Re: [WISPA] 5.8GHz Link Loss
Guys, I think you have a classic case of multipath fading. The things to check are: 1. Is there enough fade margin to achieve the desired availability (99.98% - 99.998%)? 2. Is the first Fresnel Zone blocked 40% at K = 4/3? 3. Is the reflection point as close to one end as possible? Is it blocked? If you send me the following I will do a path analysis for you. Antenna gain at both ends, dBi Cable loss at both ends, dB Tx power output, dBm Rx sensitivity at BER = 10-6 Antenna height at both ends, AMSL in feet Path length in miles Mike -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Marlon K. Schafer Sent: Sunday, August 09, 2009 10:31 AM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss We're still guessing here. He's never told us how LONG the links are. If they are 10 miles apart it's probably not ducting. marlon - Original Message - From: Mike m...@aweiowa.com To: WISPA General List wireless@wispa.org Sent: Sunday, August 09, 2009 9:57 AM Subject: Re: [WISPA] 5.8GHz Link Loss The way I understand it, and have worked to my advantage as a ham, is the layers stratify at fairly definite borders in tropospheric ducting. The layer works more like a duct with a mirror like top. The signals can be repeatedly reflected back down into the duct. I did some experiments during one tropo opening using some long circular polarized yagis at both vhf and uhf. The signals appear to become more randomly polarized as the distance in the duct increases. The signals coming from areas around the Gulf coming into SW Fl during the events had components of both vertical and horizontal polarization. Refraction is the deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different. So, both upon entering and leaving the duct the signal can also be subject to refraction? Not sure. Mike At 10:52 AM 8/9/2009, you wrote: That is correct. So my next question: Can refraction be caused by thermal ducting? -RickG WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
One is about 18 miles, the other is just over 20 miles. - Cliff -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Marlon K. Schafer Sent: Sunday, August 09, 2009 12:31 PM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss We're still guessing here. He's never told us how LONG the links are. If they are 10 miles apart it's probably not ducting. marlon - Original Message - From: Mike m...@aweiowa.com To: WISPA General List wireless@wispa.org Sent: Sunday, August 09, 2009 9:57 AM Subject: Re: [WISPA] 5.8GHz Link Loss The way I understand it, and have worked to my advantage as a ham, is the layers stratify at fairly definite borders in tropospheric ducting. The layer works more like a duct with a mirror like top. The signals can be repeatedly reflected back down into the duct. I did some experiments during one tropo opening using some long circular polarized yagis at both vhf and uhf. The signals appear to become more randomly polarized as the distance in the duct increases. The signals coming from areas around the Gulf coming into SW Fl during the events had components of both vertical and horizontal polarization. Refraction is the deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different. So, both upon entering and leaving the duct the signal can also be subject to refraction? Not sure. Mike At 10:52 AM 8/9/2009, you wrote: That is correct. So my next question: Can refraction be caused by thermal ducting? -RickG WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database: 270.13.44/2283 - Release Date: 08/09/09 08:08:00 WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Cliff, What type of radio are you using? I have a 19.2 link over here in Gulfport and it has been rock solid. I'm using 3ft dishes too. Joe Miller DSLbyAir, LLC 228-238-2563 www.dslbyair.com - Original Message From: Cliff Leboeuf cliff.lebo...@cssla.com To: WISPA General List wireless@wispa.org Sent: Monday, August 10, 2009 8:21:16 AM Subject: Re: [WISPA] 5.8GHz Link Loss One is about 18 miles, the other is just over 20 miles. - Cliff -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Marlon K. Schafer Sent: Sunday, August 09, 2009 12:31 PM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss We're still guessing here. He's never told us how LONG the links are. If they are 10 miles apart it's probably not ducting. marlon - Original Message - From: Mike m...@aweiowa.com To: WISPA General List wireless@wispa.org Sent: Sunday, August 09, 2009 9:57 AM Subject: Re: [WISPA] 5.8GHz Link Loss The way I understand it, and have worked to my advantage as a ham, is the layers stratify at fairly definite borders in tropospheric ducting. The layer works more like a duct with a mirror like top. The signals can be repeatedly reflected back down into the duct. I did some experiments during one tropo opening using some long circular polarized yagis at both vhf and uhf. The signals appear to become more randomly polarized as the distance in the duct increases. The signals coming from areas around the Gulf coming into SW Fl during the events had components of both vertical and horizontal polarization. Refraction is the deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different. So, both upon entering and leaving the duct the signal can also be