February 2013 - PSDR - mailman.hamwan.org

annoying banter...
by Rob Salsgiver 07 Feb '13

07 Feb '13

Sorry all for the ongoing barrage of emails, but once something starts taking root in the head it's hard to drive it out... Has there been any thought given to the angle of marketing HamWAN to repeater owners? Specifically the following two points: 1) Internet based remote control for repeaters 2) Internet connectivity for repeaters (echolink, IRLP, D-Star gateways, etc) Getting mountain-top connections to the 'net is often difficult enough. If we market right, we may be able to get into sites easier, connect to multiple repeaters per site, make their lives easier, and drive some adoption and expansion through that avenue. Cheers, Rob

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Improved radiation pattern software and new antennas on the way
by Bart Kus 07 Feb '13

07 Feb '13

Hello, I've taken some time tonight to improve the radiation pattern measurement software. The algorithm for auto-centering the rotation of the pattern won't be fooled now by the presence of a non-centered peak lobe. Full description of the software function and the software itself have both been published to the Antenna Analysis <https://www.hamwan.org/t/tiki-index.php?page=Antenna+Analysis&structure=Ham…> labs page. The radiation pattern for the Laid sector <https://www.hamwan.org/t/tiki-index.php?page=Laird+SAH58-120-16-WB&structur…> has been updated and you can see the wonky alignment is now gone! Since neither of these antennas are thrilling performers in the HamWAN Labs tests, a couple more candidates have been added to the Sector Antenna - 120deg <https://www.hamwan.org/t/tiki-index.php?page=Sector+Antenna+-+120deg&struct…> component engineering page. A HamWAN community member who wishes to remain anonymous has generously purchased sample antennas of the Teletronics and RF Elements brands for lab testing. They should arrive some time next week. In the meantime, I've had a thought about how to improve F/B ratios in these sector antennas. Using a sheet of aluminum and my sheet metal brake <http://www.harborfreight.com/30-inch-bending-brake-67240.html>, I should be able to manufacture traditional RF shields, like this: VARIA 14-19dBi variable sector antenna 45-120°, 2.4-2.5GHz but without fancy holes or adjustable features. It might be enough to keep that nasty high power adjacent RF out. --Bart

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IP space plan
by Rob Salsgiver 07 Feb '13

07 Feb '13

Greetings all, I may have missed this somewhere on the site, but is there an IP plan yet? Are we looking to use 44 net space, or something else? Cheers, Rob

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high gain antennas...
by Rob Salsgiver 07 Feb '13

07 Feb '13

Looking over some of the antenna selection stuff and came across this at quite a lower price point than the ARC dish at about $75 less. It is 28-30.25 db vs 34 (typical), and has a 5 degree beam width vs 4. Max vswr is 1.4 though, compared to 1.8 (1.5 norm) for the ARC. Not sure what else I'm missing. http://dl.ubnt.com/Rocket_Dish5G-30.pdf

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New Dev Team member
by Bart Kus 06 Feb '13

06 Feb '13

Hello, I'm pleased to announce HamWAN's first Dev Team member, Rob Salsgiver (NR3O)! He'll join the likes of myself (AE7SJ), Curt Black (WR5J) and Benjamin Krueger (N2IHK) in dedicating part of his life to make HamWAN's vision a reality for the Puget Sound. --Bart

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Updated antenna radiation pattern software + some more readings
by Bart Kus 05 Feb '13

