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Need help aligning dish in Balad, Iraq

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dimych
Ex Member


Nov 10th, 2008 at 3:45pm  
We are on the East side of the base, and trying to get to the W18 (IntelSat 901)

I've attempted every step listed here as troubleshooting for folks that had issues aligning, went through degree-by-degree incline and decline of the dish to get +- 10 degrees to the original offset, while swinging dish from side to side "wildly".  iSite doesn't even get static, and all I get in the command prompt window is 0.30000, the light just blink amber Tx and Rx.
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Eric Johnston
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Reply #1 - Nov 10th, 2008 at 6:18pm  
You say "iSite doesn't even get static"

Sounds to me as if the LNB is not connected.

Check the receive LNB cable. 

Possible problems: 
TX and RX cables are crossed over.
Centre pins not long enough,  should stick out proud of the surrounding rim by 1.5mm
Centre pins not pushed into socket; when inserted make sure it really goes in and does not push back the cable.
Braid open circuit.  Braid must make good contact inside plug outer.
Centre to braid short.  Use magnifing glass to examine for possible spurious fragments of braid wire.

Test with DC voltmeter at LNB end to check for DC voltage supply.

In the modem options file check that the outdoor unit receive (LNB) power supply is turned on.  To lock to the outlink carrier you need an options file with the correct outlink carrier frequency, symbol rate etc.  What has your service provider sent you ?

Best regards, Eric.
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dimych
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Reply #2 - Nov 11th, 2008 at 7:59am  
Cabling seems to be fine, center pins are good, cable doesn't push back, TX and RX cables aren't crossed over (got those labeled), will try to get a voltmeter to get the voltage at the exit end of the cable.

Power lines:
[ODU]
     music_present = 0
     odu_rx_dc_power = 0
     odu_rx_10_MHz = 0
     odu_tx_dc_power = 1
     odu_tx_10_MHz = 1
     odu_disable_tx_pwm = 0

.opt file loaded into modem, had the proper version (8.0.2.1) for both file and software.

From modem params:

     rx_freq = 2147483648
     rx_acqrange = 2000
     rx_bitrate = 9074355
     rx_mode = 2
     rx_modtype = 1
     rx_fecrate = 15
     rx_scram = 1
     rx_diff = 0
     rx_specinv = 0
     tx_freq = 1000000000
     tx_bitrate = 686562
     tx_mode = 0
     tx_modtype = 1
     tx_clksource = 0
     tx_fecrate = 5
     tx_scram = 1
     tx_diff = 0
     tx_specinv = 0
     tx_power_in_dbm = -8.000000
     rx_fsd = 63184
     tx_spreading_factor = 1
     rx_spreading_factor = 1
     is_demod2_active = 0



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Eric Johnston
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Reply #3 - Nov 11th, 2008 at 9:58am  
odu_rx_dc_power = 0
Your LNB power supply is turned off

Get your service provider to generate a new options file for you with
odu_rx_dc_power = 1

and to check all other parameters at the same time.
These look improbable to me:
rx_freq = 2147483648  
rx_acqrange = 2000
rx_bitrate = 9074355

tx_bitrate = 686562

Tell your service provider the make and model numbers of the LNB and BUC you have, as it is important that the
[FREQ_TRANS]
     down_translation = xxxxx.000000
     up_translation = 13050.000000
are correct.  Ku band sites have a variety of LNB local oscillator translation frequencies to suit the part of Ku band where is the wanted outlink carrier.

For example:

     Satellite downlink 12,508,000,000 Hz (12508 MHz)
minus LNB LO frequency - 11,300,000,000 Hz (11300.000000 MHz)
equals Modem tuning    =  1,208,000,000 Hz ( 1208 MHz)


Transmit Ku band BUCs normally have LO=13050.000000 MHz.


Best regards, Eric.
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dimych
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Reply #4 - Nov 11th, 2008 at 10:37am  
[FREQ_TRANS]
     down_translation = 0.000000
     up_translation = 13050.000000

Hmmmm....

Serverside config file? heh...
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Admin1
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Reply #5 - Nov 11th, 2008 at 10:43am  
They seem to have issued you with a bad options file, but I don't know if it is a good options file for their hub equipment.

You may be tempted to turn on the LNB supply yourself but I suspect that if you amend the options file locally your modem will at some point automatically reload the master options file from the hub and you will be back where your are now with no service.  So it is important to get the hub involved and for them to make a good options file and sent it to you.

When you say the type/model of your LNB I will amend the text above for your actual LNB local osc freq,  could be 9.75, 10, 10.6 11.3 GHz etc.

Best regards, Eric.
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dimych
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Reply #6 - Nov 11th, 2008 at 11:04am  
My LNB is GM-6933
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Reply #7 - Nov 11th, 2008 at 1:02pm  
See here for LNB spec:
http://www.fujitsu-general.com/global/products/lnb/lineup/ku_dro.html

GM-6933 is suitable for 12.25-12.75 GHz. Lo=11.3 GHz, Modem cable 950 - 1450 MHz.  Stability is +/- 500kHz

Check with your service provider that your outlink carrier is in range 12.25-12.75 GHz. The options file rx_acqrange  needs to be adequate for +/- 500 kHz

Best regards, Eric.

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dimych
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Reply #8 - Nov 18th, 2008 at 5:40pm  
I'd like to thank everyone who contributed.  Our LNB was not compatible with the new satellite provider.  Now that I got a new one, I can't see anything in the iSite, but I can see numbers crunching away in the terminal window when I turn on dish alignment application.

so... What am I looking for in those numbers?  I can't seem to get anything under 0.3000 or over 3.15....

I can't get a lock on the satellite either - lights just flash amber, no green comes on.  I've been swinging the thing left and right for quite some time - no luck.


Probably satellite's too low for my location, as I need to have a negative 3 degree angle, and my dish's pointing slightly to the ground... ground has big barriers, but they're not in line of sight of the dish... a bit odd.

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Eric Johnston
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Reply #9 - Nov 18th, 2008 at 6:03pm  
Ok.  You have new LNB.  What is its model number ?  What tuning frequency and symbol rate are you now trying in the options file ?

What polarisation name have you been told to use for the downlink ?

Using satellite dish pointing iraq and aiming at IS901 at 18 deg West the elevation is low but above 10 deg, which is my recommended lower limit for Ku band operation.   The azimuth is rather south westwards and if you are on the east side of the site you may have buildings in the way.  This image below will give you the idea:
...
If you look at a large scale view on my Google map you may be able to see your building and the new blue line I have added to show where the beam goes.

Put your eye behind the lower rear edge of the dish next to the feed support arm and sight just over the top of the feed horn aperture.  Is there a clear view for the beam ?

Best regards, Eric.
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dimych
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Reply #10 - Nov 19th, 2008 at 5:52pm  
We ended up raising a dish another few feet and got a lock a few minutes into swinging.  

Again, I really appreciate all the hints and tips and bearing with our whining.

Now, is there a "good" set of numbers I should look for with "acq on"?  I can't seem to find any info on what those numbers mean and whether or not it would assist me in fine-tuning the dish.  I get stable 15v signal, but seeing as our speeds are slightly faster then 15kbps up or down, I'd like to try and fine-tune it.  Support says there's nothing they can do to assist me with that, as all they look at is current voltage, and they're satisfied with it.

Currently there are 5 users on the network, and we're on 10:1 plan 1024x256, which SHOULD give us reasonable speeds in off-time, alas...  I can load a webpage (30 secs for google.com), but anything along facebook, or any other stupifying graphic-intensive stuff takes over 3 minutes a page to load.
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