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what spectrum analyzer?

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Mar 5th, 2007 at 6:08pm  
Hello, all

I'm new on satellite universe, just starting to learn...and i've learned a lot in this forum.

I'm planning to build two trailers for on location internet acces with wifi wireless distribution, so i'll need to point the sat, everyday.

They will work with 1.2m dishes, manual pointing.

I'm learning about sat finders and spectrum analyzers.

Can somebody suggest me the better relation quality-price spectrum analizer ?

I live in Uruguay, and they cost a lot, so "any penny counts", but at the same time, the unit cannot fail, i can buy in USA.

Need i give more info ?

Any suggestion is very much appreciated.

Thanks a lot for yours oppinions.

Fabian Oliver
Uruguay
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« Last Edit: Apr 19th, 2007 at 8:05pm by Admin1 »  
 
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Eric Johnston
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Reply #1 - Mar 5th, 2007 at 11:03pm  
You will find that the satellite modem (LinkStar, iDirect, Shiron, Vipersat etc) all have a green LED display indicating successful reception of the satellite downlink carrier, plus a relative quality indicator like Eb/No or Bit Error rate.  

You set the beam elevation and polarisation by calculation and then swing the dish boldly in the general direction and find the satellite on the first swing.  Then peak up with fine adjustments using the Eb/No or BER readout.  Make sure that RX LED and signal quality measurements are visible to the person moving the dish.

A spectrum analyser is not necessary.

Best regards, Eric.
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Reply #2 - Mar 5th, 2007 at 11:40pm  
Hello Eric, thanks for your response.
In Satelite internet-Americas i've post this this morning:
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Hello all.
It's my first post and i'm new on satellite universe.

I'm close to buy a system to have movil internet, moving all days to work with.

In my country ( Uruguay) the only seller of products and satelite services is Antel ( national telephone enterprise), they have an agreement with Hispasat satelites, so no choice.

In Hispasat manuals of dish instalations they use spectrums analyzers to point the dish, so the seller here advice to me that the sat finders are not sure tools, "you can think you are wright but you are pointing another close satelite, not yours".

I would like to know if this is true, because may be i need to build more than one satellite unit, and it will turn very expensive if it's the case.  

Can i find a very reliable sat finder, or no way? witch brand and model?

Thanks for your opinions.
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May be it explains better you my situation.

The modem will be Nera Satlink 1000.

I was told by argentinian providers that with sat meters will be enough to point the dish.

My concern is that i'm going to provide wifi signal to other people with this systems, so i need to have a sure set-up.

Thanks again.  Fabian
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« Last Edit: Mar 6th, 2007 at 11:25am by Admin1 »  
 
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Reply #3 - Mar 6th, 2007 at 11:15am  
Inexpensive satellite meters see: http://www.sadoun.com/Sat/Order/Signal-Meters.htm measure all the power in the L band cable, just like an untuned crystal set.  It is just a broadband power meter.  They are good for locating satellites with lots of big high  power carriers.  They don't show much however if the satellite has negligible traffic on it.  They give an indication as you pass each satellite and allow you to peak up quite well, particularly if the meter has two voltage ranges.   The meter does not tell you which satellite is which and it is quite normal to peak up on the wrong one and have to repoint to the next satellite and so on till you come to the right satellite.

"Satellite identifiers" have a simplified satellite TV receiver built in plus some database with a list of satellites and details of a TV carrier on each.  These identifiers work well if you are regularly using the identifier on the same satellite and you have successfully used it before.   First time use can be unsatisfactory however as it may lock to a similar TV carrier on a wrong satellite and it will not work at all if you misunderstand the polarisation or LNB LO frequency that was used when the database program was prepared.   If you know for certain that there is a reliable satellite TV program downlinked on Hispasat, on the same polarisation as your service then a "satellite identifier" is a possibility.  Make sure it was programmed with the particular LNB LO that you will be using.  Having such an identifier will simply save you having to look down into the vehicle to see the satellite modem or PC screen.

A spectrum analyser is an excellent tool for dish alignment and investigating problems.  It does not tell you which satellite is which however unless you know what each satellite spectrum looks like see: http://www.satsig.net/spectrums-europe.htm for example.  

I think your concern about the detecting the satellite signal is misplaced.  You must simply set your polarisation accurately by calculation and can then find the satellite and peak up the azimuth and elevation perfectly using the modem RX LED and the Eb/No or BER readout.

Best regards, Eric.
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« Last Edit: Mar 16th, 2015 at 5:23pm by Admin1 »  
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Reply #4 - Mar 6th, 2007 at 12:13pm  
Thanks Eric for your time,

Your post is very clear, i'll continue to read on your links.

Wednesday (tomorrow), we are going to make a test with the internet provider, with all the system,including dish pointing, a wireless router and 5 notebooks to see if the "speed" of the system is enough, and how it works.


I'll come back with some coments later.


Fabian
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Reply #5 - Mar 6th, 2007 at 12:47pm  
I am interested to know also.

I would estimate, as a minimum, that you need dedicated 50kbit/s down and 20kbit/s up for 5 PCs or the shared equivalent such as 500kbit/s down and 200kbit/s up shared 10:1

Best regards, Eric.
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« Last Edit: Mar 6th, 2007 at 2:24pm by Eric Johnston »  
 
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