SatSig topic:

I-Direct Installation: Guyana

(Read 19763 times)

Oct 18^th, 2009 at 3:43pm

Hello,

I need some help pointing an iDirect solution. The satellite i am pointing to is 30w. My co-ordinates are 3.39N, 58.41w.

Based upon my calculations we are supposed to point at Elevation=56, Az=96, Pol= - 82 deg.

We are getting some problems where we getting a green light on the Rx port at the back of the IDU, but we are not receiving any indication on the signal meter that is part of the software of the IDU.

Can someone offer some help.?

Keeron

Oct 18^th, 2009 at 5:22pm

You've posted the AZ angle relative to true north. If you're using a compass, you should be using the AZ angle corrected for magnetic deviation (~111 degrees). And relative to EL, your dish mount may have an engineered offset angle - information that should be included in either the installation manual or the tech specs. If yes, it must be factored into the calculated EL number to arrive at the working EL angle. See https://www.satsig.net/22-deg-offset-dish.htm

//greg//

Oct 19^th, 2009 at 9:40am

What name polarisation were your told to receive ?

Best regards, Eric.

Oct 19^th, 2009 at 6:18pm

Hello

Grateful for all the assistance. The antenna i am using is a Patriot 1.8m with offset of 22.6deg. With this in mind, you are saying my true elevation should be 33. 4 or there about.

My hub is telling me to use the front arm of the antenna which support the feed to put my angle finder. Is this correct? I normally would use the back support of the antenna in my link star installations.

Keeron

Oct 19^th, 2009 at 6:33pm

That depends upon whether your Prodelin antenna bracket is already stamped with elevation demarcations. If yes, then one must assume they've stamped with offset already factored in. If no, then the page that I referred to you is applicable. This diagram https://www.gdsatcom.com/Prodelin/Technical_Docs/geometry_drawings/OFFSET%20ANTE... may also help put offset in perspective.

//greg//

Oct 19^th, 2009 at 6:45pm

Looking at those pdf drawings, the direction of the beam would be from the lower edge of the dish to the centre of the feed window.

The drawings don't show the metalwork, so I have no idea if the metal support arm has part of itself parallel with this line ?

I suggest you put the antenna front face vertical (e.g. with plumb line). The beam elevation is now 22.6 deg. Put an inclinometer behind the dish in the middle and note that it reads 0 or 90 deg. Now tilt the dish backwards by an amount of 33.4 deg. That will give a beam elevation of 56 deg.

Best regards, Eric.

Oct 19^th, 2009 at 7:47pm

Hello,

We are in Guyana South America.

The manual doesn't really say, but its a Sepatriot antenna Model : TXINT-180KUG we are using.

keeron

Oct 19^th, 2009 at 11:02pm

Elevation: Starting with the front face of the dish upright the front face needs tilting backwards by an amount of 33.5 deg to get a beam elevation angle to 56.1 deg.

Azimuth: approx 114 deg magnetic compass (see blue line on satellite view below)

Polarisation: If your downlink polarisation name is Vertical then make your feed system look like the picture above. The feed needs to be rotated -80.4 deg anticlockwise from a nominal starting position with the LNB sticking out sideways. The viewpoint for the picture is with you standing behind the dish and facing forwards over the top, towards the feed and the satellite in the sky.

One other matter concerns me.

You appear to be at the -10 dB edge of the satellite coverage beam. These beam maps are uncertain particularly in the region of the beam edge. If there is doubt about your signal powers then consider reducing your bit rate by 10 times to at least get it working. You need a PLL type LNB to receive a small symbol rate carrier.

What model number LNB do you have ?

Best regards, Eric.

Oct 20^th, 2009 at 4:00pm

Hello Eric,

We are using NJR 2744H as our lnb, this was requested by our provider.

Regards,

keeron

Oct 20^th, 2009 at 5:21pm

NJR 2744H is a DRO LNB with a local oscillator at 10.75 GHz and stability +/- 900 kHz.

Input freq range 11.7 - 12.2 GHz (good for Hispasat S. America ).
Output freq range 950 - 1450 MHz (good for iDirect).

You have the correct LNB local oscillator frequency.

Did the polarisation image make sense and have you found a satellite yet ? Since you are quite close to the equator, satellites will be in a line going steeply up into the sky from the east horizon. So if you find anything search mainly up or down for the other satellites till you get to the right one.

Best regards, Eric.

Oct 20^th, 2009 at 11:35pm

Hello,

The polarization does make some sense to me since we have mainly had it in that direction during our initial pointing attempts.

The antenna site is 5hrs driving into the jungle from where we are so we need to ensure we have all the concerns ironed out when we next go to the site.

During the initial pointing we were able to get a yellow indicator on the i-Site software but not green. I have purchase a new feed assembly for the antenna and a new i-direct IDU. I will crimp new cables RG6 myself then go back to the site.

