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KaSat install problem at beam edge

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sab2012
Ex Member


Jul 23rd, 2012 at 1:56pm  
I have bought KaSat system 2 months ago and I tried many times to setup the system but I get low signal (( 7 dB)) snr which is very low. before I buy it I asked the company about the coverage they told me it is OK with your place but it is not I am using 120 cm  dish and my location is  (( MIZDAH, LIBYA  ))

latitude of 31.44782220
longitude of 12.98385640

Please any one can help me in this.
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« Last Edit: Jul 23rd, 2012 at 4:25pm by Admin1 »  
 
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Admin1
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Reply #1 - Jul 23rd, 2012 at 3:46pm  
`I've marked where your location is on the map below:
...
It is hard to spot your location in the small scale map.
The accuracy of the map is somewhat uncertain and as the satellite is not fixed in space the beams wobble about a bit.  I would expect you to see different receive measurements during the day for such a beam edge site location. The beam edge is quite steep and even small satellite pointing error causes significant changes in level.

There are four (*) N.Africa beams which seem somewhat larger than the standard beam (like the Algeria beam). I suspect that the red contours refer to further out contours of the beam and that the larger size is a result of assuming that a downlink carrier for sites like yours is set up with a bit rate, modulation and coding to suit 1.2m dish sizes at well beyond the blue contour. The blue line is the limit for the "standard" package and you are well outside this blue line.  Something special may be necessary for you.  Has your service reseller contacted Skylogic to get something special set up for you ?

You seem to be just on or outside the red line for 120cm dish + 4 watt (Shaped service and different pricing).

For Ka band (20/30 GHz) the surface accuracy and solid metallic surface quality of your 1.2m dish will be very important. 1mm (1/10th wavelength) is the maximum distortion allowed and is difficult to achieve with a 1.2m dish.
I don't know what your dish looks like.  If it is a standard Ku band dish it may not be suitable.
A problem with many dishes is that the weight of the feed/radio assembly pulls down on the two side struts attached to the dish and distorts the dish shape. You can check for dish distortion by putting tight sewing thread or fishing lines up/down and across the front face. They should just touch in the middle. Ref: http://www.satsig.net/pointing/rear-side-struts.htm   Less than 1mm gap is needed.

Very slight damage to the dish, stress due to uneven tightening of 4 bolts attaching it to the rear hub, or pulling on the sides due to side struts will ruin the gain.

The dish shape must be treated with great delicacy !

I am presuming the focus (distance from feed to lower edge of the dish) is correct.  If the focal distance is adjustable and therefore could be wrong, read the dish assembly instructions carefully.

If the dish shape is perfect and you still don't get a good enough signal then I guess that you are simply too far from the beam centre.

(*) The "Benghazi" beam does not appear to be available for Tooway service. Sold to the military or to TV company or repointed to Iraq have all been suggested.

Best regards, Eric.
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« Last Edit: Jul 23rd, 2012 at 9:46pm by Admin1 »  
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dirkovision
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Reply #2 - Sep 26th, 2012 at 10:12am  
Quote:
I have bought KaSat system 2 months ago and I tried many times to setup the system but I get low signal (( 7 dB)) snr which is very low. before I buy it I asked the company about the coverage they told me it is OK with your place but it is not I am using 120 cm  dish and my location is  (( MIZDAH, LIBYA  ))

latitude of 31.44782220
longitude of 12.98385640

Please any one can help me in this.



How we solve in Iraq (beam 83) is to move some miles away from the beam-edge, commission, (db must be above 9.0 ) connect, browse and then go back to site where the link is needed. works perfect. No loss in speed, even not if dB eb/no drops below 6.0...
Screenies available.
-+
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sab2012
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Reply #3 - Sep 26th, 2012 at 12:07pm  
thank you dirkovision

but i did not get the point do you mean to connect the system in nearest place that have good cover browse then get back to my location and connect it  and work probably as you said please tell me  ASAP  in details
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Reply #4 - Sep 26th, 2012 at 1:07pm  
I suggest you put the dish, cable and modem in a car and drive NW towards the beam centre (towards Tunisia, see map above).  Go to a friends house and temporarily power up the equipment, point the dish (you must get 9 dB or more) and commission it with the hub.
Try browsing web sites etc and check it all works OK.

Then put it all back in the car and drive home.

At home, set it all up again, point really carefully and there is a chance it will work if the signal is between 6 and 7 dB.

Your service may fail in slight rain.
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dirkovision
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Reply #5 - Sep 27th, 2012 at 11:39am  
maybe. but in the region we do these tricks are severe sandstorms. So far no problem. knock wood.
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« Last Edit: Sep 27th, 2012 at 1:47pm by Admin1 »  
 
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dirkovision
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Reply #6 - Nov 6th, 2012 at 3:25pm  
[quote author=dirkovision link=1343048217/0#5 date=1348742391]maybe. but in the region we do these tricks are severe sandstorms. So far no problem. knock wood.[/quote]

after 3 months uptime: still no cut-off, but by Skylogic because of bad weather conditions in Italy.
System comes back and gets its lease without problem.

Looks it helps knocling wood..
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