Fade Mechanisms - Revision history

Chrisg at 16:10, 26 February 2020

2020-02-26T16:10:40Z

Chrisg at 16:10, 26 February 2020

2020-02-26T16:10:10Z

Chrisg at 15:42, 26 February 2020

2020-02-26T15:42:42Z

Cassieg at 18:29, 21 February 2020

2020-02-21T18:29:14Z

Cassieg at 18:28, 21 February 2020

2020-02-21T18:28:32Z

Cassieg at 18:26, 21 February 2020

2020-02-21T18:26:17Z

Cassieg at 18:25, 21 February 2020

2020-02-21T18:25:05Z

Cassieg at 18:19, 21 February 2020

2020-02-21T18:19:24Z

Cassieg: Created page with "=Fade Mechanisms= Microwave fades fall into the following categories: * Multipath fading * Obstruction fading * Fading due to a specular reflection * Ducting and propagation ..."

2020-02-21T18:19:12Z

Created page with "=Fade Mechanisms= Microwave fades fall into the following categories: * Multipath fading * Obstruction fading * Fading due to a specular reflection * Ducting and propagation ..."

New page

=Fade Mechanisms=
Microwave fades fall into the following categories:

* Multipath fading
* Obstruction fading
* Fading due to a specular reflection
* Ducting and propagation anomalies
* Rain fading (above ~ 8 GHz)

With the exception of rain fading, microwave fading only
depends on the change of the refractive index with height
along the path

{| class="wikitable" style="display: inline-table;"
|+
|-
! Availability
! Seconds
! Minutes
! Hours
|-
|99%
|315360
|5256
|87.6
|-
|99.9%
|31536
|525
|8.76
|-
|99.99%
|3153
|52.5
|0.876
|-
|99.999%
|315
|5.3
|0.088
|}

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← Older revision		Revision as of 18:29, 21 February 2020
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	* Fades which last less than 10 consecutive seconds are classed as severely errored seconds (SES).		* Fades which last less than 10 consecutive seconds are classed as severely errored seconds (SES).
	* Fades which last longer than 10 consecutive seconds are classed as unavailability. All rain fades are considered as unavailability.		* Fades which last longer than 10 consecutive seconds are classed as unavailability. All rain fades are considered as unavailability.
		+
		+	Note that Pathloss program can predict the time duration of multipath fades and separate the fades into SES and unavailability; however this is not used.
		+	By convention multipath fades are always classed as SES.
		+
		+	On SDH radio systems two additional parameters are used:
		+
		+	* severely errored seconds ratio (SESR)
		+	* background block error rate (BBER)

@@ Line 59: / Line 59: @@
 Multipath fades on a link are not correlated. The total time below level due to multipath, is the sum of the outage times in each direction.
 Rain fades affect both directions of transmission equally.
 Therefore, the total time below level for rain and multipath is the sum of the multipath outage time in each direction plus the outage time due to rain.
 European Telecommunications Standards Institute (ETSI)

@@ Line 43: / Line 43: @@
-Link Performance Definition
+==Link Performance Definition==
 The definition of link performance only considers multipath and rain fades.
 This implies the following assumptions:
@@ Line 50: / Line 51: @@
 * signal nulls due to a specular reflection are small com-pared to the fade margin or a space diversity configura-tion has been implemented.
 * the probability of ducting is unknown.

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		+	Link Performance Definition
		+	The definition of link performance only considers multipath and rain fades.
		+	This implies the following assumptions:
		+
		+	* the path has sufficient clearance / fade margin to obviate the possibility of an obstruction fade.
		+	* signal nulls due to a specular reflection are small com-pared to the fade margin or a space diversity configura-tion has been implemented.
		+	* the probability of ducting is unknown.

← Older revision		Revision as of 18:19, 21 February 2020
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−	~~=Fade Mechanisms=~~	+
	Microwave fades fall into the following categories:		Microwave fades fall into the following categories: