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Topic: Fade margin

	Fading
		In telecommunications, fading is a change in the attenuation of a communications channel.
		The term "backhoe fade" is used humorously to describe the complete loss of signal that occurs in a communications cable when it is cut by a backhoe or other digging work.
		Backhoe fade is one of the most common causes of failure in subterranean cables.
	www.brainyencyclopedia.com /encyclopedia/f/fa/fading.html (165 words)

	MoPro Chapter 12.7
		The large range in the fades are caused by such factors as variable density of foliage cutting the earth-satellite path, bearing to the satellite, blockage effects due to roadside obstacles and the presence of underpasses.
		Alternate suggested fade margin levels may be obtained using the indicated EERS values that are representative of roadside tree shadowing where the tree density exceeds 55%.
		Table 12-3: Fade level ranges at the 1% and 10% probabilities derived from measured distributions which were culled in terms of frequency and elevation angle.
	www.utexas.edu /research/mopro/chapter12/chapter12-7.htm (237 words)

	MoPro Chapter 6.5
		Figure 6-8 shows that for any given fade margin, the effect of the antenna separation is dramatic the first 2 meters, whereas at larger spacing, relatively little additional fade reduction ensues.
		The major fading for "expressway" measurements was observed to depend primarily on the density of overpasses.
		Table 6-4 summarizes the fading and diversity gain results for the Kan-etsu Expressway and the trunk road which correspond to measurements at an elevation angle of 46° to 47°.
	www.utexas.edu /research/mopro/chapter06/chapter06-5.htm (1131 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		Start with the fade margin value you found for the inbound uplink in Question #1, and determine the operating point of the transponder, by establishing the input back off in the uplink rain fade.
		Thus the uplink rain attenuation margin is 8.9 dB.
		The uplink C/N in a 5.4 dB rain fade is 20 - 5.4 = 14.6 dB.
	www.ee.vt.edu /~ee5656/solutions/E5698H5S.DOC (1638 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		The fade margin is the amount of "extra" signal that is present between 2 antennae.
		Fade margin can be calculated during system design and measured during system installation.
		Because fade margin can be measured, it is possible to install wireless links that are extremely reliable,even exceeding the reliability of a wired link.
	www.ghana.net /faq.html (857 words)

	Reseau Citoyen: AppendixE
		Fade margin is the difference, in dB, between the magnitude of the received signal at the receiver input and the minimum level of signal determined for reliable operation.
		The exact amount of fade margin required depends on the desired reliability of the link, but a good rule-of-thumb is 20 to 30 dB.
		Fade margin is often referred to as "thermal" or "system operating margin".
	reseaucitoyen.be /index.php?AppendixE (943 words)

	Rain Attenuation on Ku-Band and C-Band Satellite Transmissions (Site not responding. Last check: 2007-10-22)
		The rain fade margin is the amount of extra power Telesat adds to the signal strength to compensate for the possibility of rain attenuation.
		This margin is the amount of extra transmission power of signal strength Telesat provides so your service is not affected by rain attenuation during normal rainfalls.
		The rain fade margin is a component of the link margin, and is a calculation of expected rain attenuation over one year.
	www.telesat.ca /satellites/transmissions/rain-attenuation.htm (901 words)

	Designing MIMO systems for Reliable Coverage in Non-LOS Wireless Links
		The fade margin traces shown in the following plots are selected as a result of many simulations such that 99.9% link availability is guaranteed based on outages lasting less than 10 seconds.
		Basically, figure 8 describes the particular fade margin traces are chosen such that 99.9 percent availability is guaranteed based on less than a 10 second outage.
		Margins are further reduced by up to 5 dB with the three receive-antenna array gain and the two transmit-antenna array gain.
	rfdesign.com /mag/radio_designing_mimo_systems_2/index.html (3378 words)

	Marc's Technical Pages: Radio Telemetry - On the Edge ! (Site not responding. Last check: 2007-10-22)
		Fading is as a result of particles obstructing the radio signals e.g.
		Fading is not as a result of obstructions such as buildings; that is path loss.
		Fade is the extra loss through the effects of elements on a pre-determined path loss.
	www.marcspages.co.uk /rtc/0334.htm (239 words)

	MoPro Chapter 7.9
		We emphasize here again that the extent of fading is dependent on frequency, elevation angle, bearing to the satellite, the density of foliage cutting the earth-satellite path, and the offset of trees from the road.
		Also affecting the fading are scattering and blockage effects from telephone poles, street signs, and underpasses.
		Alternate suggested fade margin levels may be obtained using the indicated EERS values which are dominantly representative of roadside tree shadowing where the trees density exceeds 55%.
	www.utexas.edu /research/mopro/chapter07/chapter07-9.htm (213 words)

	Soft Handoffs in CDMA Mobile Systems
		It has been argued that the system fade margin for hard handoff is larger than the corresponding value for soft handoff in an identical environment with identical service requirements, and therefore using soft handoff leads to performance improvement.
		After running simulations in different conditions with varying propagation parameters, it is concluded that the difference in required fade margin for IS-95 CDMA and GSM is about 3 dB, slightly higher than what their rough analysis indicates (2 dB), and slightly lower than the results from the analysis of [15].
		A disadvantage of using hysteresis is that the handoff decision is delayed, and this delay increases with hysteresis margin.
	www.comsoc.org /pci/private/1997/dec/Wong.html (9845 words)

	An Introduction to Microwave System Design (Site not responding. Last check: 2007-10-22)
		Fade Margin is the difference between the unfaded Receive Signal Level and the Receiver Sensitivity Threshold.
		Fade Margin is the linkand#8217;s insurance against unexpected system outages.
		Fade Margin is directly related to Link Availability, which is the percentage of time that the link is functional.
	www.proxim.com /support/all/stratum/technotes/tn2001-08-13a.html (3097 words)

	Dictionary and Encyclopedia - "F" Listings
		The Fade Margin is an additional level of required signal strength assumed during the design of a wireless network that provides an allowance for signal strength fading in the final installed network.
		This design allowance provides sufficient system gain or sensitivity to ensure that the required quality of service is maintained even if environmental noise, co-channel interference, reflection, refraction, diffraction, or other signal attenuation issues are present.
		A firewall is that part of a computer network that implements and enforces an access control (or security) policy between two networks.
	www.connect802.com /encyclopedia/enc-f.htm (694 words)

	Using attenuators to determine fade margin
		If you make a measurement when the propagation conditions are excellent and find that your fade margin is only a few decibels, then you may have a complete loss of signal under poor conditions.
		The amount of attenuation switched in is equal to the fade margin of the system at that particular location.
		Telephone line margin Attenuators can be used in a similar manner to check the safety margin on a remote-control line provided by the telco.
	mrtmag.com /mag/radio_using_attenuators_determine/index.html (1133 words)

	Link Analysis
		The Coaxial Cable length is 1 meter (3.28 feet) for all devices except TOTAL where cable length is 0 meter/feet.
		Fade Margin is a design allowance that provides for sufficient system sensitivity to accommodate expected fading, for the purpose of ensuring that the required quality of service is maintained and is expressed as power in dB.
		Fading is caused by changes in the characteristics of the propagation path with time.
	www.smartbridges.com /showcase/link.php (78 words)

	Effect of Channel Assignment
		M is the fade margin given in Figure 4.
		The differences between equations (1) and (la) are in noise bandwidth (4.2 vs. 6 MHz), CNR (28 vs. 16dB) and fade margin (90 vs 99%).
		The differential fade margin, M(99)-M(90), is (from Figure 4) approximately 7.5dB at 56 miles for antenna height of 1200' above the average terrain.
	www.sonic.net /~aluther/paper1994.html (2025 words)

	Overview of Techniques for Mitigation of Fading And Shadowing in the Mobile Direct Broadcast Satellite Environment. (Site not responding. Last check: 2007-10-22)
		Thus shadowing is the dominant signal impairment and fading effects are again found to be relatively flat for a large fading margin.
		The combination of fade and non-fade duration statistics are commonly used to characterize the temporal nature of signal fading in the mobile channel.
		Figure 3a shows the joint fading statistic P2(,Z) averaged over the entire 45 minute run and parameterized on the allowed fade margin Z. At a time offset equal to zero, the y-axis value is the overall sample probability, P1(Z), that the signal fade exceeds the fade margin.
	yreka.stanford.edu /~djulian/Papers/prop3.html (6738 words)

	Site Surveys and Path Loss for Microwave Paths in the Fort Berthold Reservation
		Assuming we have a clear shot with the AGL needed on both ends, with 8' dishes we would have a fade margin of 16.3 dB and an uptime of 99.925831% or outages totaling 389.83 minutes a year as there is a some distance on this link.
		Assuming we have a clear shot with the AGL needed on both ends, with 8' dishes we would have a fade margin of 16.3 dB and an uptime of 99.669931% or outages totaling 1,734.84 minutes a year as there is a some distance on this link.
		If we reduced this to 6' dishes the fade margin would be 13.7dB with an uptime of 99.950711% or outage of 259.06 minutes per year.
	www.lns.com /projects/AN-MSI/Ft_Berthold/pathloss_report.html (1391 words)

	Broadcast Engineering: Digital STLs (Site not responding. Last check: 2007-10-22)
		You have to include those losses in the overall path loss or the fade margin isn't going to be what you expected.
		A design fade margin of 40dB is still desirable.
		A good fade margin with high reliability is still a must, whether you're dealing with analog or digital signals.
	www.findarticles.com /p/articles/mi_m0CVJ/is_6_46/ai_n6081445 (846 words)

	Feedback
		In the core of his argument, Guill states that "spread-spectrum manufacturers recommend that 30dB and not less than 20dB of the available fade margin be reserved for override interference." I can say with some certainty that he is not representing my company or the practical experience of unlicensed spread-spectrum radio users.
		The steady-state background noise level can be determined from field fade margin measurements, and no correlation between interference and fading is likely when directional antennas are used.
		So, all of the available margin may be allocated for multi-path fading, unless the specific site conditions dictate otherwise.
	wirelessreview.com /mag/wireless_feedback_10 (663 words)

	Alloy Computer Products - Technical Support (Site not responding. Last check: 2007-10-22)
		The Operating System Margin calculator can be used to determine whether or not your wireless network will function correctly over a required distance.
		If the Operating System Margin is a negative value then your wireless network will not work.
		The Fade Margin is the amount of signal above the sensitivity of your receiver that should be received in order to insure a stable, high quality link during inclement weather and atmospheric disturbances.
	www.alloy.com.au /support.asp?TID=235 (273 words)

	sara-glo (Site not responding. Last check: 2007-10-22)
		Where the repeater is the centre hub and the spokes are the incoming signals.
		Any number of drop repeaters can be linked to a hub repeater, providing the path from the source to the hub site meets the required fade margin.
		The fade margin is simply, the amount of signal that is required under any propagation variable to make a reliable point to point contact.
	saralink.ca /sara-glo.htm (592 words)

	Kings Contgrol Rain Shield / Fade satellite dish solution
		This loss of signal is commonly referred to as “rain fade” or signal attenuation.
		In many cases, the loss of signal strength due to rain is not more than the rain fade margin, so you can still be watching TV when it rains.
		You lose picture when there is enough water in the atmosphere to completely block the signal, or more likely when the signal loss caused by a combination of water in the atmosphere and water on the dish and LNB exceed the rain fade margin.
	www.sadoun.com /Sat/Products/kings-control/Rain-Shield-Fade-Solution.htm (705 words)

	Fade margin -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-22)
		Fade margin -- Facts, Info, and Encyclopedia article
		In ((often plural) systems used in transmitting messages over a distance electronically) telecommunication, the term fade margin (fading margin) has the following meanings:
		The amount by which a received signal level may be reduced without causing system performance to fall below a specified (The smallest detectable sensation) threshold value.
	www.absoluteastronomy.com /encyclopedia/f/fa/fade_margin.htm (73 words)

	RACES ATV PATH PROFILE CALCULATIONS (Site not responding. Last check: 2007-10-22)
		Note that the shorter path still doesn't afford any margin for fade.
		So far it looks like the paths are at or below 0db fade margin (figuring a potential fade of 40db).
		Please note that none of the paths checked using free space path loss seem to have a comfortable fade margin.
	www.qsl.net /n6lv/RACES (506 words)

	RA 374- Frequency Assignment Criteria
		In order to calculate the required fade margin for a particular percentage of time (unavailability) an iteration process is required.
		If this percentage time is too large then the fade depth is increased and the process repeats until a figure for fade depth relating to the percentage of time required is obtained to within 0.1dB.
		the fade depth is too high) then the calculation process is repeated for a fade depth equal to the mean between the last two figures.
	www.ofcom.org.uk /static/archive/ra/publication/fac/ra374/ra374.htm (3599 words)

	MaxStream.net - Long Range Radio Modem
		RF transmission range is all about how many dB of fade margin are present in the system.
		Fade margin of a wireless connection where 20 dBm of transmit power is emitted to a yagi antenna with 6 dBi gain, and the signal received by a 6dBi gain yagi antenna connected to a receiver with -90 dBm receive sensitivity with a total path loss of 150 dB, equals
		That is a whopping 20 dB difference in fade margin.
	www.maxstream.net /spotlight/long-range.php (575 words)

	ULS tutorial
		In certain parts of the United States the path must be designed with extra fade margin to offset heavy rain or heavy snow conditions.
		Minimum receiver signal strength for maximum allowable noise performance is available from the equipment manufacturer and must be used for setting the allowable fade margin.
		At this point, the STL path is configured and you are certain it has adequate fade margin.
	www.munn-reese.com /ULS1.htm (5064 words)

	UHF/VHF Link Budget (Site not responding. Last check: 2007-10-22)
		TAP will calculate a thermal fade margin based on the received signal level, receiver threshold, predicted transmission loss and other factors described in this tutorial.
		You may, for example, wish to contrast the fade margin calculations of both an optimistic and pessimistic path configuration by creating and saving two link budget path records for the same link.
		A Thermal Fade Margin ("TFM") is calculated as the Received Signal Level less the receiver Threshold in dBm.
	www.softwright.com /faq/support/vhf_uhf_link_budget.html (2880 words)

	RF System Analysis (Site not responding. Last check: 2007-10-22)
		This page can then be used to determine the entire system losses and gains for an ultimate calculation of available signal and fade margin.
		The higher this signal is above the minimum value expected the more "Fade Margin" the system has.
		The longer the path the greater will be the fading and therefore the greater the "recommended Fade Margin" must be to counteract the fading.
	www.v-soft.com /PlotPath/t6.htm (555 words)

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