subject to refraction? Not sure. Mike At 10:52 AM 8/9/2009, you wrote: That is correct. So my next question: Can refraction be caused by thermal ducting? -RickG WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database: 270.13.44/2283 - Release Date: 08/09/09 08:08:00 WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Joe, Both links are using Radiowave 3' high performance antennas. One link is a pair of Orthogon units, the other are Trango Tlink10's and a third 20mi link are Trango Atlases. This scenario is setup as an OSPF 'ring'. Cliff -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Joe Miller Sent: Monday, August 10, 2009 8:49 AM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss Cliff, What type of radio are you using? I have a 19.2 link over here in Gulfport and it has been rock solid. I'm using 3ft dishes too. Joe Miller DSLbyAir, LLC 228-238-2563 www.dslbyair.com - Original Message From: Cliff Leboeuf cliff.lebo...@cssla.com To: WISPA General List wireless@wispa.org Sent: Monday, August 10, 2009 8:21:16 AM Subject: Re: [WISPA] 5.8GHz Link Loss One is about 18 miles, the other is just over 20 miles. - Cliff -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Marlon K. Schafer Sent: Sunday, August 09, 2009 12:31 PM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss We're still guessing here. He's never told us how LONG the links are. If they are 10 miles apart it's probably not ducting. marlon - Original Message - From: Mike m...@aweiowa.com To: WISPA General List wireless@wispa.org Sent: Sunday, August 09, 2009 9:57 AM Subject: Re: [WISPA] 5.8GHz Link Loss The way I understand it, and have worked to my advantage as a ham, is the layers stratify at fairly definite borders in tropospheric ducting. The layer works more like a duct with a mirror like top. The signals can be repeatedly reflected back down into the duct. I did some experiments during one tropo opening using some long circular polarized yagis at both vhf and uhf. The signals appear to become more randomly polarized as the distance in the duct increases. The signals coming from areas around the Gulf coming into SW Fl during the events had components of both vertical and horizontal polarization. Refraction is the deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different. So, both upon entering and leaving the duct the signal can also be subject to refraction? Not sure. Mike At 10:52 AM 8/9/2009, you wrote: That is correct. So my next question: Can refraction be caused by thermal ducting? -RickG WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database: 270.13.44/2283 - Release Date: 08/09/09 08:08:00 WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database: 270.13.44/2283 - Release Date: 08/09/09 18:10:00 WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Has the link changed completely? Or does it come and go with time of day? Are both ends of the link at the same height? If so, the reflection point will be roughly half the path. If not, the reflection point will be closer to the lower antenna. Has anything changed in the terrain at the reflection point? Are these paths urban or rural? Could there be some new growth at the reflection point? If the phenomenon has not passed, it may not be tropospheric ducting. Although ducting can persist for a day or so, if it's still degraded, probably not. If the path is over an urban are it may be Rayleigh fading, or Rician fading if the path is over trees and such. Did someone else show up and start shooting across your path, especially at mid path? There is a wealth of knowledge on this list, but we still need some more info. Did all of the 3? paths degrade similarly? Mike Both links are using Radiowave 3' high performance antennas. One link is a pair of Orthogon units, the other are Trango Tlink10's and a third 20mi link are Trango Atlases. This scenario is setup as an OSPF 'ring'. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
On Fri, Aug 07, 2009 at 10:33:37PM -0500, Ed Spoon - Computer Sales Services, Inc. wrote: So, what causes this crazy loss on all of my 'longer' 5.8 links after dark/overnight? Temp drop? Contraction? Condensation? Moonbeams? More importantly, is there anything I can do about it? Anyone else dealing with it? Links are N-S, E-W and NE-SW, different brands radios, but all in the ISM 5.8 spectrum. Can start as early as 8pm but usually after midnight. Goes until the suns been up 1 to 3 hours. Doesn't happen every day, but seems to be predominant in the summer when we get over 90 degrees with 90% humidity and then the afternoon/evening rain from the buildup. I see it happening to short links also, just doesn't get bad enough to drop. I was wondering about condensation from the evening dew in the LMR connectors which might evaporate out after a couple of hours of sunlight. Have you checked the connectors/feed horns? -- Scott LambertKC5MLE Unix SysAdmin lamb...@lambertfam.org WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
