if you want to understand the science behind it .. here is an excellent paper discussing all aspects ...
https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet70/oet70a.pdf The reason I called your observation anecdotal because a lot of key important information is missing from your statement, and there is a lot of 'assumed' / presumed information left to the readers imagination. Let me try to explain it further .. You are comparing to radios of different bands, with different TX powers, Different RX Gain Antennas, on two links, without any confirmation of your signal levels, rain fade loss, alignment, actual modulation drop etc etc etc .. and you are making a statement that higher freq is more stable at a shorter link than a lower freq on a longer link (which by itself as a general statement would be true, however you are expounding it by stretching both freq links to be of a size that will be affected by Rain Fade, regardless). Now if you were to actually look and understand the science behind it all, you will quickly find that your observation is in direct conflict of actual science, for the two links your are actually comparing.. Thus leading to a logical conclusion that in your observation, there is some other factor (such as the ones I mentioned above) must be creating the observed behavior. (and we are not even going to into the discussion of 'rain drop size, density, and even spread across any particular region). Thus , I refer to your observation as being anecdotal ! :) :) Faisal Imtiaz Snappy Internet & Telecom http://www.snappytelecom.net Tel: 305 663 5518 x 232 Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net > From: "Rory Conaway" <r...@triadwireless.net> > To: af@afmug.com > Sent: Sunday, January 21, 2018 6:51:34 PM > Subject: Re: [AFMUG] Quick comparison between 80GHz and AF24 > What are you talking about, anecdotal? I’ll provide more complete information > for you then. > I’ve got 5 AF24 links in the same area with varying distances from 800’ > (although that one was replaced with a B5-Lite last year) to 2.47 miles. The > only one that goes down is the 2.47 mile link and even then it’s about twice a > year for about 20 minutes during monsoon season. I think I have some pretty > objective data since they are all within 3 miles. I don’t have a 2.5 mile > 80GHz > link in that area so no effort was made to compare. The 2 mile link on this > particular 5-hop system has not gone down. This has been up for 2 years so we > have 2 summers of monsoon data. > Rory > From: Af [mailto:af-boun...@afmug.com] On Behalf Of Faisal Imtiaz > Sent: Sunday, January 21, 2018 1:46 PM > To: af@afmug.com > Subject: Re: [AFMUG] Quick comparison between 80GHz and AF24 >>> I’ve got an AF24 that will drop at 2.5 miles for about an hour a year. I’ve >>> got > >> a 39GHz link at 2 miles that seems pretty solid also > This is exactly the type of anecdotal observations that I made reference to > earlier :) > Regards. > Faisal Imtiaz > Snappy Internet & Telecom > http://www.snappytelecom.net > Tel: 305 663 5518 x 232 > Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net >> From: "Rory Conaway" < r...@triadwireless.net > >> To: af@afmug.com >> Sent: Saturday, January 20, 2018 2:02:53 PM >> Subject: Re: [AFMUG] Quick comparison between 80GHz and AF24 >> I’m in Southern Arizona so heavy rain is pretty brief but also why I’m asking >> the question. I’ve got an AF24 that will drop at 2.5 miles for about an hour >> a >> year. I’ve got a 39GHz link at 2 miles that seems pretty solid also but I’m >> open to using that at 3.5 if that has a better chance too. >> Rory >> From: Af [ mailto:af-boun...@afmug.com ] On Behalf Of Mike Hammett >> Sent: Saturday, January 20, 2018 11:07 AM >> To: af@afmug.com >> Subject: Re: [AFMUG] Quick comparison between 80GHz and AF24 >> Trango's initial 24 GHz radio could do that. >> ----- >> Mike Hammett >> Intelligent Computing Solutions >> Midwest Internet Exchange >> The Brothers WISP >> From: "Mathew Howard" < mhoward...