05 Feb '13

Hello, So I've improved the radiation pattern software to automatically: 1) Normalize the graphs to 0dB 2) Rotate the peak amplitude to the 0 degree position 3) Find the -3dB power points and calculate beamwidth 4) Measure the -120 and +120 degree power levels (adjacent antenna interference angles) 5) Detect the angular measurement resolution 6) Generate R-code for graphing 7) Spit out all the numerical details that belong with the pretty picture Using this wonderful new automation (so easy to do now!) I put the ARC Wireless "variable sector" "120 degree" antenna through its various settings. The results are on the antenna's lab page: https://www.hamwan.org/t/tiki-index.php?page=ARC+ARC-VS5818SD1&structure=Ha… The bogosity of "variable sector" is visible as the radiation pattern hardly budges between 60deg, 90deg and 120deg adjustment positions. This a fixed 60 degree sector antenna as far as I can tell. If HamWAN was using 6-sector cells it would be perfect. Next I re-ran the measurements on the Laird, with the results updated on the antenna's lab page: https://www.hamwan.org/t/tiki-index.php?page=Laird+SAH58-120-16-WB&structur… Pretty good show, just like last time. A calculated 3dB beamwidth of 111 degrees is a lot closer to the 120 deg spec than the ARC Wireless. The +/- 120 deg rejection though could be nasty in real life. Gotta check it out without all these echoes. One obvious thing is that the graph isn't centered correctly. This is because the centering/rotation algorithm aligns the 0 deg mark with the maximum signal reading over the whole pass. In this case, that was an off-center lobe on the front face of the antenna. I need to re-work the auto-centering so that it uses the -3dB points instead and centers right in the middle of them. But tomorrow, too tired tonight. In short, the sector antenna story is sucking. We need good + cheap sector antennas for this thing to work! The Laird is $180/ea with questionable +/- 120 deg rejection. --Bart

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Re: [PSDR] Spectrum allocation for point-to-multipoint sectorized cell sites published
by Bart Kus 04 Feb '13

04 Feb '13

+PSDR List The same page that has the generic ring also has the more realistic map, lower down. It includes Scott's Paine Field site. Sugarloaf will likely be replaced by "Baldi" Mtn (Grass Mtn). I'm not crazy about the Graham Hill ground bounce site. Is there anything with elevation around there we can use to bridge Baldi+Capitol? Given the spacing between the sites I don't think we need to worry about PtMP frequency mapping too much. The same sectors (azimuth+freq) can and should be used at each site. The only problem to solve would be the coordination of PtP link freqs between the sites, but that won't be a real problem until there's plenty of sites. :) The modems don't have automatic adaptive power, so if that's needed (and I don't think it will be), it would have to be coded by us. There are no active sites right now. I'm plowing through antenna testing as fast as I can before site deploys. I'm working with Cougar Mtn mgmt to make that the first high site. Then Paine Field will be the first long distance link of about 25 miles, very shortly after. Do you have LoS to Cougar? The question level is good. It's exactly the stuff we need to be worrying about right now. All the cyberspace/networking stuff can be changed from the comfort of our desks, but to change out antenna or radio hardware after it's been installed on a commercial tower is a much larger headache. --Bart On 2/3/2013 9:48 PM, Rob Salsgiver wrote: > > Ok. Just got done doing some catch-up reading on the site..... > > Do we have an updated "map" -- even on a theoretical basis? I see the > generic ring on the site, and I know Scott Honaker had a few potential > center nodes filled in on a hand-sketch at one time -- I think mainly > because it was Snohomish DEM was looking to be one of the possible > inner link sites. > > The topic below begs for a map to better understand. At first blush, > it would seem that the higher power amateur links would fit most > nicely with any longer distance backhaul requirements -- i.e. -- if we > had a link that needed to go from one end to the other North to > South. Some of the lower power U-NII -- as you noted, for closer > links. Once we start penciling in some starting frequency and channel > assignments -- even on a "theoretical" map, I think it will let us > "see" some of the more obvious problems and additional questions that > might need to be asked. We may re-use U-NII frequencies on the north > and south ends, as long as they don't have any likely hood for direct > or even tropo RF shadows or ducting / overlaps. These temperature > inversions we have can be a potentially big headache to deal with as > well. Power might need to be adaptive based on rain or fog, or even > if we start to get indications of multipath. > > Let me know if we have a better map to work with, or if you want me to > start keeping notes and throwing some working materials together. > > Do we have any active high-sites at the moment for experimenting? > > Sorry if it's too much or too many stupid questions -- unfortunately > that's what you get when my brain starts following new rabbits down > the path...<g> > > Cheers, > > Rob > > *From:*PSDR [mailto:psdr-bounces@hamwan.org] *On Behalf Of *Bart Kus > *Sent:* Sunday, February 03, 2013 2:38 PM > *To:* psdr(a)hamwan.org > *Subject:* [PSDR] Spectrum allocation for point-to-multipoint > sectorized cell sites published > > Hello, > > I've just published the proposed PtMP spectrum usage for HamWAN cell > sites. It can be seen at the Spectrum Allocation > <https://www.hamwan.org/t/tiki-index.php?page=Spectrum+Allocation&structure=…> > page. Optimized for viewing @ 2560x1600. :) The point-to-point links > between cell sites will not be allocated/planned before hand, and > don't need to be published since no users will use those links. > > Any objections/suggestions? > > My biggest worry right now is when someone wants to use the ARC 34dBi > dish to link to a sector, but the dish's frequency response may suck > that high up. The 21dBi grids seem to only lose 3dB of gain from > their peak at the very top of the spectrum. Not awful. Have not yet > measured the 27dBi grids, but expect similar results. > > One very important thing this plan does is identify the center working > frequency for the sector antennas as being 5.855GHz. That's the > frequency at which radiation pattern measurements should be made, and > is the very next task on my list. > > --Bart >