No, nothing new. This has been an ongoing issue for years. Does not last all day and does not happen every day. Can start as early as 8pm but usually after midnight. Usually gone before or just after sunrise. (Has occurred during daylight on rare occasions - I'm going to have to start a log just for this event!). Seems to be predominant in the summer. I see it happening to short links (PtMP) also, just doesn't get bad enough to drop. My gut feeling has always been that it's temperature/pressure change related. Ed On Mon, Aug 10, 2009 at 4:31 PM, Mike m...@aweiowa.com wrote: Has the link changed completely? Or does it come and go with time of day? Are both ends of the link at the same height? If so, the reflection point will be roughly half the path. If not, the reflection point will be closer to the lower antenna. Has anything changed in the terrain at the reflection point? Are these paths urban or rural? Could there be some new growth at the reflection point? If the phenomenon has not passed, it may not be tropospheric ducting. Although ducting can persist for a day or so, if it's still degraded, probably not. If the path is over an urban are it may be Rayleigh fading, or Rician fading if the path is over trees and such. Did someone else show up and start shooting across your path, especially at mid path? There is a wealth of knowledge on this list, but we still need some more info. Did all of the 3? paths degrade similarly? Mike Both links are using Radiowave 3' high performance antennas. One link is a pair of Orthogon units, the other are Trango Tlink10's and a third 20mi link are Trango Atlases. This scenario is setup as an OSPF 'ring'. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
That is correct. So my next question: Can refraction be caused by thermal ducting? -RickG On Sat, Aug 8, 2009 at 1:27 PM, Faisal Imtiazfai...@snappydsl.net wrote: LOL... I believe RickG is trying to point out that the correct word is Refraction and not Scintillation.. Jack U. can add his comments into this Heat Humidity cause Refraction to radio waves, ...that is why in long links they use Diversity Antenna Arrays. Regards Faisal Imtiaz -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Mike Sent: Saturday, August 08, 2009 1:05 PM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss Scintillation, for our purposes, is similar to when you see a mirage on a highway in front of you, usually on a hot day, and not uncommon across deserts. The wavering of the light waves is the same thing that happens to radio signals, more-or-less. I once had a canopy, with dish mounted on a high roof shooting across a white flat roof. After the install, the customer would drop lots of packets. We moved it 4 feet higher to change the angle of incidence and it stayed stable. That's one reason all of this seems black magic at times. Regarding the tropo propagation, as a ham radio operator, at times the uhf and vhf bands would open from SW FL all the way across the Gulf of Mexico and we could talk to hams in Texas, Alabama, Louisiana and others at times. Many times this went on for hours and sometimes days. At 10:19 AM 8/8/2009, you wrote: Which definition of scintillation applies? * Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. en.wikipedia.org/wiki/Scintillation_(astronomy) * scintillate - twinkle: emit or reflect light in a flickering manner; Does a constellation twinkle more brightly than a single star? WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Can refraction be caused by thermal ducting? -RickG --- And the answer is Absolutely YES . !! Faisal Imtiaz -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of RickG Sent: Sunday, August 09, 2009 11:52 AM To: fai...@snappydsl.net; WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss That is correct. So my next question: Can refraction be caused by thermal ducting? -RickG On Sat, Aug 8, 2009 at 1:27 PM, Faisal Imtiazfai...@snappydsl.net wrote: LOL... I believe RickG is trying to point out that the correct word is Refraction and not Scintillation.. Jack U. can add his comments into this Heat Humidity cause Refraction to radio waves, ...that is why in long links they use Diversity Antenna Arrays. Regards Faisal Imtiaz -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Mike Sent: Saturday, August 08, 2009 1:05 PM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss Scintillation, for our purposes, is similar to when you see a mirage on a highway in front of you, usually on a hot day, and not uncommon across deserts. The wavering of the light waves is the same thing that happens to radio signals, more-or-less. I once had a canopy, with dish mounted on a high roof shooting across a white flat roof. After the install, the customer would drop lots of packets. We moved it 4 feet higher to change the angle of incidence and it stayed stable. That's one reason all of this seems black magic at times. Regarding the tropo propagation, as a ham radio operator, at times the uhf and vhf bands would open from SW FL all the way across the Gulf of Mexico and we could talk to hams in Texas, Alabama, Louisiana and others at times. Many times this went on for hours and sometimes days. At 10:19 AM 8/8/2009, you wrote: Which definition of scintillation applies? * Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. en.wikipedia.org/wiki/Scintillation_(astronomy) * scintillate - twinkle: emit or reflect light in a flickering manner; Does a constellation twinkle more brightly than a single star? -- -- WISPA Wants You! Join today! http://signup.wispa.org/ -- -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ -- -- WISPA Wants You! Join today! http://signup.wispa.org/ -- -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