If there is anything else you can guide me with it is appreciated.

Keeron

Oct 21^st, 2009 at 12:38am

Quote:

I will crimp new cables RG6 myself then go back to the site.

I strongly suggest you reconsider using crimped connectors. In the environment you describe, exterior grade compression connectors, dielectric grease, and silicone self-fusing tape (or heat shrink) should be employed to protect cable connections.

//greg//

Oct 21^st, 2009 at 8:20am

My concern is the unsuitable Hispasat beam coverage pattern.

I am not hopeful.

If you have been able to find the satellite and peak up and it stays in yellow then it is quite likely that the signal is simply far too low. I'm assuming that the modem was preloaded with an options file or you tuned the modem to the wanted frequency etc using an options file yourself.

Have you tried using the same dish at a different site, further to the north west or to the south east, with any success ? Along the north coast of Venezuela looks good.

If you can't get it to work consider a different service provider on a different satellite. NSS7 Andean beam, for example, would be more suitable.

Central Guyana is 10 dB higher (i.e. 10 times) in NSS7 beam compared with the Hispasat beam.

You don't say what is in your options file regarding bit rate or symbol rate. If the outlink carrier is just for you then it may be possible to reduce the bit rate and FEC coding (e.g. half the bit rate plus 1/2 rate FEC) to get the link just about working. If it is a shared outlink then this may not be possible or reasonable. Even if you do it working (for the downlink) I would expect signal variations due to slight satellite wobble. he uplink has yet to be addressed. I have no idea of the uplink beam pattern. It may be better or worse.

For satisfactory operation, you need about 4-5 dB rain margin under clear sky conditions.

Regarding F connectors, the centre pin must stick out about 2mm proud of the rim, so it makes good contact inside the socket. Sealing against moisture, as Greg says, is of the utmost importance. F connectors with axial compression crimping are not readily available. They must match your cable diameter and cable type exactly. The special axial crimp tool is also rather expensive.

Best regards, Eric

Oct 26^th, 2009 at 1:33pm

Hello Eric,

We travelled to the installation site again, however this time we were unable to find anything. We moved the antenna to an area where the sky is more clear, we followed all you guidlines .

I am wanting to start to believe your concept of a weak signal at our location.

Don't know if you have any other ideas?

Keeron

Oct 26^th, 2009 at 3:11pm

What is tying you to that specific satellite? Can the signal you require be made available from one with better mutual visibility?

//greg//

Oct 26^th, 2009 at 3:11pm

What does your service provider have to say about the downlink and uplink beam coverage and your location in central Guyana ?.

Best regards, Eric.

Oct 27^th, 2009 at 1:26pm

Hello,

Well the provider has some good rates, but i guess i have no other choice but to switch providers, Can anyone suggest some providers that covers this area?

keeron

Oct 27^th, 2009 at 8:20pm

Hello,

Well folks i appears i may have the answer to my problem. My service provider sent me the wrong option file to begin with, in addition to that they didn't mention anything about upgrades to the modem software etc....

So after saying a few hail marys' i decided to calm down and see what they had to say.

keeron

Nov 6^th, 2009 at 12:32pm

Hello,

Unfortunately we still have been unable to point this antenna.

We have an international forest reservation (iwokrama) a few clicks away from the proposed site for the installation.

We have spoken to them and they have indicated they suffer a heavy magnetic interference in the area. They have highlighted that their compass, GPS even their directv solution experienced have intereference while setting up and operations.

How does this affect us? How can we solve this issue and get this antenna pointed?

Any suggestions ?

Keeron

Nov 6^th, 2009 at 1:13pm

Quote:

What does your service provider have to say about the downlink and uplink beam coverage and your location in central Guyana ?.
https://www.satsig.net/images/guyana-hispasat-coverage.jpg
Best regards, Eric.

Even with the correct options file, which sets up the tuning in your modem so you can receive the intended outlink carrier towards you, I don't see how it is going to work with the site on the -10dB beam contour. The signal is almost certainly too weak. What does your service provider have to say regarding your site location and their downlink and uplink beam coverages. Have they told you to look for a different satellite ? (not Hispasat at 30 west orbit position)

Local magnetic compass anomalies should not be a problem. Set up your dish by setting polarisation and elevation accurately, then swing the beam boldly sideways over a wide angle to find the satellite. The direction of the blue line on the map higher up above, out over the river/lake will give you some idea of the direction.

Local interference in Ku band is improbable in such a remote location, especially if surrounded by trees, (except in the direction towards the satellite of course !).

Best regards, Eric.

Nov 6^th, 2009 at 2:15pm

hello,

I am beginning to agree with you on the coverage area. The provider said they tested the beam coverage again and that their tests prove that the coverage area is fine for the 1.8mm antenna we are using.

Anyway i have now decided to test this theory so i moved the antenna to Georgetown which according to your coverage map its 2 layers above the red dot. This should give a better signal strength.

