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HX 50 and Telstar11N in Côte d'Ivoire

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YV
Ex Member


Jun 6th, 2011 at 3:58pm  
Hello,

We have acquired from Bentley Walker a VSAT solution, including a HX50 modem and a 1.2m dish.
BW said it would be easy to connect by ourselves from Abidjan to Telstar 11 N satellite and recommended us a satellite meter Horizon HDSM USB to assist us. We have installed the dish respecting the instructions and the angle values.
However, since then, the result has proved disappointing. Using the satellite meter with BW configuration for T11N, signal kept showing 56db. We have done some searches and we were able to download another configuration file on Horizon Web site. Thanks to this file we are now able to get a 72db. However the meter never locks on T11N.

BW Technical help support is now advising us to contact a local installer…
Before going to this next level, we tent to explain our issues, as someone would be able to give us some clues.
Can we rely in satellite meter results?
Is it possible to connect to Telstar 11 N from Abidjan with a 1.2m dish and KU band?

Our latitude 5.36365, longitude: -3.98628
Azimuth 270, elevation 51, polarization 80
RX polarization horizontal, TX vertical

Thank for your help,
YV
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Eric Johnston
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Reply #1 - Jun 6th, 2011 at 5:53pm  
The meter will indicate when you are pointed at any satellite, and any polarisation angle, and help you peak up.

You have found a satellite. Note the angles carefully on your dish mount. In you have an elevation scale write down the measured elevation scale reading. Measure the lengths of azimuth and elevation adjustment screws and write these down together with drawings of how the measurements were made.  You now have a record of your first found satellite.  If you get lost you can now always get back to the starting satellite.

In your view towards the west, the satellites are in a line almost vertically up/down in the sky.  Having found one satellite, the next satellites either way along the orbit will be easily found by simply going up or down.  This will be necessary if your initially found satellite is the wrong one.

It is usual to find your satellite by setting the elevation angle accurately by measurement and then swinging the dish boldly sideways.  You will find a satellite.  Yours will be that one or one or two next satellites, above or below.  Q1 What is you measured elevation angle ?  Q2 What is your dish model number ?  Q3 Does the bracket arrangement behind comprise a large grey coloured wedge shaped box ? Like this perhaps:
...

Having peaked up on the satellite try to see if it is the correct satellite. The correct satellite is confirmed when the HX50 modem RX LED comes on and gives a signal reading like 90.  If you are on the wrong satellite or wrong polarisation or your configuration settings (frequency, symbol rate, LNB type) are wrong then the HX50 signal reading will only go up to a maximum of 29.

If the Horizon meter has been programmed to look for a TV carrier that is present on the polarisation you want and in the frequency band possible using your LNB then the meter will say "Telstar 11N found".  If it does not say this the meter will still enable you to peak up on the satellite.

Try the two alternative polarisations.  These are with the LNB/BUC assembly tilted 80 deg clockwise (as viewed facing forwards towards the satellite in the sky), starting from upwards or sideways.  Q4  Please say what is your LNB model number ?  It will then  be possible to tell you specifically how to set your polarisation to horizontal or vertical.

Telstar 11N provides really excellent powerful coverage of Côte d'Ivoire, and all other countries along that coast.
ref: http://www.loralskynet.com/pdf/T11N_footprint.pdf

Best regards, Eric.
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« Last Edit: Jun 6th, 2011 at 7:19pm by Admin1 »  
 
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YV
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Reply #2 - Jun 7th, 2011 at 9:33am  
Thank you Eric for your precise reply.
We have swung the dish all around, but there is only one position where the satellite meter reacted (72db)
Folowing answers to your questions:
Q1:  elevation 51
Q2: see pictures sent to eric@satsig.net
Q3: yes
Q4: 1501882-0002

Greetings,
YV
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Eric Johnston
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Reply #3 - Jun 7th, 2011 at 11:53am  
Elevation:
...

It is not easy to measure the elevation in the photo. 90 minus the slope of the back plate of the grey wedge shaped plastic box is what matters.

It appears to me that your beam elevation angle might be more like 59 deg than your wanted 51 deg. Not sure. You may well have it correct.

You will not find any other satellites by moving the dish sideways. The other satellites are in near vertical line up and down the sky.

