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Need help pointing to T11N

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dewholden
Ex Member


May 17th, 2012 at 2:13pm  
Hi. I am currently working on setting up a vsat system from globaltt.com and it needs to be pointed at T11n.

I am using a Maxpeak Sam-lite2 meter. I am currently getting a reading of 77 dbuv, but the meter will not lock onto the signal.

I have two other sites where the signal is at 77 dbuv and 80 dbuv, both of which locked on to the T11n signal with 100% signal strength.

With the current site, I can't get the meter to lock onto the signal at all, even after much trial and error of changing the azimuth, elevation and even the polarization angles at small intervals at a time.

What should I be looking at to troubleshoot this?

Thanks!
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Eric Johnston
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Reply #1 - May 17th, 2012 at 4:52pm  
Check your meter tuning and symbol rate, the LNB type and LO freq, polarisation and check that the carrier you are looking for has not changed recently.

If there are equal sized carriers on both polarisations you will get an unchanging power meter reading all the way round. Set the polarisation name initially and then adjust by a calculated amount.

If all is OK you may be peaked up on wrong satellite.  What carrier frequency are you looking for ? What LNB LO do you have ? What polarisation name?  Where are you (lat/long)?

While peaked up now, mark the angles on the mount so you can always get back to this 'first found' satellite.  Can you indentify this satellite by examining the other carriers ?

Measure the elevation angle.  Is is a few deg low or high ?
Try the next satellites along the orbit each way.

What happens if you connect the VSAT modem instead of the meter ?

Best regards, Eric.
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Space
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Reply #2 - May 26th, 2012 at 6:22pm  
Hi

Give me your number  and i shall call you ,  We also have a platform On t11  and  we cold help you  get Lock

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dewholden
Ex Member


Reply #3 - Aug 2nd, 2012 at 4:31pm  
Hi Eric, Unfortunately this is still an issue. I was very ill for quite some time but am now back at work and need to get this up and running. Unfortunately I am not an expert at this, the previous  installations from this supplier went so smoothly that I had no need to troubleshoot at all.

Can you help me out with an explanation, or a link that I can go to to understand what each of the following are, so I can supply you with the info:

symbol rate
LO freq
carrier frequency
polarisation name 

We are at: 14.917701 degrees south, 13.490017 degrees east, altitude of 5800 ft.
The elevation of the dish is slightly lower (26 degrees) than that which was recommended by the operator (29.93 degress)
With the maxpeak meter, it only gives me a reading when it locates the T11N satellite, based on settings that are downloaded from their website.
When I connect the iFast modem, it doesn't show any signal at all, on the web interface it provides.

Thanks for your help.

Regards,

Daniel Holden
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Oasis Networks
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Reply #4 - Aug 2nd, 2012 at 7:34pm  
Dear Daniel,

From your GPS location, it looks like you are in Lubango.

If you want, we have at the moment an engineer in the area (at the moment between Namibe and Lubango), and we can help you point the dish if you want.

Please contact me offline you would like a professional assistance.

Kind regards,
Nimrod
nkapon@anarf.com
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Eric Johnston
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Reply #5 - Aug 2nd, 2012 at 7:52pm  
You need to talk to your service provider: globaltt.com

Regarding these items:

Symbol rate
This refers to your downlink wanted carrier.  The symbol rate of a digital carrier is approx the same as the bandwidth of the spectrum shape at the -3.5dB points.  See this example: http://www.satsig.net/spectrum-dvb-satellite.htm  The shape is similar even if the carrier is much smaller like 1 Msps, with a bandwidth of 1 MHz at the -3.5 dB points (approx). Note that the transponder bandwidth occupied by a carrier is approx 1.4 x symbol rate.
You need to set the symbol rate in your modem.

LO freq
This refers to the LNB local oscillator frequency. Note the type and model number of your LNB and find the technical specification.  Some LNBs have one LO frequency.  Some LNBs have two LO frequencies, one of which may be selected using a 22kHz tone (on or off) or LNB voltage selection (+13 or +19V) in your modem. Typical local oscillator frequencies are listed here http://www.satsig.net/lnb/explanation-description-lnb.htm
Examples 9.75, 10, 10.6, 11.3 GHz
What is or are the LO frequencies of your LNB ?
LNB means "low noise amplifer and block downconverter".
 
Carrier frequency
The carrier coming down from the satellite has a frequency like 11.123456 GHz (Ku band).
The carrier frequency that your modem sees as it comes down the LNB cable is much lower, in the range 0.95 - 2.1 GHz or, more normally, expressed as 950 - 2100 MHz.  Some modems only work 950-1450 MHz.
To convert the satellite frequency to the L band cable frequency subtract the local oscillator frequency.
For example:
Satellite freq = 11.123456 GHz = 11123.456 MHz
LNB LO freq = 10.0 GHz or 10000 MHz
Cable freq = 11123.456 - 10000 = 1123.456 MHz
Tune your modem receiver to 1123.456 MHz
 
Polarisation name and adjustment amount
This refers to the polarisation of the signal from the satellite, as it leaves the satellite, relative to the equator.  If the polarisation name is "Vertical" (north-south), this means that the broad faces of the LNB rectangular input waveguide should initially be oriented facing up and down, like so:
...   ... LNB waveguide vertical polarisation starting position.