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[PSDR] PRELIMINARY Azimuth radiation patterns published
by Bart Kus 04 Feb '13

04 Feb '13

I've rigged up a good-enough blend of hardware and software to measure antenna radiation patterns. As a test run of the setup I've measured the azimuth response of the 2 sectors antennas I have in stock here. Results published on their individual antenna pages: https://www.hamwan.org/t/tiki-index.php?page=ARC+ARC-VS5818SD1&structure=Ha… https://www.hamwan.org/t/tiki-index.php?page=Laird+SAH58-120-16-WB&structur… Please heed the published warnings+instructions there. The environment is full of reflections and the measurements are wildly inaccurate because of this, especially at 0 degrees (back turned towards RF source). Signals are bouncing off the metal in my patio door. But despite all the shortcomings of this new system, it does reveal some interesting things. For example, I'm willing to bet $100 that the ARC Wireless antenna will NEVER read as a 120deg sector, even when measured in proper conditions. The front lobe is just too damn narrow. Hell, it'll have a hard time pretending to be even a 90deg sector! Manufacturer nonsense like this is why it's so important to measure your gear before deploying into the real world. This measurement system can also be used to measure elevation radiation patterns, and cross polarization. Hurray for progress! :) --Bart

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[PSDR] Spectrum allocation for point-to-multipoint sectorized cell sites published
by Bart Kus 03 Feb '13

03 Feb '13

Hello, I've just published the proposed PtMP spectrum usage for HamWAN cell sites. It can be seen at the Spectrum Allocation <https://www.hamwan.org/t/tiki-index.php?page=Spectrum+Allocation&structure=…> page. Optimized for viewing @ 2560x1600. :) The point-to-point links between cell sites will not be allocated/planned before hand, and don't need to be published since no users will use those links. Any objections/suggestions? My biggest worry right now is when someone wants to use the ARC 34dBi dish to link to a sector, but the dish's frequency response may suck that high up. The 21dBi grids seem to only lose 3dB of gain from their peak at the very top of the spectrum. Not awful. Have not yet measured the 27dBi grids, but expect similar results. One very important thing this plan does is identify the center working frequency for the sector antennas as being 5.855GHz. That's the frequency at which radiation pattern measurements should be made, and is the very next task on my list. --Bart

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[PSDR] Sector antenna frequency response curves published!
by Bart Kus 03 Feb '13

03 Feb '13

Hello, After way too many side-quests, I've finally managed to measure the frequency response curves of the 2 top sector antenna candidates. The measurements were made using a higher precision technique than originally published for antenna frequency response measurement. The software to help the measurements has also been updated. The improved precision technique is in the last section of the Antenna Analysis page: https://www.hamwan.org/t/tiki-index.php?page=Antenna+Analysis&structure=Ham… The ARC ARC-VS5818SD1 sector antenna FR curve is linked at the top of the above page, but can be directly viewed here: https://www.hamwan.org/t/tiki-index.php?page=ARC+ARC-VS5818SD1&structure=Ha… The Laird SAH58-120-16-WB sector antenna FR curve is also linked at the top of the Antenna Analysis page, but here you go: https://www.hamwan.org/t/tiki-index.php?page=Laird+SAH58-120-16-WB&structur… The figure of merit in these tests is low variability. A constant gain across the whole spectrum is ideal. Next up, I need to build an antenna rotor system and do radiation pattern measurements. This is gonna be tough. Anybody wanna donate an AZ/EL rotor? Or any decent computer-controlled rotor? --Bart

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