So, it would be good to pay attention to the thermal ducting reports as another tool towards a better understanding of issues with your network? -RickG On Sun, Aug 9, 2009 at 12:02 PM, Faisal Imtiazfai...@snappydsl.net wrote: Can refraction be caused by thermal ducting? -RickG --- And the answer is Absolutely YES . !! Faisal Imtiaz -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of RickG Sent: Sunday, August 09, 2009 11:52 AM To: fai...@snappydsl.net; WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss That is correct. So my next question: Can refraction be caused by thermal ducting? -RickG On Sat, Aug 8, 2009 at 1:27 PM, Faisal Imtiazfai...@snappydsl.net wrote: LOL... I believe RickG is trying to point out that the correct word is Refraction and not Scintillation.. Jack U. can add his comments into this Heat Humidity cause Refraction to radio waves, ...that is why in long links they use Diversity Antenna Arrays. Regards Faisal Imtiaz -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Mike Sent: Saturday, August 08, 2009 1:05 PM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss Scintillation, for our purposes, is similar to when you see a mirage on a highway in front of you, usually on a hot day, and not uncommon across deserts. The wavering of the light waves is the same thing that happens to radio signals, more-or-less. I once had a canopy, with dish mounted on a high roof shooting across a white flat roof. After the install, the customer would drop lots of packets. We moved it 4 feet higher to change the angle of incidence and it stayed stable. That's one reason all of this seems black magic at times. Regarding the tropo propagation, as a ham radio operator, at times the uhf and vhf bands would open from SW FL all the way across the Gulf of Mexico and we could talk to hams in Texas, Alabama, Louisiana and others at times. Many times this went on for hours and sometimes days. At 10:19 AM 8/8/2009, you wrote: Which definition of scintillation applies? * Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. en.wikipedia.org/wiki/Scintillation_(astronomy) * scintillate - twinkle: emit or reflect light in a flickering manner; Does a constellation twinkle more brightly than a single star? -- -- WISPA Wants You! Join today! http://signup.wispa.org/ -- -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ -- -- WISPA Wants You! Join today! http://signup.wispa.org/ -- -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
On long links the information could help you explain some anomalies. From an engineering point of view space diversity is the best way to cope with tropospheric ducting. To a lesser extent, frequency diversity can help maintain a long link since different frequencies are affected slightly differently by the duct. An apt metaphor is two different sized flat rocks will exhibit different skip patterns as they are launched across a pond. At 11:51 AM 8/9/2009, you wrote: So, it would be good to pay attention to the thermal ducting reports as another tool towards a better understanding of issues with your network? -RickG WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
We're still guessing here. He's never told us how LONG the links are. If they are 10 miles apart it's probably not ducting. marlon - Original Message - From: Mike m...@aweiowa.com To: WISPA General List wireless@wispa.org Sent: Sunday, August 09, 2009 9:57 AM Subject: Re: [WISPA] 5.8GHz Link Loss The way I understand it, and have worked to my advantage as a ham, is the layers stratify at fairly definite borders in tropospheric ducting. The layer works more like a duct with a mirror like top. The signals can be repeatedly reflected back down into the duct. I did some experiments during one tropo opening using some long circular polarized yagis at both vhf and uhf. The signals appear to become more randomly polarized as the distance in the duct increases. The signals coming from areas around the Gulf coming into SW Fl during the events had components of both vertical and horizontal polarization. Refraction is the deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different. So, both upon entering and leaving the duct the signal can also be subject to refraction? Not sure. Mike At 10:52 AM 8/9/2009, you wrote: That is correct. So my next question: Can refraction be caused by thermal ducting? -RickG WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Ed, Are these PTP or PTMP links? I have a couple of my PTP links do this also. Mainly around the Mobile county AL area. It appears that the noise floor increases at night. The two common things between our areas is that it is a coastal area and close to the oil and gas fields. Joe Miller DSLbyAir, LLC 228-238-2563 - Original Message From: Ed Spoon - Computer Sales Services, Inc. ed.sp...