Diddy1
join:2003-07-19
Sidney, NE
| [Tech Ops] Antenna alignment
When initially aligning antennas, what methods to some of you use for "eye-balling"? Of course after rough in alignment, one always fine tunes via readings off the device, but getting a good "eyeballed" shot helps initially.
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if you fail to plan, you plan to fail |
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shorthairedp
join:2005-11-21
Pontiac, IL | if you use a link estimator tool using gps coordinates, youll get a reading you can point to using a compass, this is pretty accurate |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
 ·WaveCrazy.Net
| said by shorthairedp  :if you use a link estimator tool using gps coordinates, youll get a reading you can point to using a compass, this is pretty accurate Agreed. The compass and GPS will get you close, but the rest is all trial and error. Get a Sharpie and make a mark on your mount so you have a reference point. Then I always go left to right and mark that. I then go up and down until it gets the best link. I then mark that point with the Sharpie again, that way you have a reference point if you have to swap out the unit or make any other changes. 
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»www.wavecrazy.net
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AMD Phreak
Please do the needfull
Premium
join:2003-12-14
edit:
July 2nd, @11:30PM
| Depends on the path length. Close in links I eyeball by standing behind the antenna and looking down the path. Then I look from the side and guesstimate the elevation. Once that is done I fine tune using the software or multimeter RSI.
On dishes, we hook up a gunscope if the path is a long one. The gunscope mounts where the feedhorn is supposed to go. This allows us a true "boresight" alignment. These long paths also get a back-azimuth done as well before starting this process.
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"No job is so important, and no service is so urgent that we cannot take the time to do it safely."
-- AT&T
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it." |
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funkyfelty
Armament For Peace
join:2002-10-01
Lebanon, PA | reply to Diddy1
another way is lasers and strobe lights. have used strobe lights for roof top alignments and a few tower alignments
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Soldier, Firefighter, Proud to be an American |
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markscs
join:2003-03-14
Wingham, ON
| reply to Diddy1
What has worked for me is to put a wide-beamed sector at one end, and then go to the other end and aim up your high-gain antenna.
After that you have one link you know is aimed properly.
Then go back and replace the sector with another high gain antenna and move it around until you hit the other end.
YMMV... |
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cmaenginsb
Premium,MVM
join:2001-03-19
Palmdale, CA
| reply to Diddy1
I've done links at 30 miles + using nothing more than the GPS coordinates of the site and Topousa to align 4' dishes. Being it gets foggy here there is no line of sight method to align with.
The basic method is to plot the link in the topo program to get an azimuth. Look at the elevation differences to estimate up/downtilt. I'd go to the site and perform initial alignment. After that I would tweak the dishes to peak out RSSI.
Generally we are within 2-3 db of peak just by using the compass. As stated you can do this even if it is too cloudy/dark to make the alignment. I looked into the riflescope idea but never had the time to make the adapter for it.
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CCNA, Comtrain Certified Tower Climber |
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AMD Phreak
Please do the needfull
Premium
join:2003-12-14
| It takes time to do the riflescope.
We get bad inversions here in the summer time when most of the antenna work is done so we use every method that we can to align antennas, especially on those links that must aim out of the valley and up to the hill. |
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Diddy1
join:2003-07-19
Sidney, NE | AMD Phreak, please elaborate on inversions? I've heard this before, but maybe you could enlighten us all on this?
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if you fail to plan, you plan to fail |
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public
join:2002-01-19
Santa Clara, CA
 ·DSL EXTREME
| said by Diddy1 :AMD Phreak, please elaborate on inversions? I've heard this before, but maybe you could enlighten us all on this? Thermal inversion bends signals including microwave like a mirage. The antenna is effectively pointed elsewhere. |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
·WaveCrazy.Net
| said by public :said by Diddy1 :AMD Phreak, please elaborate on inversions? I've heard this before, but maybe you could enlighten us all on this? Thermal inversion bends signals including microwave like a mirage. The antenna is effectively pointed elsewhere. A good example of this is looking down a long asphalt road on a really hot summer day. If you have ever noticed, the road looks shiny out in the distance. This is because heat is distorting the light, causing a ripple like effect on what you see.
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»www.wavecrazy.net
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Diddy1
join:2003-07-19
Sidney, NE | How does one determine if the "inversion" effect is occuring, other than the antenna needing to be aimed off from it's recieving side?
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if you fail to plan, you plan to fail |
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AMD Phreak
Please do the needfull
Premium
join:2003-12-14
| I was speaking more along the lines of the inversion causing visual alignment problems during initial aiming. It does also however create problems like you all are speaking about, however those issues can be directly combated with higher fade margins. |
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cmaenginsb
Premium,MVM
join:2001-03-19
Palmdale, CA
| reply to Diddy1
said by Diddy1 :How does one determine if the "inversion" effect is occuring, other than the antenna needing to be aimed off from it's recieving side? I remember one long link (40 miles +) over a valley that would show a 30 db fade during the inversions that happened over the valley. |
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Diddy1
join:2003-07-19
Sidney, NE | And how did you conclude it was "inversions" that caused the fade?
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if you fail to plan, you plan to fail |
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AMD Phreak
Please do the needfull
Premium
join:2003-12-14
| You can determine if it is the cause of fade by watching the signal strengths throughout the day. You'll see the RSL go from the nominal level to below nominal to garbage (if you didn't plan enough fade!), back up to nominal.
This is why it is so important to monitor your PTP links. The longer you monitor them for the more of a trend you can see. I see wild swings in spring and summer, occasionally in the winter.
--
"No job is so important, and no service is so urgent that we cannot take the time to do it safely."
-- AT&T
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it." |
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cmaenginsb
Premium,MVM
join:2001-03-19
Palmdale, CA | reply to Diddy1
As AMD Phreak states we monitored the links and were able to co-relate the signal dips with the times an inversion layer was present over the valley. |
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markscs
join:2003-03-14
Wingham, ON
| reply to Diddy1
So is anyone using a GPS with built in electronic compass? Garmin and Magellan make a couple, I was thinking that might be kind of handy for really long links. Looking for recommendations... thinking Garmin Vista or Magellan Triton 500.
Most GPSs have compass but you have to move for them to work, my understanding is an electronic compass in the GPS works standing still so you could input the co-ordinates of your endpoint and it should basically point to where you need to aim the antenna? |
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Mad Dawg
Mad Dawg
Premium
join:2006-03-19
edit:
July 5th, @12:26AM
| reply to Diddy1
I have found gps units even the expensive compass ones to be rather disappointing I have a seven hundred dollar one with the digital compass that is sitting here collecting dust
Personally I find a good old fashion compass and a 10 buck degree gauge from home depot works most efficeintly
I have made 59km FD links first try using this method :
I walk out 50 or so feet on my compass bearing and make a mark walk out another 100 or 200 feet and make another mark and then align visually from the tower using those marks
its crude but effective  and cheap lol
If you want a really pro tool I would say look at a combo unit sighting compass /inclinometer similar to this one
»www.geo-tools.com/tandem.htm
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Best Regards
MD |
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