From your location in the southern hemisphere, T11N is (approx) to the north west.  You need to adjust the polarisation by an amount of  -72 deg anticlockwise, as viewed facing forwards towards the satellite in the sky.  No adjustment would be needed if your wanted satellite was exactly due north of you. For satellites to the north east (approx) the adjustment would be clockwise.

The blue line shows the direction to point your dish:
...
Ref: http://www.satsig.net/maps/satellite-dish-pointing-west-africa.htm
wxw
Best regards, Eric.
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« Last Edit: Aug 21st, 2012 at 9:40am by Admin1 »  
 
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dewholden
Ex Member


Reply #6 - Sep 20th, 2012 at 10:32pm  
Globaltt.com tells me:

symbol rate: 10000
LNB LO Freq: 10 GHz
carrier frequency: 11080 MHz
polarisation name: horizontal

From what I understand, when I configure my meter, I need to set it to search for 11080 MHz - 10000 MHz = 1080 MHz?
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Oasis Networks
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Reply #7 - Sep 21st, 2012 at 12:25am  
Yes, this is correct.

Make sure as well that your meter provides DC to the LNB, and check as well the 22Khz tone. Some LNBs will change their LO frequency according the 22Khz tone presence.

Good luck
Nimrod
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dewholden
Ex Member


Reply #8 - Sep 21st, 2012 at 9:16am  
Hi Space.

+244-925-666-897

Any help is greatly appreciated.

Quote:
Hi

Give me your number  and i shall call you ,  We also have a platform On t11  and  we cold help you  get Lock


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dewholden
Ex Member


Reply #9 - Sep 21st, 2012 at 11:34am  
Quote:
Yes, this is correct.

Make sure as well that your meter provides DC to the LNB, and check as well the 22Khz tone. Some LNBs will change their LO frequency according the 22Khz tone presence.

Good luck
Nimrod


ok, so I tested these settings and my meter (http://www.maxpeak.tv/samlite.php) is now telling me that I am getting 82 dbuv, which is the best I can get.

Frequency: 1080 MHz
Orbital Position 37.5 West
Polarization: Horizontal
Symbol Rate: 10000
FEC Inner: Auto
Low Band: 22 Khz on
Dig. Nyquest Root Filter (Rolloff): 0.35
LNB: 10 GHz

I also tried an alternat configuration of the meter using Low Band: 22 Khz off, with exactly the same results.

Even with the meter showing 82dbuV, my skyedge II modem shows me no signal at all.

Any ideas?

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Eric Johnston
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Reply #10 - Sep 21st, 2012 at 11:44am  
Check your polarisation.

For Horizontal name..

Start with true Horizontal polarisation. Set the LNB filter side arm directly upwards.

Adjust by an amount of -72 deg anticlockwise, as viewed facing towards the satellite in the north west.

Best regards, Eric.
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dewholden
Ex Member


Reply #11 - Sep 21st, 2012 at 11:58am  
Hi Eric, would the fact that this dish is dual-optic affect the direction of the polarization or is that irrelevant? I'm asking since the receiver is pointed at the smaller relfector, in the direction of the satellite, not back towards the main dish.

This is the dish I have:

http://www.visiosat.com/home/vsat/product-detail.php?cat=18&id=245
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dewholden
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Reply #12 - Sep 21st, 2012 at 4:11pm  
Eric Johnston wrote on Sep 21st, 2012 at 11:44am:
Check your polarisation.

For Horizontal name..

Start with true Horizontal polarisation. Set the LNB filter side arm directly upwards.

Adjust by an amount of -72 deg anticlockwise, as viewed facing towards the satellite in the north west.

Best regards, Eric.


Hi Eric,

Did this, but no change.

Regards,

Daniel
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modi
Ex Member


Reply #13 - Feb 26th, 2014 at 11:28am  
Hi!
Did you finally found why you did not locked on the satellite? We are facing the same problem here with that satellite and same provider.
They told us: Freq= 11119 GHZ Pol Hor. LNB 10 GHz with 18 V. we are using Satlook Micro. We have a good signal, we even have Internet as you've just moved the dish from a previous location. But this time the Satlook is not locking on the satellite, so we can't see BER, UCB, CB, etc... to really fine tune. But Internet is working, even not as good as it should.
Please, need help locking the satlook on T11n.
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