intermitenet Interference

[dahhbuzz]

I have two 5.8 Ghz antennas(a)Redline 2ft 28dB and an Airspan wipll 15db antenna) about 1.5 m apart on a mast. They seem to coexist pretty well till yesterday when they started to interfere with each other. Does anybody have an expalnation for this?(NO settings were changed on either radio) Could this be caused by the change in the atmoshpere density resulting in more refraction?


Bosun

 

[lui3]

are they on different channels?

what is the beamwidth of each antenna and are they both directional antenna.


are you sure they are interfere with each other or is it corrosion setting in on one of the connectors. rust does bad things to antenna connectors when not properly sealed.



Lui3
CCNP,CCDA,A+/Net+
Cisco Wireless Specialization

 

[dahhbuzz]

the parabolic has a beam width of 4.5 degrees, the 15bD has a beamwidth of about 9-10 degrees.

They are both directional antennas.

ALL connctors are ok and water tight. (The airspan cable is CAT5)

The problem is that the interference develops ONLY towards afternoon.

They are on diff channels. The solution will be to move the antennas further away, change polarity or relocate.

I just wanted to know if anyone had an explanation for this pheonomenon.

Thx

 

[G0AOZ]

You seem convinced that signals from one antenna are interfering with reception on the other. Have you been able to specifically prove this? Do you see this interference on a spectrum analyser, or just how is it showing up?

How old are the antenna installations, and have all the connectors, securing bolts etc., been carefully checked? As LUI3 suggests, the "rusty bolt" effect can play a part in causing problems here, together with any ingress of moisture etc.

You have some nice gainy antennas there. They will be capable of receiving signals from some distance away. Could the source of the interference be several hundreds of feet away from your antenna installation?

Over what distance are you operating with this setup?

ROGER.

 

[dahhbuzz]

Hi GOAOZ
Firstly when I put on the Airspan(radio 1) all seems to work well for a while then toward afternoon my Redline radio (radio 2) ceases to funtion. If I turn off the Airspan the Redline functions well once again.

I also have a tool for monitoring the SINADR of the Redline and with the Airspan on you can see the SINADR trace going in a zig zag line. Once the Airspan is switched off the trace becomes a straight line.

The Airspan Link is about 12 Km

 

[lui3]

Hey dahhbuzz,

I am not familiar with the term SINADR, can you explain it for me and its relevance to your problem? Much thanks.




Lui3
CCNP,CCDA,A+/Net+
Cisco Wireless Specialization

 

[dahhbuzz]

SINADR Is Basically the signal to noise ratio. With the Airspan radio on the signal to noise ratio just seems to go beserk. Even with the antenna mounted 3m away.

Bosun

 

[lui3]

Is it possible to switch channels on the radios. Ie put the interferring channel on the other radio and vice versa. That way you could figure out if the symptom moved to the other antenna you could find the interference on the channel itself. Also are these antennas supporting the same line or are they supporting seperate links. I am just thinking maybe it could be a fresnel zone issue with one of them and some rogue channel interference on the link. just a thought.

Lui3
CCNP,CCDA,A+/Net+
Cisco Wireless Specialization

 

[G0AOZ]

From what you describe, it suggests there's a possible problem with the Airline radio. Maybe a gradual heating up of some components within it are causing it to produce an ever widening transmitted signal bandwith. Is that radio getting very hot perhaps?

I use an aerosol containing a refrigerant which can be sprayed onto or around components which I think are heat intolerant - this can easily identify problems similar to that which you're experiencing...

Conversely, could it be that your Redline radio receiver front end is "opening up" to other channels due to heating?


ROGER.