Align antenna function on NanoStation 2

[gustavosarmiento]

i've a doubt, what exactky means this function?.

[Pciena]

This function would be use if you are trying to set a point to point connection. You would have to use the Align antenna function to align one antenna to the other to maximize the throughput between the two points.

[johnhomer]

Can anyone here explain how to actually use the function?

[WHT]

The antenna align feature does not align the antenna, it is a "meter" to show if the antenna is pointed correctly.

[johnhomer]

I know that it does not align the antenna. What i want to know is how to use the tool properly. I see there's RSSI where you can move up and down. But do I i actually use it? Move the RSSI to 40 or something then align antenna manually until you get better signal? at 30RSSI, i get good signal, at 40RSSI, i get about varying signal.

As i understand it, you move the RSSI to highest possible then align antenna to find the best signal. Am i correct? no?

[WHT]

All the slider does is "center" the graph scale.

The graph is only about 20 dB wide, so it can't show all the way from -90 dBm to 0 dBm. Use the slider to center the point where you see the colors change...in the green region.

[johnhomer]

Ok I have a PtP link and i'm looking at the web interface for the station side. Opening the antenna alignment tool, I see a steady full bars (up to the BLUE section) at 30RSSI which is the default. At 30RSSI, i don't see the colored bars changing. When I bump the slider to 40RSSI, it bar starts fluctuating in the blue to green range. The question is, at this stage, should I re-align my antenna physically in such a way that I get a steady blue signal at 40RSSI? What do you mean by CENTER? Sorry I cant understand fully what you meant

The next question is, using the alignment tool, how do i know i have a perfect alignment if there is indeed what is called a perfect alignment.

The third question is, in a PtP link, from which side should i be doing Antenna Alignment? Station or AP?

TIA.

[WHT]

Hmmm...how to explain this.

First, about the colors. Red is associated with a low signal level (usually less than -80 dB) and blue is a string signal level (usually greater than -40dB).

Second, about CENTERING the slider. You want the slider adjusted such that the left half of the box has colored bars and the right half shows nothing. As you moving your antenna such that it is not pointing to the AP, then the colored bars will only show colored bars to the left. As you point closer to the AP, the colored bars will move to the right.

If for any position of the slider, you see no colored bars; move the slider to the left until you see some colored bars. If all you see are red and yellow one, then you have a weak link.

If for any position of the slider, you see the entire scale full of colors; move the slider to the right until you see the left half of the graph has colors and the right half is blank.

[Dave-D]

In a PtP link, you need to align both
antennas. The 'Align' feature shows the
signal strength as received by that unit.
For the best signal, clearly both antennas
need to be properly pointed.

You don't need to physically go to the
other end; just access its alignment
tool with your browser from one end.

Of course, there's some interaction because
both antennas are involved in both sending
and receiving. If you align one antenna
perfectly, if you then align the other antenna,
it will affect the received signal at the first one.

Be careful you begin with the antenna
pointed within a few degrees of the
proper direction. If not, you could be
aligning to a secondary lobe.

There's no such thing as a 'perfect' alignment;
you simply go for the best signal you can get. Dave

[johnhomer]

Hello WHT,

Thanks for the useful info

At 30RSSI here's what i got (see attachment 1)

At 55RSSI here's what i got (see attachment 2)

So, what does this mean? Should i re-align my antenna? Based on the colored graph, does it say something weather i should move my antenna to left or right?


How do i know when my antenna is CENTERED? when i see blue color in 55RSSI?

[Dave-D]

John, I think you've missed the point.

These antenna alignment graphs are
like the bar-graphs in your stereo:
they show the strength of the signal.

There is no way the radio can know
which way the antenna is pointed;
that's up to you. You simply rotate
the antenna left and right until you
get the best signal possible. That
will mean the antenna is centered
(pointed to the other antenna).

Do this for both antennas--on both
ends of your connection.

Your graphs show you have a quite
good signal. If it is the highest one
you can get, then you are done. Dave

[johnhomer]

Thanks dave for clarifying but you missed to explain what does the "RSSI Range" slider do.

from the AirOS Wiki

The "RSSI Range" slider bar allows the range of the meter to be either increased or reduced. If the range is reduced, the color change will be more sensitive to signal fluctuations as RSSI Range slider actually changes an offset of the maximum indicator value thus the scale itself.

So looking at my screencaps, at 30RSSI, i get blue bars (good signal) but at 55RSSI, i get a signal in the green level (middle of the graph). Question: To get proper / optimum alignment, i should leave the RSSI Range slider at 55 where the colored bar fluctuates and manually adjust my antenna in such a way that I get a signal somewhere in the blue area.

