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pointing to IS 907

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Apr 3rd, 2007 at 12:14pm  
hello all
i have 2 year experience ponting VSAT but i have a problem today pointing to IS907 near the us abassy here in gabon because i do the same job in another place with same equipment ,same site survey condition it work very well so i want to know if it is possible for the guy of us ambassy to muddled satellite signal
best regards
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Eric Johnston
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Reply #1 - Apr 3rd, 2007 at 12:40pm  
If you are receiving in the 4 GHz band, there is the possibility of interference from terrestrial sources such as microwave links and other services that are authorised to operate in the same frequency bands.

To diagnose the problem you need a spectrum analyser, point the dish at zero elevation angle and swing all around through 360 deg.  That will help identify terrestrial sources such as radio relay link masts, radar etc.

To reduce interference block the path.  Put your dish low down behind walls, earth banks etc so the dish can't see the interfering source.  The greater the angle across the top edge of the obstruction the better.  A rounded, radio absorbant edge is better then a metal knife edge.

Read here:

http://www.satsig.net/satellite/reducing-interference-satellite-tv.htm

http://www.satsig.net/itu/c-band-spectrum.htm
wxw
Best regards, Eric.

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Reply #2 - Apr 3rd, 2007 at 1:04pm  
Another thing to consider might be a second (reflected) signal. I was involved with an installation for the embassy in Manila, which experienced mysterious interference of a cyclic nature. Happened couple times a day, but never at exactly the same time. Finally tracked down interference to a billboard across the street from the embassy. The waters of Manila Bay provided the first bounce. When the rising or falling tide was at just the right level, the signal reflected off the water and hit the billboard. Since the second signal moved with the tide, it eventually hit a certain angle where the bounce off the billboard hit the embassy parabola.

The second signal was a mirror image, but its delayed arrival induced signal phase issues. Jitter. Troubleshooting the hardware itself was getting nowhere, so I resorted to a SWAG  - and asked the embassy people how hard it would be to get the billboard removed. Billboard eventually came down, problem went away.

//greg//
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Reply #3 - Apr 3rd, 2007 at 2:13pm  
hello eric and greg
i receiving in  ku band and with my spectrum analizer a satlook digital nit i point the dish at zero elevation angle and swing all around through 180 deg west side but no signal i do all the possible test .is et possible that something like a radar interfere with my signal ?
best regards
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Reply #4 - Apr 3rd, 2007 at 2:21pm  
Yes, it's possible. Ku-band is also used in traffic control (to change signal lights) and in police radar. Even a vehicle equipped with an energized Ku-band radar detector can cause local oscillator interference.

Another thing to check for is voltage on ground. You could have a contaminated power source.

//greg//
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Reply #5 - Oct 7th, 2007 at 2:46pm  
Dear Sirs,



I am from Taiwan. I search the information about "reduce Radar Detector satellite ku signal interference "



I live at 8th floor and the building is 14 floors high. I put my satellite dish on my veranda. However, I got bad signal when the car what use the radar detector is coming.



Has any way can I do to avoid the radar detector interference ?

sorry for my poor English and thanks for you watching this.

Bruce
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Eric Johnston
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Reply #6 - Oct 8th, 2007 at 9:51am  
If possible, move the dish backwards and downwards on your veranda so it is no longer visible from the road.   This is called site shielding.

The beam from your dish must still be able to see the satellite of course, so check carefully that the beam passes over the top of the balcony and below the roof above.

Best regards, Eric.
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Reply #7 - Oct 8th, 2007 at 5:37pm  
Dear Eric,

Thanks so much for you repling my message. Especially for my bad english.

Can I post image here? I face this problem for 13 months long. I do have some experience. If I could post the image then it could be easier to let you guys know what I am talking about.

Thanks again !
wish you have a best life.

Bruce
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Eric Johnston
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Reply #8 - Oct 8th, 2007 at 5:46pm  
Send the image to me by email:  eric@satsig.net

I will add it to this forum posting.  No problem.

Best regards, Eric.
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Reply #9 - Oct 8th, 2007 at 6:05pm  
Dear Eric,

I am so touching for your help. As I said, I am from Taiwan. If you can read Chinese. We do chat the Satellite as here. There is very friendly like what you did for me.

I will prepare some data to let you or any other sir to know it.
Thanks a lot !

http://www.myav.com.tw/forum/forumdisplay.php?s=&forumid=50

Welcome anyone be there.

Bruce

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