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In reality, the links are probably just under 100M to the next column. The longest one is 200M, wich cuts across a carpark and has been fine. That is why I am now thinking water has penetrated the column somehow!

CP

Hi Guys

Yes, I agree with Grant. There is something not quite right here. With a link that has both antennas correctly pointed on the main lobe [ and assuming that under clear sky conditions you are receiving appropriate signal levels, SNR's etc ], I have never heard of a short link like that being affected.

A thing to check if you can: try to look at the logs of the links under clear sky, non-rainy conditions. If you let us know the values seen [ along with any packet re-transmissions ] and the manufacturer's name and type, I am sure that some folks here will be able to tell you whether those values "sound right" for the link.

There is a possibility that the links are "on the edge". In other words, perhaps some of the antennas have been de-pointed due to wind etc. Digital systems are tolerant of errors up to a point, and then very rapdily degrade. Old analog systems would "gracefully" degrade.

I'll put a posting up later on antenna main lobes and sidelobes, but be aware:

If an antenna is not pointing correctly [ due to install problems, wind, etc ] you have some leeway within the 3db points. In other words, if you were pointing "straight-on" on the main lobe [ called bore-sight ] and wind made the antenna move a bit [ perhaps a fixture was a little loose ], you'd generally be OK. However, the "field of vision", for want of a better expression, drops off very sharply and rapidly beyond this.

It is even possible that a side-lobe is being accidently used. On a short link with plenty of power being used, it is still possible to pick up a reasonable signal.

Once we get the data [ clear-sky and rainy, if possible ], we should be able to carry on from there.

I'd also check all the connectors to make 1000% certain that no water is in there. The other problem is that sometimes you cannot even see the water in the co-ax connectors, as it is water vapor and creeps in between the center pin and the dielectric [ plastic ] as well as on the inner surfaces of the connectors.

Many times when you have water problems it takes a little while for the water to dry out.

Do you have the commissioning data for the site. In other words when the links were put up, did someone record signal levels, SNR's packet re-try's etc ?

You can call the local MET office and ask them for times when rain was falling in your area. Compare that to the logs jsut to make sure that The rain is not a "red herring" and something else is causing it.

Was there any lightning ? Sometimes transients can creep through and cause hardware glitches and resets [ even on systems that have been grounded and protected - weird stuff lightning ]

That way we could look at what we had then with what we have now.

We would be comparing a known good thing [ hopefully, assuming the install was done well ] with something not so good.

Can you give us more info on the links:

Waht types of antennas are being used ?

Are you using any bridges etc ?

Dave

I???¡é?¡é?????¡é???¡éd give the the MET Office a bell. You will run into one of two types of people [ as they are in the Government ]:

???¡é?¡é?????¡­?¡°I???¡é?¡é?????¡é???¡ém sorry sir, we???¡é?¡é?????¡é???¡ére really not in the business of giving out that sort of information???¡é?¡é???????|. I really need to go???¡é?¡é???????|.???¡é?¡é????????

???¡é?¡é?????¡­?¡° But, it???¡é?¡é?????¡é???¡és only the bloody weather and it???¡é?¡é?????¡é???¡és already been and gone???¡é?¡é???????| surely you can look that up on a computer for me???¡é?¡é???????|???¡é?¡é???????|.???¡é?¡é????????

???¡é?¡é?????¡­?¡°I???¡é?¡é?????¡é???¡ém sorry sir, it???¡é?¡é?????¡é???¡és MUCH more complicated than that. Goodbye???¡é?¡é????????

Click.

Or you might get lucky:

???¡é?¡é?????¡­?¡°Hmm weather in downtown Manchester for last Thursday at 3:00 p.m. Let me have a look???¡é?¡é???????|.. yes ???¡é?¡é???????|???¡é?¡é???????|.there was a twenty minute squall with winds from the south-east at twenty miles an hour and heavy rain and lightning???¡é?¡é????????

???¡é?¡é?????¡­?¡°Brilliant???¡é?¡é???????|thanks a lot???¡é?¡é????????

???¡é?¡é?????¡­?¡°My pleasure sir, after all it???¡é?¡é?????¡é???¡és your tax money that keeps me here???¡é?¡é????????


http://www.metoffice.gov.uk/weather/uk/nw/manchester_forecast_weather.html

http://www.metoffice.gov.uk/corporate/contact/contact.html

Dave

Hi Neil

Yes, my wife is from here. I am recovering from spinal injuries and my wife picked up the CWNA book by chance as something for me to read.
Three years ago I was told by some of the best spinal surgeons and doctors in the UK and US that I would never walk again, would be in a wheelchair in six months and paralyzed from the waist down in two years.

I was determined that would not happen to me. I knew nothing about the body, but bought books on anatomy and learned the Latin names of the more than six hundred muscles in the body so that doctor's would not be able to baffle me with talk of "degenerative disk disease" and posterior protrusion of the nucleus pulposus via the annulus fibrosis.

I determined that my spine had been twisted in three places and my right sacro-iliac joint had been dislocated.

I could not prove it however until I met with a bloke called Al Meilus, a robotics engineer from General Electric who had his own health problems in the past and agreed with my diagnosis. With his help I have spent the last two years doing physical therapy and going from being completely crippled to leading a normal life.

I still have some pain when I sit and I have to wait until that goes away before I can physically sit for exams. I'm improving every week and hope to take my exams in about a month.

I spend my spare time helping people from around the world who have back problems get back on their feet.

Despite all the rubbish that is spoken about back pain by "experts" [ such as core strength and sit-ups - the WORST things you can do ], back pain boils down to some simple engineering principles.

When your head and shoulders move forward from where they are supposed to be, they create a force [ called a turning moment ]that tries to topple you over [ due to your center of gravity moving forward ]. Average human head weighs 8 pounds - the weight of a bowling ball. If nothing else happened, you would topple over. In order to prevent this, the brain sends a signal to the muscles of the lower back to tighten up to keep you erect [ the Greeks knew all about this a 1000 years ago and named the msucles "erector spinae" which means to keep the spine erect ]. When these muscles tighten up, they will eventually become painful. Also, they increase the curvature in the lower spine. That increases the pressure on the disks which can lead to herniations. The disks comprise two parts. A jelly center and a fibrous outer core. When there is too much pressure, the disk looses water and becomes smaller leading to degenerative disk disease.

The solution: Get your posture back by getting your head and shoulders back. Also, when we sit, muscles in the pelvis tighten up and tilt the pelvis forward, tipping the upper body. Brain sends the same signal to the back muscles to tighten up to keep you upright. The solution ???¡é?¡é?????¡é?€?? loosen up the FRONT of the body, not the back [ which is doing what it is supposed to do ]. I have not seen a single case where this has not worked. Where do we get forward head and shoulders from ? One example- have a look around the office at the posture of people using laptops - not very good...much, much slouching.

Dave