Home page of Satellite Internet and Information

Satellite Internet Forum.

Welcome, Guest.
Welcome to this satellite broadband discussion forum. Wherever you are and whatever your problem we are here to help each other. Connecting to the internet via satellite is not always easy but is critically important to those in remote places or with poor terrestrial infrastructure. Both service providers and customers are encouraged to contribute. Register at the bottom of the forum home page if you wish to contribute or ask question. Read the Forum rules.
      Satellite Internet Forum : Home Page          
Pages: 1

iDirect AM22 pointing need help!

(Read 14547 times)
Ex Member
Ex Member


Mar 8th, 2008 at 11:14am  
Hello all,

    I have also posted this in the iDirect forum. I need some help in pointing a dish in Iraq to AM22. My 3000 series has the options file loaded and using iSite software dish pointing I can only get 2.5 volts while pointing. Using a Horizon sat meter for Afg 11.3 Ghz I also can not get a lock and the strongest signal I can get is 69 dB. 

    I have a andrews 1.2m dish and confirmed with bently walker that I have the correct BUC and LNB. They even sent me a picture of a working iDirect in Iraq and my dish setup looks exactly like it. I have double checked the elevation, azimuth and polarity ten times but still connect get a strong signal.  I have pointed antennas and set up systems to W6 and W3A etc so I am not a newbie when it comes to this. Can anyone provide any insight as to what might be the problem?
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #1 - Mar 8th, 2008 at 12:07pm  
Is this the same hardware you were pointing to W3A a while back? If so, was the connection (ever) operational? Have you verified the correct operating voltage is still being delivered to the LNB? In the mean time
http://www.satsig.net/cgi-bin/yabb/YaBB.pl?board=point;action=display;num=116248...
http://www.satsig.net/cgi-bin/yabb/YaBB.pl?board=point;action=display;num=118534...
might hold some insight.

//greg//
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #2 - Mar 8th, 2008 at 12:26pm  
Hello,

    The W3A pointing was for an HX system which is up and running. My other system is a 3000 series on an andrews 1.2 trying to get on AM22. I will try and find a multimeter but I gues my question would be; why wouldn't my LNB be getting the proper voltage? Is that a setting set by the options file?
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #3 - Mar 8th, 2008 at 1:01pm  
Quote:
why wouldn't my LNB be getting the proper voltage? Is that a setting set by the options file?
Well, I have no iDirect-specific training, but consumer grade VSAT LNBs and transmitters (ODU) are typically DC powered. The DC power originates in the IDU (modem) and is carried to the ODU on the coaxial cables. The center conductors physically carry the DC power (supply), and the cable sheathing represents DC return (and signal ground). Many systems use voltage sensing to control polarization; commonly 13v for vertical, 18v for horizontal. Don't know which signal strength meter you're using, but many of them are dependent upon cable voltage for power as well.

Anyway. Compare your ODU readings with those found at the output of the IDU. If it's low at the ODU and good at the IDU, it suggests a cable or connector problem. If it's low at the ODU and low at the IDU, it suggests a modem or power transformer problem. If it's good at the ODU, it suggests a bad LNB.

I don't know if you can specify the output voltage in an iDirect user interface. The systems with which I'm familiar change output voltage based upon the polarization selected (in the user interface).

So. It would be helpful if you could confirm how many volts are present between the center conductor and the connector body on the RX cable. Won't hurt to check the TX while you're at it. Note: depending upon the respective polarizations, they don't necessarily have to be the same.

//greg//
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #4 - Mar 8th, 2008 at 1:50pm  
I as of yet don't have a multimeter but I have tested the cable with the sat meter and the following are my results. Hooking my Horizon HDM V2.5 meter directly to the LNB with a ten foot cable, in a twenty degree elevation and azimuth scan of the sky with the AM22 Afg 11.3ghz meter file, I can only find two satellites.

Using the short cable, I can get one up to 65 dB and one up to 68 dB. I tested with the stronger signal. Hooking up two different 30 meter cables provided by Bently Walker, both cables drop the dB down to 63 dB inside at the modem from 68 dB. I imagine that is just because of the resistance in the longer cable.

Both cables are testing exactly the same. I think the chances of both cables being bad and providing the same results are pretty slim. Tesing outdoors with the shorter cable, if I twist the polarization away from the optimal setting of -13, the dB reading does drop.

Using the iSite software and antenna pointing, the sky is also completely clear and shows .3 volts (nothing) besides the same two satellites. On the satellite that I get a 68 dB reading, I can only peak up to 2.72 volts, but it is a definite signal. I have read all of the AM22 iDirect posts I could find on here and still I do not have a clear solution to what my problem would be.

One guy had the wrong LNB. Bently Walker says I definitely have the right LNB. I have also included some pictures of my ODU. The only thing I can really think of is that my LNB is not working properly?

...

...

...

