local time, and is more frequent around the equinoxes and especially at times of high sunspot ~~number.~~		* Occurs around 2000 to 2300 local time, and is more frequent around the equinoxes and especially at times of high sunspot activity
	* Signals subject to rapid fading and strong distortion		* Signals subject to rapid fading and strong distortion
	* Signals may have doppler spread		* Signals may have doppler spread

TimVK4YEH: /* What are the characteristics of evening TEP? */

2008-08-15T09:54:30Z

What are the characteristics of evening TEP?

← Older revision		Revision as of 02:54, 15 August 2008
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	==What are the characteristics of evening TEP?==		==What are the characteristics of evening TEP?==

	* Occurs around 2000 to 2300 local time, and is more frequent around the equinoxes and		* Occurs around 2000 to 2300 local time, and is more frequent around the equinoxes and especially at times of high sunspot number.
	especially at times of high sunspot number.
	* Signals subject to rapid fading and strong distortion		* Signals subject to rapid fading and strong distortion
	* Signals may have doppler spread		* Signals may have doppler spread

TimVK4YEH: complete? needs confirmation of content

2008-08-15T09:52:48Z

complete? needs confirmation of content

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 Perhaps the most interesting of these effects is known as the "equatorial anomoly".  This occurs where a high electron concentration is found on each side of the magnetic equator, and is usually seen in the region of 10 to 20 degrees latitude.
-The afternoon TEP is believed to occur when a signal is reflected first by an anomoly on one side of the equator and then again by another anomoly on the other side.
+Afternoon TEP is believed to occur when a signal is reflected first by an anomoly on one side of the equator and then again by another anomoly on the other side.
 [[Image:Vk4yeh_TEP_1.jpg | 500px]]

TimVK4YEH: added mor info and diagram of afternoon tep

2008-08-15T09:31:55Z

added mor info and diagram of afternoon tep

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-Related wiki pages[[Bands]], [[Propagation]], [[Aurora]], [[Tropospheric ducting]], [[Lightning scatter]], [[Meteor scatter]]
+Related wiki pages: [[Bands]], [[Propagation]], [[Aurora]], [[Tropospheric ducting]], [[Lightning scatter]], [[Meteor scatter]]
 Simplified ionospheric models portray the ionosphere as a series of horizntal layers that vary with time, location and sunspot activity.  The real ionosphere is much more complex than this, particularly in in equatorial and polar regions.
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 * those occuring during late afternoon  and early evening, and usually over maximum distances of around 6000km. Contacts were restricted to the low VHF bands ([[6 metres]] for hams in most countries)
 * those occuring around 1900 to 2300 local time, with workable contacts being made on 144MHZ([[ 2 metres]]) and sometimes on 432MHz ([[70 centimetres]])