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Satellite internet Please help

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Posts: 1
Jan 12th, 2009 at 10:31am  
Hi everyone,

This is my first post and I hope I'll be able to get help from you guys. Here is the situation

I m working on a satellite connection to get this to work our ISP located in an another country, Usually they provide us configured devices, & what we have to do is just connect  those devices & align the dish & it should be good to go. But What happened is the settings which were activated on our devices they been transfered to one of our another site & we were given new settings which I implemented. I don't know alot about this stuff but rightnow as they can't send someone here So All I did is just changed the IP's in router dvb & modem settings as requested. Before our ISP people they said the transmission is weak so we need to replace the modem. Then after changing the modem still there is no internet.  One day after changing the modem they told me they are able to get to the router But second day said they can't get to the router & blaming us that we did something on our side. But we didn't change anything. Let me tell you that the signal on my dvb is locked. I can ping my router from a work station & I can ping my dvb too.

I've a few questions

1. I changed just the eth & serial IP in the router do I need to change the other settings in the router ?
2. I removed the front side of feed horn and LNB But I don't remember how it was connected before does this matter if it has been rotated & the upper side has changed.??

Our ISP people they can see the carrier They were able to get to the router but now they are not even can get to the router.

We are using advantech modem a cisco router 2600 serias & a comtech dvb. Our buc is connected to Modem & a serial cable from modem to router & the lnb cable goes to dvb. If you need more information please tell me as I don't know what I have to tell your guys.

Could you please help me figure out this problem.

Thanks in advance
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Eric Johnston
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Posts: 2109
Reply #1 - Jan 12th, 2009 at 11:36am  
2. I removed the front side of feed horn and LNB But I don't remember how it was connected before does this matter if it has been rotated & the upper side has changed.??

Yes, it does matter a great deal.

Two points:

1.  When you rejoin the waveguides it is essential that the rectangular holes line up.

2.  The entire feed assembly/BUC and LNB can all be rotated in its yoke(s).  The rotation angle is the polarisation and must be set to 1 deg accuracy.  This is difficult.

If you have changed the rotation angle you will now need to reset it correctly.  

Carefully loosen the yokes so you can gently rotate the feed assembly. Avoid getting your arm/body in the beam, so do this from the side or underneath and reach up.  

Watch the receive lock indicator on the DVB receiver.  Rotate the entire feed assembly slowly through 360 deg.  There will be two regions where the lock is good and two regions where the lock fails.  Mark the four exact angles where the lock transitions on/off with pencil.  Then set to the optimum middle position by halving between the marked transition points.

Alternatively, it is possible to set polarisation tilt angle  by calculation.   In this case you need to initially set the polarisation to nominal as told to you by the hub.  Horizontal polarisation would require the LNB arm to be directly upwards (or downwards).  Vertical polarisation would require the LNB side arm to be sideways (either side will do).  Now apply the calculated adjustment angle.  While facing towards the satellite, clockwise is positive.  Get your angle here:  Dish pointing Iraq or Dish pointing Afghanistan

With the polarisation correct, you might then make small adjustments in azimuth and elevation to peak up, while taking accurate receive quality measurements (on the DVB receiver).  Small adjustments means like 1/6th turn of the nut at a time. Record each adjustment and measurement till at the absolute maximum (i.e. half way between two equally degraded measurements either side).  Perfection matters as the transmit beam is narrower then the receive beam.  A 'weak' transmit signal can occur with very slight mispointing.

Get your ISP to help with the IP settings.  Work methodically and get everything correct.

Best regards, Eric.
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Posts: 9
Reply #2 - Jan 13th, 2009 at 4:16pm  
You didn't mention your location or contact point, but if you weren't able to solve the problem we might be able to guide you remotely and instruct you to reconfigure.
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