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VSAT technology and installation >> HughesNet and Hughes HX VSATs >> Pointing Dish: need help in Afghanistan

Message started by Montourage on Oct 17th, 2010 at 8:20pm

Title: Pointing Dish: need help in Afghanistan
Post by Montourage on Oct 17th, 2010 at 8:20pm
Hi there,

I've been working a week on setting trying to link with the satillite with no luck.   Trying to trouble shoot it with support has not helped much.  All the settings have been checked and rechecked to no avail.  I think one of the issues is that on the roof top where the dish is located we have strong magnetic interference.

I go from one point on top to another and the azimuth moves as much as 30-45 degrees.  I took a reading from off the building and it seems to be in a direction I've pointed that dish in before with no luck.

Wondering if anyone has any ideas from the photos.

Title: Re: Pointing Dish need help in Afghanistan
Post by Eric Johnston on Oct 17th, 2010 at 9:16pm
Feed/LNB/BUC assembly:

This is correct. The 505 on the feed throat should be directly away from the feed support arm.  The fat lump on the feed throat should be towards the feed arm, presumably hidden in the yoke. The double tick mark on the 12 hole flange is to the side (visible in the image).
When the antenna is rotated so the feed arm is at the bottom the receive polarisation is horiziontal and the transmit polarisation vertical.  The LNB shown is the Hughes universal LNB type, which needs the 22kHz tone selected or not according the satellite frequency.

Elevation angle:

If you set the elevation correct, and the pole is vertical, you should be able to swing the beam over a very wide azimuth angle and still find the satellite. But, it is essential to have the pole upright so the elevation angle stays the same as you swing the dish sideways.  It may be an optical illusion but it appears the pole is tilted forwards.
If the 4 screws are rather slack the dish will sag forwards a bit, so add one or two degrees to the setting.

Azimuth setting:

The blue line in the picture above, relative to the building line, should be useful guide, if your magnetic compass is not giving a useful reading.  Azimuth accuracy is not usually important as you can swing the dish 90 deg sideways either way and still find the satellite reliably if you have the elevation angle correct. The satellite is in an approx south west direction, say half way between where the sun is at mid day and where the sun sets. If you go to this page and set the map centre to your exact dish position the blue line may help you align the dish relative to the roof corner, next building wall etc.

You need to apply an adjustment amount of +39 deg clockwise rotation, as viewed while standing behind the dish and facing forwards towards the saatellite in the sky.

When your feed arm is at the bottom the receive polarisation is Horizontal starting position.

When your feed arm is at the side (either side will do)the receive polarisation is Vertical starting position.

Your configuration says you want Vertical receive polarisation.  

Your picture looks about right.

Procedure: Turn the dish so the feed arm is exactly on the right hand side (as viewed from the rear and facing towards the aatellite in the sky). This is your Vertical receive polarisation starting position.

Now apply the +39 deg clockwise adjustment which will involve the feed arm coming down towards the bottom by an amount of 39 deg. I'm not sure what the scale reading will be, probably 90 - 39 = 51 (+ or - I am not sure.)

You have been told Vertical receive. If this information is wrong try turning the dish 90 deg from the position set above.

Provided the 4 polarisation bolts are not excessively loose, the beam remains more or less aimed at the satellite all the time while you rotate the antenna polarisation scale. It will be probably be necessary to slightly peak up after each polarisation adjustment.

Config file:
Recent HX installs, particularly those with the Hughes universal LNB have been provided with a config file which has affected the 22kHz tone ON/OFF state.

Check with your service provider regarding the receive polarisation, any requirement to load a cfg file and and the 22kHz tone status.

There is nothing to stop you trying 22kHz tone ON/OFF and polarisation options.

Note that if you get a signal reading that peaks up to 30 you have found a very strong satellite signal.  Mark that point. It could be your wanted satellite but wrong polarisation or config or it could be wrong satellite. The next satellites are in a diagonal line either way, up towards south, down towards west. The signal reading will only go above 30 once all is correct and will peak up around 90.

Best regards, Eric.

Title: Re: Pointing Dish need help in Afghanistan
Post by Montourage on Oct 18th, 2010 at 6:18pm
Thanks Eric for the fast and detailed reply.  I appreciate your time and effort in helping us.  It has been very frustrating.

Today my partner whom was in charge of the setup secured it more properly.  I had noticed what you had and dismissed it too soon in my head at first and didn't revisit that thought tell you mentioned it.  I just went up there and it is far more level.

We used a better inclometer this time.  I'm going to change some settings in the router as you mentioned.  We hit 29 a lot but never above.  I hope perhps the polorization is just wrong so we'll see if we can get it to peak higher.  

I took some more photos as well and will be posting them soon.

Thanks again.

Title: Re: Pointing Dish need help in Afghanistan
Post by Eric Johnston on Oct 18th, 2010 at 6:51pm
The signal scale reading works in two sections.  0-29 is noise power measurement and responds to any and all satellites. 30-100 only comes into action once your demod locks onto the wanted carrier, which means you have the correct satellite and (approx) correct polarisation and correct config (particularly symbol rate, tuning and 22kHz tone).

29 is a maximum value.

If you have hit 29 and the elevation angle (inclinometer) is about right then you are on the wanted satellite or the next one either way. Note that the dish may be sagging down 1 or 2 deg.

Whilst on the satellite (with 29) try 22kHz tone on/off and try the other polarisation (turn dish 90 deg and repeak the 29.) and again test 22kHz tone on/off.

***  Don't alter the 9000000 symbol rate or the 19582 tuning, I have checked these are correct for the HX carrier on the 36E satellite.

If no good, try up left and down right and look at the adjacent satellites and repeat the tests.

Best regards, Eric.

*** New values April 2011: symbol rate 1000000, tuning 19588

Title: Re: Pointing Dish: need help in Afghanistan
Post by Dan-BW on Oct 19th, 2010 at 3:51pm
Dear Sir,

I am sorry to hear that you have been experiencing difficulties with your installation.

Would you please be so kind as to try adjusting your polarisation tilt to approximately +50.9 degrees (Our W7 service utilises a vertical RX polarisation).

Daniel Kennard
Bentley Walker Technical Support

Title: Re: Pointing Dish: need help in Afghanistan
Post by Eric Johnston on Nov 4th, 2010 at 5:26pm
I have had an email from the site saying that all is now working well. The signal level is about 91%.

A Sat Meter was used to find the satellite and peak up.

Quote "The blue azimuth line the map was dead on as our building is lined up with the road and the Dish is pointed slightly to the left."

Quote "I consistently get 1 MBps on the download side of things on the highest package and that seems right inline with what they say we will get."

Best regards, Eric.

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