We are attempting to point the antenna in my back yard to see what will happen. I have to take the coordinates which i will post on here to get opinions.

Nov 6^th, 2009 at 3:12pm

Hello,

The coordinate for the test installation is 6.49N 58.07 W.

Based on our calculations our look angle should be:

Az: 90.224
Elev: 56.306
Pol : -76.41

Am i correct so far? Would you say that this is better coverage?

keeron

Nov 6^th, 2009 at 4:28pm

From the Hispasat web site https://www.hispasat.com/media//Hispasat%201D.pdf
this shows:

As you can see the America downlink coverage map is not too clear. My opinion is that Georgetown is very much at the outer edge of the beam and still about -10 dB down on the beam peak, so I am not hopeful (unless you have a small outlink carrier and the hub has turned it up very high). Note there is no uplink coverage map published so even if the downlink just works, your uplink is uncertain.

Your LNB is for the downlink frequency range 11.7 - 12.2 GHz. In your options file it will give the modem tuning, e.g. 1234000000 Hz.
Add 10750000000 (for this model LNB) gives = 11984000000 or 11.984 GHz. If this was true then you would be in red transponder 94, H Horizontal polarisation down.
For Horizontal polarisation start with your LNB side arm sticking directly upwards. Then, step 2, turn it -76 deg anticlockwise (as viewed from behind the dish and facing towards the satellite in the sky.)

The map below

shows azimuth dish pointing aligned with sides of university building.
Note: lat = 6 deg 49 min N, long=58 deg 07 min W

If there is any iDirect service provider reading this and they have a decent coverage of Guyana in the 11.7 -12.2 GHz range, please say.

Best regards, Eric.

Nov 6^th, 2009 at 8:20pm

Hello,

I believe we have covered the angle pretty well, we have some site photos, i will send them to your email to look over.

keeron

Nov 6^th, 2009 at 11:31pm

Hello,

As you suggested the footprint is very small even over our test site. We were able to narrowly find the satellite and bring up the internet on this solution.

After speaking directly with the hub operator, they highlighted that at this site where we want to install the antenna is even further away and less likely to lock onto the network.

They suggested a 2.4m antenna with at least 4W BUC to really get a sufficient signal with no outages in rain.

We have found something on Satmex 6 that will work with the same equipment we are using.

Thanks,

Keeron

Nov 7^th, 2009 at 12:30pm

Satmex 6 Ku2 beam, as shown below, has far better coverage of Guyana.

Satmex 6 is at 113 west orbit longitude. Ask what name is the polarisation for your new downlink. You also need a new options file with new frequency, new symbol rate etc.

Pointing is very different direction, see below:

Best regards, Eric.

Nov 9^th, 2009 at 10:27pm

Hello,

The polarization for this down link is vertical. The elevation for this antenna is almost vertical.

Regards,

keeron Stephens

Nov 10^th, 2009 at 8:21am

If the name of the downlink polarisation is vertical then the starting position for the LNB is sticking out sideways, one side or the other.` Then apply the polarisation adjustment by rotating the feed system 81.7 deg clockwise, as viewed with you standing behind the dish and facing forwards towards the satellite.

For a beam elevation towards the satellite of 27.1 deg, and assuming a similar dish offset angle, the front face of the dish will be approximately vertical.

Have you got it working on Satmex 6?

Best regards, Eric.

Nov 10^th, 2009 at 12:22pm

Hello,

We have the LNB sticking out to the side and we have the antenna at the correct elevation. We have the antenna pointed in the right direction according to dishpointer.com look angle.

We have received a yellow indicator on the i-Direct modem pointing software, with signal strength of between 6 - 7. I believe we are on the satellite however since we had to assemble the feed with all three components, we are not certain that they are aligned properly.

So we have to re-check that and confirm that the feed assembly has been fitted up properly, since we are almost certain that we are pointing in the right direction.

We will work today to complete this appointment.

Regards,

Keeron

Nov 10^th, 2009 at 7:09pm

Quote:

We have the LNB sticking out to the side

With the LNB arm sticking out sideways, to either side, you have set up the feed system to the vertical receive polarisation starting position.

You now need to apply the polarisation adjustment angle. In this case, for Georgetown, Guyana and Satmex 6, a +81.7 deg clockwise movement, as seen with you standing behind the dish and facing forwards towards the satellite in the Sky.

If you started with the LNB arm on the left, the final position will be approximately like this:

Best regards, Eric.

Nov 10^th, 2009 at 9:27pm

Hello,

Great advice guys, we were able to locate Satmex 6 and we were also able to connect with a very good signal strength.

Now its just to move the antenna now to the actual site in the jungle 3.48N 58.41W.

We are taking some pictures of the well pointed antenna with us on the so it shouldn't be hard to emulate.

Thanks

Keeron