...

...
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #5 - Mar 8th, 2008 at 1:56pm  
Ohh, and does it matter if the LNB is with the label up like on mine or rotated 180 deg and the label pointing down? (Two possible mounting positions)

Admin:
Just make sure the rectangular aperture of the LNB lines up with the rectangular hole in the waveguide. If there is a thin copper gasket make sure that goes in the right way as well. It does not matter where is the label.
The starting polarisation is defined by the rectangular waveguide. If the broad faces of the rectangular waveguide are on each side that means you are set to horizontal. If the broad faces are on top and underneath that means you are set to vertical.

Regarding the orientation of the LNB arm.  Up the top or down underneath.  Both positions produce a horizonantal polarisation starting position.  The choice may matter if you have to adjust the polarisation by a large angle and find that the LNB or BUC hits the metal yoke or arm.  In which case start from the other 180 deg way.
Back to top
 
 
IP Logged
 
Eric Johnston
Senior Member
***
Offline


Personal text from Profile,
Options, Top line

Posts: 2108
Reply #6 - Mar 8th, 2008 at 2:04pm  
What is the downlink carrier frequency and polarisation you are supposed to be receiving?.

Your LNB is model NJR2754H intended for Input=12.25 to 12.75 GHz LO=11.30 GHz Output=950 to 1,450 MHz

Does the iDirect carrier tuning match with the calculated L band cable frequency = Sat Freq - LNB LO freq?

Does the receive polarisation make sense? Vertical means start with the broad faces of the LNB waveguide on top and underneath. Horizontal means start with the broad faces of the LNB waveguide on either side.

Polarisation adjustment is then about -10 to -15 deg anticlockwise, while facing towards the satellite (for AM22 and Iraq). See Satellite dish pointing in Iraq for exact angles.

From your images you are set to nominal horizontal polarisation, adjusted correctly, approx -15 deg anticlockwise.

You refer to "Horizon sat meter for Afg 11.3". My guess is that the Horizon has been programmed to receive some carrier using an LNB with an 11.3 GHz LO frequency. You don't say what satellite or what polarisation. Note there are four different beams from AM22. The best beam for Afghanistan does not extend as far as Iraq. See http://www.rscc.ru/en/satellite/zones/zone17.html

The Horizon meter is only good for identifying satellites if you know what polarisation and what LNB LO frequency to use.

The tech details of the LNB and BUC are here http://www.njr.co.jp/e_frame/ef_05mc_02.html

Best regards, Eric.
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #7 - Mar 8th, 2008 at 2:18pm  
Hello Eric,

    Here is some more information I can provide, some out of the options file in iSite.

Rx L-band: 1237.09
Rx LNB Translation Frew: 11300

LNB: Model NJR2754H ku_Band Input 12.25 to 12.75 Ghz

The LED: LNB PWR light on the modem is "on".

My elevation info: 48.47
Az: 163.68
Pol: -13.36

Bently Walker's tech told me to use Afg 11.3 ghz sat meter file. I told them I wasn't in Afghanistan and in Iraq. They said it should still work? Isn't that freq not even in my LNB's range? Even so, not using the sat meter, I still canot get above the yellow range of 2.72 volts in iSite.
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #8 - Mar 8th, 2008 at 2:27pm  
Eric,

    I do get the best dB out of the meter while the polarization is set at -13 deg. I have rotated the polarization full range either direction and -13 is the best for dB. In iSite, it does not say anywhere whether I am set for horizontal or verticle.
Back to top
 
 
IP Logged
 
Eric Johnston
Senior Member
***
Offline


Personal text from Profile,
Options, Top line

Posts: 2108
Reply #9 - Mar 8th, 2008 at 2:32pm  
You need to be told by BW what polarisation to use. The modem and iSite can't affect or alter the polarisation.

You are listening to Horizontal polarisation at 11300 + 1237.09 = 12537.09 MHz.

If you don't know what polarisation to use then try turning the feed 90 deg. It is either correct where it is now, at -13 deg, or needs turning 90 deg from where it is now.  Sweep the sky again in case it was the wrong satellite.

Does your elevation scale (roughly) correspond with 48.5 deg elevation. Looking at the images it appears that your elevation may be more like 60 deg but it is hard tell from the image viewpoint.

Best regards, Eric.
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #10 - Mar 8th, 2008 at 2:42pm  
Eric,

    Ya, I turned the feed 90 deg all directions and it did not help, the signal weakened. I have pointed Bently Walker techs to this thread so hopefully I can get some more spotlight on this.