@cssla.com To: wireless@wispa.org Sent: Friday, August 7, 2009 10:33:37 PM Subject: [WISPA] 5.8GHz Link Loss So, what causes this crazy loss on all of my 'longer' 5.8 links after dark/overnight? Temp drop? Contraction? Condensation? Moonbeams? More importantly, is there anything I can do about it? Anyone else dealing with it? Links are N-S, E-W and NE-SW, different brands radios, but all in the ISM 5.8 spectrum. Can start as early as 8pm but usually after midnight. Goes until the suns been up 1 to 3 hours. Doesn't happen every day, but seems to be predominant in the summer when we get over 90 degrees with 90% humidity and then the afternoon/evening rain from the buildup. I see it happening to short links also, just doesn't get bad enough to drop. Ideas?[image: 2009-08-07_221007.jpg] Ed Spoon triparish.net / cajun.net Computer Sales Services, Inc. Ph: 985-879-3219 / Fax: 985-876-6789 PRIVILEGED AND CONFIDENTIAL COMMUNICATION This electronic transmission and any documents attached hereto may contain confidential and/or legally privileged information. The information is intended only for use by the recipient named above. If you have received this electronic message in error please notify the sender and delete the electronic message. Any disclosure, copying, distribution, or use of the contents of information received in error or otherwise is strictly prohibited. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
We're seeing almost exactly the same thing on one of our 5.8GHz VL links (could be PTMP but at the moment is just PTP) a little north of NYC. We know we have a multipath issue at the site to begin with, and the fresnel zone is just grazing some trees. I suspect that the humidity / temp combination is causing some distortion of the fresnel zone with respect to the trees. In our case, the environmental changes may be impacting the multipath as well. Tricky to troubleshoot. Here's a note from a list member from a year or so ago that may be relevant: /What is actually happening is the K value of the path is changing when you get hot air under cool dense air. The normal value of refraction (ie K) is 4/3 and approaches 2 on coastal areas. Well when you have a link where K goes down to 2/3 or less it causes the earth profile to bulge out and obstruct the path. This with decoupling (only an issue with high gain antennas) where the angle of the incoming wave is greater then the beam width of the antenna feed will cause outage. At this distance you should be running at a 33 or so SNR with no interference. Now when the signal fades you loose your signal and have to compete even more with the interfering signal. might want to try another polarization and HP antennas./ Thanks, Adam On 8/8/2009 7:59 AM, Joe Miller wrote: Ed, Are these PTP or PTMP links? I have a couple of my PTP links do this also. Mainly around the Mobile county AL area. It appears that the noise floor increases at night. The two common things between our areas is that it is a coastal area and close to the oil and gas fields. Joe Miller DSLbyAir, LLC 228-238-2563 - Original Message From: Ed Spoon - Computer Sales Services, Inc. ed.sp...@cssla.com To: wireless@wispa.org Sent: Friday, August 7, 2009 10:33:37 PM Subject: [WISPA] 5.8GHz Link Loss So, what causes this crazy loss on all of my 'longer' 5.8 links after dark/overnight? Temp drop? Contraction? Condensation? Moonbeams? More importantly, is there anything I can do about it? Anyone else dealing with it? Links are N-S, E-W and NE-SW, different brands radios, but all in the ISM 5.8 spectrum. Can start as early as 8pm but usually after midnight. Goes until the suns been up 1 to 3 hours. Doesn't happen every day, but seems to be predominant in the summer when we get over 90 degrees with 90% humidity and then the afternoon/evening rain from the buildup. I see it happening to short links also, just doesn't get bad enough to drop. Ideas?[image: 2009-08-07_221007.jpg] Ed Spoon triparish.net / cajun.net Computer Sales Services, Inc. Ph: 985-879-3219 / Fax: 985-876-6789 PRIVILEGED AND CONFIDENTIAL COMMUNICATION This electronic transmission and any documents attached hereto may contain confidential and/or legally privileged information. The information is intended only for use by the recipient named above. If you have received this electronic message in error please notify the sender and delete the electronic message. Any disclosure, copying, distribution, or use of the contents of information received in error or otherwise is strictly prohibited. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
On Sat, Aug 8, 2009 at 12:33 AM, Ed Spoon - Computer Sales Services, Inc.ed.sp...@cssla.com wrote: So, what causes this crazy loss on all of my 'longer' 5.8 links after dark/overnight? Temp drop? Contraction? Condensation? Moonbeams? Likely to be scintillation. Rubens WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Recently we had a tropospheric ducting episode which affected ever 2.4 p2mp customers. There was a layer of warmer air actually trapped by a layer of cooler air. This junction looks like a mirror to radio waves and can be steered or bounced quite a bit off target. When I built microwave links in S FL that had to be very reliable, we engineered for space diversity. One 22 mile link at 6GHz used pairs of dishes with 30' separation. It would switch many times in a year, and during tropo events, several times in one night. Gulf areas are more apt to see tropo events. Here in the midwest they are uncommon. This may not be the case with your link, but is worth learning about. Here is a nice site for tropo predictions. http://www.dxinfocentre.com/tropo_car.html Mike At 10:33 PM 8/7/2009, you wrote: So, what causes this crazy loss on all of my 'longer' 5.8 links after dark/overnight? Temp drop? Contraction? Condensation? Moonbeams? More importantly, is there anything I can do about it? Anyone else dealing with it? Links are N-S, E-W and NE-SW, different brands radios, but all in the ISM 5.8 spectrum. Can start as early as 8pm but usually after midnight. Goes until the suns been up 1 to 3 hours. Doesn't happen every day, but seems to be predominant in the summer when we get over 90 degrees with 90% humidity and then the afternoon/evening rain from the buildup. I see it happening to short links also, just doesn't get bad enough to drop. Ideas?