[WHT]

Back up...I think you're still not grasping this.

Let me try it this way.

The graph extends from -90 or so (the lowest receiver sensitivity) to -10 or so (the highest receiver sensitivity). That's a 90 dB spread and you can't display the whole spread at one time. Sliding the bar left or right lets you zoom in to see a 10 dB spread.

If you have blue bars, that's a good sign. Now your goal it to get those blue bars to move as far to the left as possible BY ALIGNING THE ANTENNA - NOT by moving the slider.

The ONLY thing the slider does is let you focus in on the dB range you need to look at. It DOES NOTHING to align or aim the antenna.

The optimum position of the slider bar is such that in the graph, you have colored bars on the left half of the graph and blank on the right half. Then physical move the antenna such the bars increase (move to the right side) to the point they sart to move back to the right.

[johnhomer]

Back up...I think you're still not grasping this.

Let me try it this way.

The graph extends from -90 or so (the lowest receiver sensitivity) to -10 or so (the highest receiver sensitivity). That's a 90 dB spread and you can't display the whole spread at one time. Sliding the bar left or right lets you zoom in to see a 10 dB spread.


You mean 80dB spread?

If you have blue bars, that's a good sign. Now your goal it to get those blue bars to move as far to the left as possible BY ALIGNING THE ANTENNA - NOT by moving the slider.

I'll assume you mean my ultimate goal is to get those blue bars move as far to the RIGHT by aligning the antenna.


The ONLY thing the slider does is let you focus in on the dB range you need to look at. It DOES NOTHING to align or aim the antenna.

Yes, otherwise my antenna should have came with a motor for aiming mechanism.


The optimum position of the slider bar is such that in the graph, you have colored bars on the left half of the graph and blank on the right half. Then physical move the antenna such the bars increase (move to the right side) to the point they sart to move back to the right.


This paragraph alone explained it all. Thanks WHT. You're the man.

[johnhomer]

I have written a mini how to as reference for new Ubiquiti users.

-----------------------------------------------------

Antenna Alignment Mini How-To

Purpose:

To find the best possible antenna alignment in a PtP link


Assumptions:

1. The AP and Station radios have been pre-aligned by other means such as Eye-balling, GPS, Compass + map, Google Earth, etc

2. The AP and Station radios are pre-associated, configuration on both radios are correct and the link is already online

3. You are setting up a PtP link


Steps:

Part 1 (setting UP RSSI Range)

1. Login to the administrative interface, you can find the antenna alignment tool at the Main tab in the Tools Combo box

You shoud see something like this

http://photos-e.ak.fbcdn.net/hphotos-ak-snc1/hs201.snc1/6829_1243525654779_1428500131_30711804_3331176_n.jpg

2. Move the RSSI Range slider to the right in such a way that you see colors in the LEFT half of the bar and the RIGHT half being blank as seen in the figure below.

http://photos-f.ak.fbcdn.net/hphotos-ak-snc1/hs201.snc1/6829_1243525694780_1428500131_30711805_1746510_n.jpg


Part 2 (Aligning the antenna)

3. Send someone to pan/tilt your antenna such that, colors fill the bars up to the extreme right of the bar.

Move the antenna in very small angles so that you will have time to observe the changes it will make on the colored bar. Find the highest possible signal. The best possible antenna alignment is when you see a signal in the blue area (extreme right)

http://photos-g.ak.fbcdn.net/hphotos-ak-snc1/hs229.snc1/7621_1244506199292_1428500131_30715286_2647504_n.jpg

Note: You may need to the same process on the other end of the PtP link

Links:
http://wiki.ubnt.com/wiki/index.php/AirOS
http://wiki.ubnt.com/wiki/index.php/How_to_bridge_internet_connections


Credits goes to WHT and Dave.D

[Ricardo74]

Use the RSSI in the midle range (30) and aling the antenas you are gonna see the bar enterely colored , after that use the RSSI in 55 look that the bar falls down to the midle more or less then still tryng to align the antennas when you get the bar empty the aligment is in the better way that you can get .

I did it having two bullets one in front the other and thats what i notice

Best Regards

[WHT]

I have written a mini how to as reference for new Ubiquiti users.

Credits goes to WHT and Dave.D
Ok...call me perspicacitous (well jaded if you're a red neck), but sometimes it amazes
me at the tribulations (orgasmic gyrations if you're a red neck) of aiming an antenna.

Matthew 24:21 (American Standard Version)
For then shall be great tribulation, such as hath not been from the beginning of the world until now, no, nor ever shall be.


Ok...I promise I'll stay in my corner unless called upon.