@gmail.com > >> To: "af" < af@afmug.com > >> Sent: Saturday, January 20, 2018 12:04:15 PM >> Subject: Re: [AFMUG] Quick comparison between 80GHz and AF24 >> This is the first I've heard of adaptive channel sizes... I've been looking >> at >> both Siklu and Bridgewater, and nobody from either company ever mentioned >> that >> (that doesn't necessarily mean they can't do it though). >> On Jan 20, 2018 11:58 AM, "Mike Hammett" < af...@ics-il.net > wrote: >> Adaptive channel sizes? >> ----- >> Mike Hammett >> Intelligent Computing Solutions >> Midwest Internet Exchange >> The Brothers WISP >> From: "Eric Kuhnke" < eric.kuh...@gmail.com > >> To: af@afmug.com >> Sent: Saturday, January 20, 2018 11:48:24 AM >> Subject: Re: [AFMUG] Quick comparison between 80GHz and AF24 >> This is not extremely new in 80 GHz, just with different and denser >> modulations. >> The Siklu 80 GHz stuff has done adaptive coding and modulation for a while. >> The >> (now 7 year old!) Bridgewave adaptrate 80 GHz stuff would maintain a 100 Mbps >> link during a rain fade, by switching a nominally QPSK-modulated 1500 MHz >> wide >> channel for 1 Gbps, temporarily down to BPSK during a rain fade event. >> On Sat, Jan 20, 2018 at 9:45 AM, Stefan Englhardt < s...@genias.net > wrote: >>> Some vendors do some new things to stretch the range of 80GHz: >>> http://de.nec.com/de_DE/global/prod/nw/pasolink/products/ipasolinkEX_advanced.html >>> ? >>> They modulate down and then reduce channel size. >>> This gear is in the 20kEuro Range … >>> Von: Af [mailto: af-boun...@afmug.com ] Im Auftrag von Faisal Imtiaz >>> Gesendet: Samstag, 20. Januar 2018 17:08 >>> An: af@afmug.com >>> Betreff: Re: [AFMUG] Quick comparison between 80GHz and AF24 >>> We have two things to contend with... >>> one is Oxygen Absorption >>> second is Rain Fade >>> Science says, 24ghz has much less O2 absorption fade vs 80ghz >>> Science also says that 24ghz has slightly less Rain fade vs 80ghz >>> Science also says that if on a particular link, if one is comparing 24ghz vs >>> 80ghz, the difference in which link drops first will be based on the TX >>> power / >>> Antenna Gain and Rx sensitivity. >>> If all things were exactly the same, then 80ghz would drop before 24ghz in >>> Rain >>> event. >>> But in reality, all things are not the same.. I believe 80ghz one is allowed >>> more power, and higher antenna gain. >>> https://www.e-band.com/index.php?id=86 >>> https://www.linkedin.com/pulse/dont-fall-siklu-overbuilds-distance-claims-david-theodore >>> at 3.5miles, one is pushing the limits of both 24gzh as well as 80ghz.. >>> Depending on what you are trying to achieve, and the rainzone, you can make >>> your choice based on what will perform better normally... cause both of them >>> will go out in rain :) >>> Best of Luck >>> Faisal Imtiaz >>> Snappy Internet & Telecom >>> http://www.snappytelecom.net >>> Tel: 305 663 5518 x 232 >>> Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net >>>> From: "Mathew Howard" < mhoward...@gmail.com > >>>> To: "af" < af@afmug.com > >>>> Sent: Friday, January 19, 2018 8:42:31 PM >>>> Subject: Re: [AFMUG] Quick comparison between 80GHz and AF24 >>>> I'd guess 24ghz would be slightly better, but either one is going to drop >>>> at >>>> that distance if you ever get heavy rain. >>>> Somebody from Siklu told me at one time, that some of their customers have >>>> told >>>> then that their rainfade is slightly better than an AF24, but slightly >>>> worse >>>> than an AF24HD... how accurate that is, I don't know. >>>> On Jan 19, 2018 6:03 PM, "Rory Conaway" < r...@triadwireless.net > wrote: >>>>> I haven’t run the numbers so please save me some time. Which one has less >>>>> fade >>>>> margin at 3.5 miles? I was going to use Siklu with a 2’ antenna. >>>>> Rory Conaway • Triad Wireless • CEO >>>>> 4226 S. 37 th Street • Phoenix • AZ 85040 >>>>> 602-426-0542 >>>>> r...@triadwireless.net >>>>> www.triadwireless.net >>>>> “"Engineers believe that if it ain't broke, it doesn't have enough >>>>> features >>>>> yet." — Scott Adams
