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New Member

Fixed wireless long range antenna interfering with a cordless phone?

So we have been having ongoing wireless connectivity issues with our wireless ISP for last few months where it drops connection at random times a day.

We had numerous techs come by to take a look and now they are replacing the antenna on the roof of the building. Today I happened to accompany one of the techs and go up to the roof to see this sucker. I noticed they have just put up 2 high-rise condo buildings between our office and the ISP's CO roof-top narrowing the line-of-site to a hairline. When I came downstairs, geek in me hit Google to check the type of  frequency used by the fixed wireless long range antennas and noticed its the same as all other wifi networks i.e. 2.4 and 5Ghz etc.

What are the odds that someone in those buildings has a high powered wireless device, a phone or a microwave oven, that interferes with the line of site between the two point to point links. I don't know....penny for a thought?

6 REPLIES
Hall of Fame Super Silver

Fixed wireless long range antenna interfering with a cordless ph

Ricky,

When you mentioned that 2 new high-rise condo buildings where just put up and you have a hairline of line-of-site.... well that might be you problem.  Depending on what equipment they have or are using, RF need to have adequate "line-of-site".  Shooting a signal between two buildings isn't the best idea.  If your wireless connectivity was fine prior to those buildings being put up, then you might have to look at a different technology.  What did the engineer say when you went on the roof and noticed that they signal was shooting between some buildings?  Yu need to look at the Fresnel Zone.

http://www.wirelessconnections.net/calcs/FresnelZone.asp

-Scott
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Hall of Fame Super Gold

Fixed wireless long range antenna interfering with a cordless ph

I noticed they have just put up 2 high-rise condo buildings between our office and the ISP's CO roof-top narrowing the line-of-site to a hairline.

Remember that wireless point-to-point antennas are aimed VISUALLY.  These ain't high-end antennas which needs to be aimed (or callibrated) using specifically designed LASERS.

So why didn't the engineer told you this fact?  Easy, do you have any idea the stink that would have happened if he did?  That means the ISP would have to PAY and think of some other means to get your signals across.  Maybe they need to put a repeater in one of the condos mentioned.  Do you have any idea the logistics involved?  Who's going to pay for the "rental" of the repeater on that roof?  Because you've signed your contract with the ISP, it sure ain't going to be you paying for the bill. 

New Member

Fixed wireless long range antenna interfering with a cordless ph

I mentioned it to the tech and he said that those signals are very high power and normal interference can't cause the deterioration although I hardly doubt that.

He did put up a new antenna which I heard him say something called a "red line antenna"? (correct me if I am wrong).

That does sound like a laser antenna and my signal hasn't dropped since.

I'll keep an eye on it for now.

Hall of Fame Super Gold

Fixed wireless long range antenna interfering with a cordless ph

I mentioned it to the tech and he said that those signals are very high power and normal interference can't cause the deterioration although I hardly doubt that.

It doesn't matter.  Even if the tech installs a 10 Kilowatt power amplifier to the antenna, if you have a building standing in the way the radio signal will hit the building and scatter.  He should know that.  I'm no radio techie but I know this why can't he???

He did put up a new antenna which I heard him say something called a "red line antenna"? (correct me if I am wrong).

That does sound like a laser antenna and my signal hasn't dropped since.

The laser is simply used to calibrate the antenna particularly if you are dealing with pin-point accuracy.  Once the antennas are calibrated the laser is taken off (because it is expensive).

Ordinarily with Wi-Fi, as Scott has mentioned, the building(s) could be standing in the way of the Fresnel Zone. 

Hall of Fame Super Gold

Re: Fixed wireless long range antenna interfering with a cordles

Ordinarily with Wi-Fi, as Scott has mentioned, the building(s) could be standing in the way of the Fresnel Zone.

Let me explain a wee bit further.  Think of a dark room and your standing in front of a wall with a torch/flashlight.  Stand close to the wall and turn on the flashlight to the wall.  Notice the beam of the light is the same width as the head of the flashlight.  Now take two steps back.   Notice the width of the beam of light gets wider or bigger.  That's what Fresnel Zone is almost like.  The further you stand the wider the beam.  Now if you stick, say two obstacles, between point A and point B can you see the beam of light at the far end?  Not too brightly isn't it?

Hall of Fame Super Silver

Re: Fixed wireless long range antenna interfering with a cordles

You are the customer, so I would get the information on what they are using. What technology is being used, etc. this way you know what you have and other can can help you with issues. High power means what????? They are blasting the signal to improve SNR? There is also something known as overpowering which can also damage the radio. Again.... I don't know what they installed... With RF, you need I make sure you clear your Fresnel Zone.

Sent from Cisco Technical Support iPhone App

-Scott
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