we have a remote node running v 1.0.0 software on a wrt54gs router with a relysis amp (1 watt) and ~ 16 dBi sector antenna.  this node can be seen from as far away as 15 miles with a decent LQ (~90%) but all we can see is the IP address. this is from other nodes running the same version software. we were able to connect from ~100ft but nothing beyond that. the same is true for other nodes as seen by the remote node.!

any idea what is going on?

thanks.. N7RTA

Remove the amp and test it again.  Amplifiers generally add more in the way of spurious noise than actual distance benefit to these systems.  You don't mention how the remote nodes are configured (antenna gain for instance).  It is likely that the remote node is hearing the local node but not vice-versa.  It could also be that one side is in a higher noise environment.  You might try shifting both sites to horizontal polarization (you can get up to 20dB in unwanted signal rejection with this technique).  I have bench-marked the Linksys routers at several miles with 18dBi antennas at each end (15 miles may be stretch though... perhaps consider a Ubiquiti Bullet M2 or a Rocket M2 if you're already using a Ubiquiti sector antenna).

Andre, K6AH

Thank you both for your replies!

our remote site node is co-located with a 2 meter and 70 cm repeater.  but,  there are lots of commercial transmitters close by.  the router shows a noise floor of ~-70 dBm.

the antenna used on the remote site is a commercially built sector array (HBW=90 degrees, VBW=7.5 degrees, gain ~16 dBi)

we are wondering also if multi-path is a factor. on the node opposite the remote site (located in a park), when lots of people show up, the signal levels really start to vary.

i have read several articles where circular polarization was used to mitigate multi-path. has anyone experimented with circular polarization?

thanks for your help!

N7RTA

That's a high noise level.  I would definitely try horizontal polarization.  On the multipath question, you need to be sure the Freznel Zone is clear (see http://en.wikipedia.org/wiki/Fresnel_zone).  You can estimate the required clearance using the formula: 36*sqrt(miles/GHz)=clearance in feet.  Using 15 miles and 2.4GHz, that results in a clearance requirement of about 90' above and below the beam at the midpoint between the two nodes:

36*sqrt(15/2.4)=

36*sqrt(6.25)=

36*2.5=90’

So check to be sure that area isn't obstructed in any way.  However, again I'll suggest Ubiquiti gear in a scenario such as this.  You will gain nearly 10dB in receiver sensitivity (which will help when you get the noise issue resolved) and nearly 10dB in higher power output.  I don't have any experience in circular polarization.

Andre, K6AH

I have seen this before.  What I came up with was both sides need to be hearing each other to get the handshaking that goes on within OLSR.  The far end node is not seeing you that well.

I had two Linksys boxes, separated by 8 miles.  Box 1 was a 24 db grid antenna, Box 2 was a 13 db Horizontal Polarized omni.  I could see the omni but it was not seeing me all that well.  I would just get the ip address to show up.  My experience is the receive side of a Linksys is not all that good.

I fixed this problem by changing out the Linksys attached to the omni with a Bullet M2HP, and then swapped the grid antenna/linksys for a Rocket M2 and a Sector antenna similar to yours.  Problem Solved.

We have another location with the other problem similar to yours.  We counted 31 ssid's on channel 1.  Our intention is to try and solve this by switching to 5.8 GHz.  Beam antennas may also help to eliminate some of the other strong signals.  If 3.4 GHz was available I would suggest that instead.

Our experience with amps is don't bother.  Signal path is the main problem.  If you have a good path you won't need the amp.

Clint, AE5CA