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Telstar12 from Iraq

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Jul 17th, 2008 at 5:52pm  
Are there any special precautions on using Telstar 12 (15 W) from the Baghdad area?

P.S.

1.8m/3W BUC
Elev.=17 deg.
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Reply #1 - Jul 21st, 2008 at 4:10pm  
What precausions would you be impling? We use it everyday. Works great.
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Reply #2 - Jul 22nd, 2008 at 1:41pm  
Quote:
What precausions would you be impling? We use it everyday. Works great.  


I am not impling anything, I am sure T12 does not need a vote of confidence.

Rather, I am after helpful advice regarding a link budget and the max  return bps using a 1.8 meter reflector + a 3W BUC from the Baghdad area on an iDirect platform, elevation 17 degrees.
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Eric Johnston
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Reply #3 - Jul 22nd, 2008 at 2:44pm  
The most important precaution regarding any satellite is not to transmit unless you are in phone communication with the hub who are watching for your low level carrier on a spectrum analyser, to verify if you are on the correct satellite, and on exact polarisation angle and frequency.

At low elevation angles particularly, you should take local precautions to avoid people getting themselves into the beam to the satellite. I can think of other important precautions, like avoiding dropping tools on people below.  So wear a hard hat (applies to people on the ground also), tie off ladders etc.

I can't think of any precautions peculiar to Telsar 12.

If the question is about link budgets then read on...

Use this satellite range calculator to find the range=39900 km approx from you to the satellite.

Use this http://www.loralskynet.com/pdf/telstar12_pamphlet.pdf to find the uplink satellite receive G/T = + 2.6 approx.

Note the uplink PFDsat for the various gain serttings.  Note the downlink saturated full transponder eirp also. You will need to take off the output back off and subtract 10 x log(carrier bandwidth/transponder bandwidth)

Using the above calculate uplink satellite link budget to give you an idea of what C/Nup is possible at the satellite using various carrier bandwidths.  Does it look feasible ?

Contact the satellite operator to find where there is spare transponder capacity on whatever beam to beam inter-connectivity you want, e.g. Europe to Europe, Europe to US etc.
Find the transponder gain step setting for the particular up beam to down beam configuration and the satellite operators desired operating point (i.e. Back off in versus Back off out, for multicarrier operation)
Determine the downlink eirp, by proportion of the whole transponder, for whatever uplink pdf you can create.  Input your idea for hub receive dish size, location of hub in downlink beam etc.  Estimate some uplink and downlink interference, plus transponder intermod interference (normally -21 dB) and you have your answer in terms of overall C/N for a some chosen carrier bandwidth.
Now review what your iDirect return link hub burst receiver needs in terms of Eb/No and C/N (I don't know the modulation method and FEC options.)   This Eb/No calculator may be of use.  Apply some suitable rain margin (say 5 dB) and the result is what you want.

Maybe someone already operating to Telstar 12 with iDirect can say what is their experience of uplink bit rate, hub burst receive Eb/No and rain margin for dish size and BUC power rating.
wxw
Best regards, Eric.
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Reply #4 - Jul 28th, 2008 at 7:40pm  
With a 1.8 3 watt, depending on what transponder you are on you should be able to get away with a 1024 rtn link, So up from your remote to the Teleport.
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Reply #5 - Feb 12th, 2009 at 3:21pm  
Hi et3sgh,

If you are interested you in our teleport services from the Netehrlands, you could base your link budget on a 9m Ku-band dish in Burum, the Netherlands (antenna known to Telesat).

Rgds
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Reply #6 - Feb 12th, 2009 at 3:23pm  
Forgot the contact details
www.castor.nl
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Reply #7 - Feb 21st, 2009 at 1:00am  
If your VSAT/remote end is Iraq where do you intend to to uplink from?  CONUS?  Europe?  ME? (ME and CONUS are a stretch, but doable)

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