[image: 2009-08-07_221007.jpg] Ed Spoon triparish.net / cajun.net Computer Sales Services, Inc. Ph: 985-879-3219 / Fax: 985-876-6789 PRIVILEGED AND CONFIDENTIAL COMMUNICATION This electronic transmission and any documents attached hereto may contain confidential and/or legally privileged information. The information is intended only for use by the recipient named above. If you have received this electronic message in error please notify the sender and delete the electronic message. Any disclosure, copying, distribution, or use of the contents of information received in error or otherwise is strictly prohibited. Content-Type: image/jpeg; name=2009-08-07_221007.jpg Content-ID: ii_122f807387d6193a X-Attachment-Id: ii_122f807387d6193a WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
At 08:18 AM 8/8/2009, you wrote: Likely to be scintillation. Could be, but in my experience, scintillation is more of a factor mid day. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
We see sort of the opposite. Better signal levels at night. I think the consensus was it's directly related to the temperature of the radio. [image: bh.png] On Fri, Aug 7, 2009 at 9:33 PM, Ed Spoon - Computer Sales Services, Inc. ed.sp...@cssla.com wrote: So, what causes this crazy loss on all of my 'longer' 5.8 links after dark/overnight? Temp drop? Contraction? Condensation? Moonbeams? More importantly, is there anything I can do about it? Anyone else dealing with it? Links are N-S, E-W and NE-SW, different brands radios, but all in the ISM 5.8 spectrum. Can start as early as 8pm but usually after midnight. Goes until the suns been up 1 to 3 hours. Doesn't happen every day, but seems to be predominant in the summer when we get over 90 degrees with 90% humidity and then the afternoon/evening rain from the buildup. I see it happening to short links also, just doesn't get bad enough to drop. Ideas?[image: 2009-08-07_221007.jpg] Ed Spoon triparish.net / cajun.net Computer Sales Services, Inc. Ph: 985-879-3219 / Fax: 985-876-6789 PRIVILEGED AND CONFIDENTIAL COMMUNICATION This electronic transmission and any documents attached hereto may contain confidential and/or legally privileged information. The information is intended only for use by the recipient named above. If you have received this electronic message in error please notify the sender and delete the electronic message. Any disclosure, copying, distribution, or use of the contents of information received in error or otherwise is strictly prohibited. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ bh.png WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
How long is longer? I've also seen usage kill links. If those are pings it could also be that just the pings are getting dropped but traffic is flowing fine. marlon - Original Message - From: Ed Spoon - Computer Sales Services, Inc. ed.sp...@cssla.com To: wireless@wispa.org Sent: Friday, August 07, 2009 8:33 PM Subject: [WISPA] 5.8GHz Link Loss So, what causes this crazy loss on all of my 'longer' 5.8 links after dark/overnight? Temp drop? Contraction? Condensation? Moonbeams? More importantly, is there anything I can do about it? Anyone else dealing with it? Links are N-S, E-W and NE-SW, different brands radios, but all in the ISM 5.8 spectrum. Can start as early as 8pm but usually after midnight. Goes until the suns been up 1 to 3 hours. Doesn't happen every day, but seems to be predominant in the summer when we get over 90 degrees with 90% humidity and then the afternoon/evening rain from the buildup. I see it happening to short links also, just doesn't get bad enough to drop. Ideas?[image: 2009-08-07_221007.jpg] Ed Spoon triparish.net / cajun.net Computer Sales Services, Inc. Ph: 985-879-3219 / Fax: 985-876-6789 PRIVILEGED AND CONFIDENTIAL COMMUNICATION This electronic transmission and any documents attached hereto may contain confidential and/or legally privileged information. The information is intended only for use by the recipient named above. If you have received this electronic message in error please notify the sender and delete the electronic message. Any disclosure, copying, distribution, or use of the contents of information received in error or otherwise is strictly prohibited. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Which definition of scintillation applies? Definitions of scintillation on the Web: * (physics) a flash of light that is produced in a phosphor when it absorbs a photon or ionizing particle * twinkle: a rapid change in brightness; a brief spark or flash * a brilliant display of wit * glitter: the quality of shining with a bright reflected light * the twinkling of the stars caused when changes in the density of the earth's atmosphere produce uneven refraction of starlight wordnetweb.princeton.edu/perl/webwn * Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. en.wikipedia.org/wiki/Scintillation_(astronomy) * Scintillating scotoma is the most common visual aura preceding migraine and was first described by 19th century physician Hubert Airy (1838–1903). en.wikipedia.org/wiki/Scintillation_(medicine) * Scintillation is a fluctuation in the amplitude of a target on a radar display. It is closely related to target glint, or wander, an apparent displacement of the target from its mean position. ... en.wikipedia.org/wiki/Scintillation_(radar) * Scintillation is a flash of light produced in a transparent material by an ionization event. See scintillator and scintillation counter for ... en.wikipedia.org/wiki/Scintillation_(physics) * A flash of light; a spark; The twinkling of a star caused by turbulence in the Earth's atmosphere; The flash of light produced by a phosphor ... en.wiktionary.org/wiki/scintillation * scintillate - give off; the substance scintillated sparks and flashes * scintillate - sparkle: reflect brightly; Unquarried marble sparkled on the hillside * scintillate - twinkle: emit or reflect light in a flickering manner; Does a constellation twinkle more brightly than a single star? * scintillate - physics: fluoresce momentarily when struck by a charged particle or high-energy photon; the phosphor fluoresced wordnetweb.princeton.edu/perl/webwn * scintillating - brilliantly clever; scintillating wit; a play full of scintillating dialogue wordnetweb.princeton.edu/perl/webwn On Sat, Aug 8, 2009 at 9:18 AM, Rubens Kuhlrube...@gmail.com wrote: On Sat, Aug 8, 2009 at 12:33 AM, Ed Spoon - Computer Sales Services, Inc.ed.sp...@cssla.com wrote: So, what causes this crazy loss on all of my 'longer' 5.8 links after dark/overnight? Temp drop? Contraction? Condensation? Moonbeams? Likely to be scintillation. Rubens WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Ha! I looked up scintillation as well and was wondering the same thing. Odds are Mike hit it on the head with the RF thermal ducting suggestion. We've seen this on long paths (20miles+) that have little down tilt. The RF signal can be ducted away from the intended target as it gets caught between thermal layers in the atmosphere. Paths with more down tilt between point A and point B appear to be more resilient to RF thermal ducting. I can only assume this is because the RF signal has a better chance of pushing through the thermal duct wall err I mean ceiling floor. Long paths engineered with enough fade margin will typically stay up, but may downshift in modulation to compensate for the reduced signal strength. This is why it is important to eek out every last db of signal when first installing long PtP paths. Best, Brad -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of RickG Sent: Saturday, August 08, 2009 10:20 AM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss Which definition of scintillation applies? Definitions of scintillation on the Web: * (physics) a flash of light that is produced in a phosphor when it absorbs a photon or ionizing particle * twinkle: a rapid change in brightness; a brief spark or flash * a brilliant display of wit * glitter: the quality of shining with a bright reflected light * the twinkling of the stars caused when changes in the density of the earth's atmosphere produce uneven refraction of starlight wordnetweb.princeton.edu/perl/webwn * Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. en.wikipedia.org/wiki/Scintillation_(astronomy) * Scintillating scotoma is the most common visual aura preceding migraine and was first described by 19th century physician Hubert Airy (1838-1903). en.wikipedia.org/wiki/Scintillation_(medicine) * Scintillation is a fluctuation in the amplitude of a target on a radar display. It is closely related to target glint, or wander, an apparent displacement of the target from its mean position. ... en.wikipedia.org/wiki/Scintillation_(radar) * Scintillation is a flash of light produced in a transparent material by an ionization event. See scintillator and scintillation counter for ... en.wikipedia.org/wiki/Scintillation_(physics) * A flash of light; a spark; The twinkling of a star caused by turbulence in the Earth's atmosphere; The flash of light produced by a phosphor ... en.wiktionary.org/wiki/scintillation * scintillate - give off; the substance scintillated sparks and flashes * scintillate - sparkle: reflect brightly; Unquarried marble sparkled on the hillside * scintillate - twinkle: emit or reflect light in a flickering manner; Does a constellation twinkle more brightly than a single star? * scintillate - physics: fluoresce momentarily when struck by a charged particle or high-energy photon; the phosphor fluoresced wordnetweb.princeton.edu/perl/webwn * scintillating - brilliantly clever; scintillating wit; a play full of scintillating dialogue wordnetweb.princeton.edu/perl/webwn On Sat, Aug 8, 2009 at 9:18 AM, Rubens Kuhlrube...