With my dish being on tall hesco dirt holding baskets, it's hard to get level pictures from the sides. The dish is set exactly at a 48.5 deg elevation. From this setting I have scanned the sky 20 deg off in both elev and azimuth. I can only find these two satellites in the swing with both the sat meter and any voltage readings in iSite. I am pretty sure one of the two is AM22 but like I said, I can't commision the modem if the LNB  is getting such little voltage for some reason.
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #11 - Mar 11th, 2008 at 2:44am  
Is the dish pointing towards any microwave towers?  Any antennas that transmit at about 12 Ghz would weaken your reception.  Check this link about Terrestrial Interference:  http://www.geo-orbit.org/sizepgs/Noise.html

Could they be jamming radio waves there at the base?
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #12 - Mar 11th, 2008 at 4:28pm  
Satbaja,

     My diss is pointing out into the open desert. All of the antennas are behind my dish. My base has about 200 satellite dish's working so hopefully there is not much interference.

I searched again for AM22 today but I could only manage 5 volts. Thisw is after Bently Walker sent me a new options file.
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #13 - Mar 12th, 2008 at 7:22am  
If your horizon meter is not pre-programmed for a frequency on the AM22 53E steerable beam 2 that covers Iraq, you can't depend on the meter to ID the satellite.  The main beam (European beam) is very weak in Iraq.

I saw on horizon's website they have AM22 Horizontal and Vertical files for the latest version of their meter.  No mention here if that one IDs the steerable beam 2.  Since 2 of the 4 beams on AM22 do not cover Iraq well you are better off using isite for the antenna pointing and identification.

Looks to me that your dish is set up properly.  You want to make sure the OPT file is correct for your transponder.  Does your option file have the following two parameters?  If so, what values are listed?  You can open the option file with a text editor to look at the parameters.
rx_freq =
rx_acqrange =

Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #14 - Mar 18th, 2008 at 12:59pm  
Bently Walker did some config settings with myself. They said they had loaded it with W6 iSite and not AM22. Once that was corrected, he also double checked the modem parameters through telnet. In theory, I should now have had no trouble finding the sat.

But to no avail, I can still not get above 5v in iSite antenna pointing. The Sat meter says it's AM22, I get the highest voltage (5v) out of that sat in iSite, it's the correct elevation, azimuth and polarity.

I am at a loss, very frustrating.

Satbaja:

rx_freq = 1237090000
rx_acqrange = 1800000
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #15 - Mar 19th, 2008 at 2:45am  
rx_freq = 1237090000
rx_acqrange = 1800000

That 1800000 is correct for your LNB.  The number is calculated from the stability factor of the LNB.  Yours is 900KHz  giving a range of 1800KHz

A high quaulity LNB would have a range of 10KHz or 50KHz.  The acqrange tells the iDirect modem about the specs of the LNB so the modem locks on the frequency.   

Some LNBs work outside their specs.  If your LNB actually has a higher stability range than the stated 900KHz, it may help to widen the range.  You should replace the LNB with another similar model that works within specs.

Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #16 - Mar 23rd, 2008 at 8:14am  
I still can only get a maximum of 5 volts, increasing the arc range did not appear to change anything.

Would anyone else have an idea why it would be this hard to get the proper voltage? Could I have bad equipment?
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #17 - Mar 23rd, 2008 at 2:11pm  
If I had a bad LNB, would I not show strong signals with the sat meter? I do get strong signals. 

Also, I have a question about the iSite antenna pointing software. When I start it up, it says to start the sweep 20 deg off of planned azimuth. I sweep the dish over and I find the sat but only 5 volts at peak up. Now if I shut down iSite and start her back up and with the dish not moved, the same sat will show .3 volts or baseline. Is that normal? 

Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #18 - Mar 23rd, 2008 at 9:19pm  
Update: I hired a local tech here on the camp to come over and take a look.

He had a different kind of sat meter then I have but also found AM22 in the same location I had. He tested both 30m cables with a voltmeter leading to the dish and all four leads tested good. He double checked some settings on the modem and in iSite, options file etc.

Like I, he could not get a lock with the modem. No green lights and only 5 volts in iSite antenna pointing. Needless to say, the issue is not resolved and I am out some money.

So what would you all think are my options? Could the modem iteself be bad? Bently Walker offers iDirect also on W6. I could swap out the LNB and BUC. I know for sure I can get W6, I have a DVB-S2 system running on this same dish before. But if the modem is bad, obviously switching satellites won't change a thing.
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #19 - Mar 24th, 2008 at 6:00am  
though it sounds too simple to be true, but I would recommend you to ask your provider for an updated option file. I remember at least three cases (two with one provider and a third with another), that customer could not get a lock on the signal. Apparently, the signal from the hub was modified (the bandwidth was increased on three cases), and the tech support did not think to mention it nor to send an updated option file.
Back to top
 
 
IP Logged
 
Ex Member
Ex Member


Reply #20 - Jun 9th, 2008 at 7:05pm  
I had a similar problem in Mozambique where I knew for a fact I was spot on the sat but could not push more than 4V . I eventually changed the LNB and problem was solved .
Back to top
 
 
IP Logged
 
Pages: 1