Try measuring your elevation accurately - see example in earlier posting above.  If necessary, print out an inclinometer.  http://www.satsig.net/pointing/how-to-make-inclinometer.htm

I am working on a reply regarding setting the initial polarisation name and then applying the 80 deg adjustment amount.

You have the azimuth about right - towards west - where the sun sets.
...  ...

Best regards, Eric.
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« Last Edit: Jun 7th, 2011 at 2:24pm by Admin1 »  
 
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Eric Johnston
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Reply #4 - Jun 7th, 2011 at 12:23pm  
Polarisation

You have been told to receive Horizontal polarisation name.

You need to set this initial start position by having the Universal LNB F connector pointed out sideways.

You then need to apply an 80 deg clockwise adjustment amount, as viewed from standing behind the dish and facing forwards towards the satellite in the sky.

You can achieve the result in two ways.

1. (Eric's method) You are presently very near (2 deg error) to Horizontal name polarisation starting position. ...
Turn the feed system in its yokes 2 deg till the tick mark is in the middle. You are now at the exact Horizontal receive polarisation name start position.  Go behind the dish and loosen the 4 polarisation bolts and turn the entire dish 80 deg clockwise and retighten the 4 bolts. While turning the dish using the polarisation plate, the beam should stay pointed at the satellite but you will need to peak up again slighty. Note that you need to apply an amount of 80 deg clockwise.  The actual polarisation scale numbers may read backwards. Ignore the numbers and concentrate on counting the amount of 80 deg. The feed support arm will be on the left side, just below exactly sideways, as viewed from behind the dish.  During commissioning Bentley Walker may ask you to make small adjustments to the polarisation to minimise your cross-pol interference.  You may turn the feed system in its yoke by +/- 5 deg.  Note the 505 scale on the horn throat. The 505 must be directly away from the feed support arm.

2. (Bentley Walker method).  Note your feed polarisation setting is presently 2 deg clockwise.  Loosen the feed support yokes and turn the feed system clockwise by an amount of 78 deg in the same direction, so the final reading is 80 deg. If your system fails to pass its cross-pol testing I would suggest that you undo the 12 hole flange at the grey/white joint where is the single/double tick mark and reattach the feed horn/adaptor tube to the white OMT/LNB so that the 505 is as near as possible directly away from the feed support arm.

Best regards, Eric.
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« Last Edit: Jun 7th, 2011 at 2:30pm by Admin1 »  
 
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Eric Johnston
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Reply #5 - Jun 7th, 2011 at 12:31pm  
Locking to the wanted carrier.

While you are on the wrong polarisation or wrong satellite you will get readings on the HX modem up to a maximum of 29.  29 is a very powerful signal.

Once all is correct the modem RX LED will come on and the signal measurement will go up to a number like 90.

The configuration of the HX modem is critical.  Set the downlink carrier frequency, symbol rate and LNB type as told (plus all the other parameters).  You may have been given a cfg file which will make "Universal LNB" or "1501882-0002" appear in the pull down menu.

The meter works similarly, if it manages to receive a pre-programmed TV carrier it will show "Telstar 11N satellite found"

Once you have locked to the wanted carrier, spend at least 30 minutes peaking up, first in azimuth, then elevation.  In azimuth loosen the two nuts a small amount so you can gently pull the dish sideways to rest against each nut alternately, either way from the satellite. Adjust one nut till the degraded quality either way is exactly the same, e.g. 70 and 70.  Then move physically to the centre and tighten the nuts equally.

Peak up the elevation by marking one flat with felt tip pen. Count turns and flats across the beam peak and wind  back to the beam center.

Best regards, Eric.
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« Last Edit: Jun 7th, 2011 at 3:29pm by Admin1 »  
 
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YV
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Reply #6 - Jun 7th, 2011 at 5:27pm  
Congratulation Eric. Thanks to your explanations, we now have locked our modem on to the satellite, with a 92db. We had to correct our elevation and polarisation settings.
We have been got off onto a wrong track since Horizon satellite meter was showing results for another satellite.  Even now this meter still can not find a good signal. Anyway, using directely the HX modem to read the signal measurement was a good solution.
Thank you very much for your kind support.
YV
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A.Walker
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Reply #7 - Jun 8th, 2011 at 9:30pm  
Are you up and running ?

Anthony@Bentleywalker.com
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