@gmail.com wrote: On Sat, Aug 8, 2009 at 12:33 AM, Ed Spoon - Computer Sales Services, Inc.ed.sp...@cssla.com wrote: So, what causes this crazy loss on all of my 'longer' 5.8 links after dark/overnight? Temp drop? Contraction? Condensation? Moonbeams? Likely to be scintillation. Rubens WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Scintillation, for our purposes, is similar to when you see a mirage on a highway in front of you, usually on a hot day, and not uncommon across deserts. The wavering of the light waves is the same thing that happens to radio signals, more-or-less. I once had a canopy, with dish mounted on a high roof shooting across a white flat roof. After the install, the customer would drop lots of packets. We moved it 4 feet higher to change the angle of incidence and it stayed stable. That's one reason all of this seems black magic at times. Regarding the tropo propagation, as a ham radio operator, at times the uhf and vhf bands would open from SW FL all the way across the Gulf of Mexico and we could talk to hams in Texas, Alabama, Louisiana and others at times. Many times this went on for hours and sometimes days. At 10:19 AM 8/8/2009, you wrote: Which definition of scintillation applies? * Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. en.wikipedia.org/wiki/Scintillation_(astronomy) * scintillate - twinkle: emit or reflect light in a flickering manner; Does a constellation twinkle more brightly than a single star? WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
LOL... I believe RickG is trying to point out that the correct word is Refraction and not Scintillation.. Jack U. can add his comments into this Heat Humidity cause Refraction to radio waves, ...that is why in long links they use Diversity Antenna Arrays. Regards Faisal Imtiaz -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Mike Sent: Saturday, August 08, 2009 1:05 PM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss Scintillation, for our purposes, is similar to when you see a mirage on a highway in front of you, usually on a hot day, and not uncommon across deserts. The wavering of the light waves is the same thing that happens to radio signals, more-or-less. I once had a canopy, with dish mounted on a high roof shooting across a white flat roof. After the install, the customer would drop lots of packets. We moved it 4 feet higher to change the angle of incidence and it stayed stable. That's one reason all of this seems black magic at times. Regarding the tropo propagation, as a ham radio operator, at times the uhf and vhf bands would open from SW FL all the way across the Gulf of Mexico and we could talk to hams in Texas, Alabama, Louisiana and others at times. Many times this went on for hours and sometimes days. At 10:19 AM 8/8/2009, you wrote: Which definition of scintillation applies? * Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. en.wikipedia.org/wiki/Scintillation_(astronomy) * scintillate - twinkle: emit or reflect light in a flickering manner; Does a constellation twinkle more brightly than a single star? WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] 5.8GHz Link Loss
Scintillation effects cause the radio signals to be refracted. Scintillation is a real world concern for those building microwave links *ESPECIALLY* if the scintillation off of a warm surface is in the fresnel zone of the link, like in my install over a flat roof. The dish was at least 10 feet off the surface of that roof, but shooting over probably 300 feet of flat rubber membrane. Scintillation every afternoon trashed the link until we raised the dish a few feet. At 12:27 PM 8/8/2009, you wrote: LOL... I believe RickG is trying to point out that the correct word is Refraction and not Scintillation.. Jack U. can add his comments into this Heat Humidity cause Refraction to radio waves, ...that is why in long links they use Diversity Antenna Arrays. Regards Faisal Imtiaz -Original Message- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Mike Sent: Saturday, August 08, 2009 1:05 PM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss Scintillation, for our purposes, is similar to when you see a mirage on a highway in front of you, usually on a hot day, and not uncommon across deserts. The wavering of the light waves is the same thing that happens to radio signals, more-or-less. I once had a canopy, with dish mounted on a high roof shooting across a white flat roof. After the install, the customer would drop lots of packets. We moved it 4 feet higher to change the angle of incidence and it stayed stable. That's one reason all of this seems black magic at times. Regarding the tropo propagation, as a ham radio operator, at times the uhf and vhf bands would open from SW FL all the way across the Gulf of Mexico and we could talk to hams in Texas, Alabama, Louisiana and others at times. Many times this went on for hours and sometimes days. At 10:19 AM 8/8/2009, you wrote: Which definition of scintillation applies? * Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. en.wikipedia.org/wiki/Scintillation_(astronomy) * scintillate - twinkle: emit or reflect light in a flickering manner; Does a constellation twinkle more brightly than a single star? WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
