Need tips for improving signal of 4 mile WDS link

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JofCore
DD-WRT Novice


Joined: 24 Apr 2007
Posts: 38
Location: Farmland, MI

PostPosted: Thu Sep 30, 2010 3:10    Post subject: Need tips for improving signal of 4 mile WDS link Reply with quote
I am trying to set up a 4 mile WDS link and I've got the link up enough for the radios to see each other, but my signal is still kinda weak enough that I'm seeing significant packet loss.

Here's my setup:

WRT54GL on each end (12548M NEWD Eko)
(mounted outside on antenna pole w/external enclosure)
24dbi grid antenna
aprox 4 miles between antennas; one end is pretty open and clear, but the other end does have some trees around it.
The antennas are mounted on the roof of each building (2 story house height) on a 5 ft-ish pole.
so shooting through some tree tops.

I was aiming the antennas by reading the wireless status info from dd-wrt and got to where things seemed better, but still pretty bad. Then I started tinkering with the channel and the TX power. When I switched from Ch1 to Ch11 the signal improved, and I turned up the Xmit power all the way and that also improved my signal.

However, it's still not good enough for a solid connection.

the signal as DD-WRT reports it is something like:
signal noise SNR strength
-82 -67 -15 14%
-81 -69 -12 16%

So at this point I'm wondering if I would need some sort of wifi amplifier to get my link usable (something like http://www.ayagroup.com/product.php?productid=17203);

or do I need to try to fine tune my antenna aim now that I have the power all the way up?

Any thought, suggestions, etc appreciated :)

thx

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JofCore
DD-WRT Novice


Joined: 24 Apr 2007
Posts: 38
Location: Farmland, MI

PostPosted: Thu Sep 30, 2010 17:21    Post subject: Reply with quote
Oh, I forgot to mention; those signal readings above are from the end w/out the trees. (also, I forgot to mention that I am currently running w/out encryption just to try to establish the signal)

On the far end (with trees), the signal isn't as good(I don't have access to it right now, so I'm going from memory...), only around 11% or so I think.


So I guess at this point I'm wondering if this is even possible w/out additional hardware / signal boosting.

Is this a feasible distance for a wrt54gl? Or are those trees going to kill me...? Or do I just need to fine-tune my antenna alignment?

It's so close right now, but not quite there yet... I'm getting around 2-11% packet loss still, so not usable yet (but a whole lot better than the 50-70% I was getting... Smile )

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jjjacer
DD-WRT Novice


Joined: 04 Oct 2010
Posts: 1
Location: Jefferson, WI

PostPosted: Mon Oct 04, 2010 20:44    Post subject: Check Cable Reply with quote
The first thing i could think of is check what type of cable you are using to the antennas. Ive done about a half mile link with standard RG-58, a custom biquad, and a satellite dish. But i got alot of signal loss with the RG-58. usually its best to go with lmr400 as it has alot less signal loss. Check out the link below for a listing of different coax cables and what loss in db per meter of cabling.

http://en.wikipedia.org/wiki/Coaxial_cable

otherwise if you want to get an amplifier you can get the same one you listed a little cheaper from geeks.com

http://www.geeks.com/details.asp?invtid=ARG-2301A&cat=WLS

Also have you tried changing antenna diversity so that the router uses the grid antenna as the primary one?

Also you might be able to get a wireless spectrum analyzer to find the sweet spot on the channels.

this is the one i use, its cheap but useful.
http://www.cyberguys.com/product-details/?productid=37599&core_cross=SEARCH#page=page-1

Other than that make sure that all the connections are corrosion free due to weather. and to make sure they stay that way you can use a silicon spray on all the connections.

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JofCore
DD-WRT Novice


Joined: 24 Apr 2007
Posts: 38
Location: Farmland, MI

PostPosted: Wed Oct 06, 2010 17:54    Post subject: Re: Check Cable Reply with quote
jjjacer wrote:
The first thing i could think of is check what type of cable you are using to the antennas. Ive done about a half mile link with standard RG-58, a custom biquad, and a satellite dish. But i got alot of signal loss with the RG-58. usually its best to go with lmr400 as it has alot less signal loss. Check out the link below for a listing of different coax cables and what loss in db per meter of cabling.
http://en.wikipedia.org/wiki/Coaxial_cable

I'm using a short 3' LMR195 pigtail (https://ssl.zoovy.com/pnt/c=2MImteQODMPnHCRB8q6N3Y4CQ/s=wlanparts.com/product/RPTNCNM24/RP-TNC-to-N-Male-Pigtail-LMR-195-2.html). Radio is mounted on the roof w/the antenna so no long cable necessary.


Quote:

otherwise if you want to get an amplifier you can get the same one you listed a little cheaper from geeks.com

http://www.geeks.com/details.asp?invtid=ARG-2301A&cat=WLS

Yah i found that amazon has it pretty cheap too...

Quote:
Also have you tried changing antenna diversity so that the router uses the grid antenna as the primary one?

Hmm, no I didn't try that. i'm not sure exactly how to tell dd-wrt to do that? The only setting I could find for the antennas was to set the right or left to be TX or RX..

Quote:
Also you might be able to get a wireless spectrum analyzer to find the sweet spot on the channels.

this is the one i use, its cheap but useful.
http://www.cyberguys.com/product-details/?productid=37599&core_cross=SEARCH#page=page-1

Other than that make sure that all the connections are corrosion free due to weather. and to make sure they stay that way you can use a silicon spray on all the connections.

Yeah it's corrosion free, just been hooked up so no weather to hurt it yet.

thanks for the tips, unfortunately this project has been put on hold temporarily. I wasn't able to get a good enough signal no matter how many times I tried to align the antennas. So I assumed that the power I'm using (250mW) just isn't enough to get through the trees in the way. If this was a clear shot w/out any trees I'm sure I would have no problem getting the link up.

I had to move / relocate the antenna on the tree end right now anyway, since a new roof is being put on there and if I left the antenna where it was (chimney) I probably wouldn't be able to get to it ever again. So I had to take it down for the time being...

When I do put it back up, I'm going to do a gable/eave mount on that end so I have better accessibility to the antenna and radio.

But at this point, I'm kinda thinking that I should just ditch dd-wrt, and go with a Ubiquiti Bullet2 HP on either end. Then it's "all-in-one" and I don't have to worry about mounting an indoor amplifier in my outdoor enclosure w/my wrt54gl... and figure out how to supply power to the amp too. The ubiquiti unit is slightly more expensive than just an amp, but I would also need to buy new pigtails for the amp since it uses SMA and the wrt54gl uses TNC. So add in the extra cost of cable, the extra hassle of re-wiring and fitting everything into my box, and I'm thinking that maybe the Ubiquiti is the way to go.

If I had know about those in the first place, I probably never would have tried to do this with dd-wrt and my wrt54gl's :)

And finally, things are postponed right now due to lack of funds. I need to save some money up to get more parts and then continue..

thanks for the suggestions though!

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