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Satellite Antenna Pointing Aid Equipment

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wow
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Jan 8th, 2009 at 5:19am  
Hi,

Can anyone recommend any good Satellite Antenna Pointing Aid Equipment?

Normally what type of input signals that this type of pointing aid equipment use? Pls kindly advice.

Best Regards,
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Eric Johnston
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Reply #1 - Jan 8th, 2009 at 9:18am  
Angle measuring equipment:

Inclinometer:  If your elevation bracket does not have a scale then an inclinometer is useful. Try to get one that has a readout to 1 deg accuracy. You can make one yourself by following instructions here: how to make an inclinometer  You can also use the inclinometer sideways across the LNB or BUC to set the polarisation.
Another method is a plumb bob (nut on string) plus a measuring rule and a set of tan/cos/sin tables (or use Start, All programs, Accessories, Calculator, Scientific mode)

Magnetic compass:  Accuracy is not normally important, unless you are aiming to just miss the side of building, for example. See:How to use a compass If the sun is out you may be able to judge the bearing adequately without using a compass.

Satellite signal measurement:  

All VSAT modems incorporate a receiver which will display noise and signals from the LNB.  If corrrectly configured, the modem will show a green RX LED when the wanted signal is detected and a readout via a PC screen to tell you the signal quality (e.g. Eb/No or BER).  You need to peak up exactly.  Turn the adjuster in 1/6th turn steps and record. Then adjust to the exact centre.  Or, find two exactly equal low quality measurements either side and then move the dish to the centre.  The disadvantage is that you need the modem / PC temporarily at the antenna.

Simple power meters.  Costing under $50 these in-line "crystal sets" measure noise and will detect noise from the warm ground, the sun and satellites.  You can peak up on anything - but there is no certainty that you are on any particular wanted satellite. Advantages: cheap, portable, powered via the modem LNB DC supply, no misunderstanding of what it means.

Satellite TV detectors.  There are more expensive meters that incorporate a simplified digital satellite TV receiver.  These need pre-programming to correspond to known operating DVB-S carriers on particular satellites, on particular bands (C, Ku low, Ku high) and particular polarisations and with particular LNB local oscillator frequencies.  If correctly programmed and you have the matching LNB and polarisation set then they are excellent.  Ideal is you are regularly setting up the same system. If you deal with a variety of satellites you must be very organised about preparing the programming and finding out what DVB-S carriers are actually active (if any) on what satellites, polarisation, frequency and LNB LO freq.  Fortunately such meters also operate in "simple power meter" mode if they don't recognise a satellite.  Advantage: Portable and include battery power.  Disadvantage: Possible to get you frustrated/confused/angry !. See examples: http://sadoun.com/Sat/Order/Signal-Meters.htm

Spectrum analysers are similar to simple power meters but show the noise level spectrum on a screen display. See my on-line satellite spectrum analyser for spectrums of satellites either side of Europe. If you have known reference spectrum plots you can identify satellites.  Good for resolving side-lobe, interference and cross-pol problems.  Disadvantage: Expensive ($1000 - $25000), heavy.  Be careful not to get DC applied to the input of sensitive analysers.  A DC block is a useful gadget for the spectrum analyser input socket.

An L band splitter with DC block on the measurement path is a useful aid.
...

The input signals to the signal measuring device are from the LNB output and are in L band, typically 950-1450 MHz or 950-2150 MHz.

Best regards, Eric.
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« Last Edit: Jan 8th, 2009 at 10:32am by Eric Johnston »  
 
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wow
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Reply #2 - Jan 8th, 2009 at 3:29pm  
Hi Eric,

Thank you very much for the detail explanation. I have tried to find a digital satellite meter but  most of them are doing antenna pointing using DVB signal.

Is there any Satellite Meter that can use the satellite's beacon or modulated carrier to do the antenna pointing ?

Best Regards,
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Eric Johnston
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Reply #3 - Jan 8th, 2009 at 3:49pm  
Quote:
Hi Eric,
Thank you very much for the detail explanation. I have tried to find a digital satellite meter but  most of them are doing antenna pointing using DVB signal.

That is quite true.  There may be no suitable DVB-S carrier in the beam/satellite that you are looking for or the information you are told about a DVB-S carrier, its polarisation or frequency band may be wrong.

Quote:
Is there any Satellite Meter that can use the satellite's beacon or modulated carrier to do the antenna pointing ?

Best Regards,

Beacons are low power.  To receive a beacon you really should use PLL type LNB and narrow band filtering which implies an expensive, high stability, spectrum analyser.

If you want to receive and make measurements of a modulated carrier then use the intended receiver.  If you are installing iDirect then maybe take your own iDirect modem which you take with you and use at the antenna, with a laptop. Alternatively, a 30m length of ethernet cable from the customer modem back out to your laptop at the antenna would work.

Best regards, Eric.
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« Last Edit: Sep 14th, 2015 at 9:57pm by Admin1 »  
 
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wow
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Reply #4 - Jan 8th, 2009 at 4:07pm  
Hi Eric,

Thanks.

I understand that iDirect modem can help to point antenna but too bad that i am using those common modem that cannot do that.

Spectrum Analyzer is a good choice but too Expensive so looking for a alternative cheaper solution.

The main purpose of this equipment is to aid people to point the antenna quickly. Using compass and inclinometer will be too difficult and slow for people.

Best Regards,


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Reply #5 - Jan 8th, 2009 at 4:26pm  
Quote:
i am using those common modem that cannot do that.
For unsophisticated modems and common receivers, an inexpensive L-band signal strength meter may be all you need. See http://www.google.com/products?q=satellite+signal+meter&scoring=p

//greg//
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« Last Edit: Sep 14th, 2015 at 9:57pm by Admin1 »  
 
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Eric Johnston
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Reply #6 - Jan 8th, 2009 at 4:33pm  
What "common modem" do you have that does not have a receive signal quality output ?

Setting the elevation angle accurately using  an inclinometer and then swinging the dish in azimuth is the fastest manual way of finding the satellite.  Just swing the dish sideways once and you find the satellite straight away.

We have a fast automatic system that you stand up on a tripod, power on and the antenna finds the satellite automatically.  It uses GPS to determine its location, flux gate compass, axis encoders and motors.  Works a treat, but costs a fortune.  Similar systems are available for maritime, airborne and land mobile / transportable applications. It is really neat to watch a dish rock steady aimed at the satellite, while the radome roof and deck is moving around as a ship rolls and pitches in heavy seas.

Best regards, Eric
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« Last Edit: Sep 14th, 2015 at 4:51pm by Admin1 »  
 
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USN - Retired
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Reply #7 - Jan 8th, 2009 at 8:49pm  
Eric Johnston wrote on Jan 8th, 2009 at 4:33pm:
It is really neat to watch a dish rock steady aimed at the satellite, while the radome roof and deck is moving around as a ship rolls and pitches in heavy seas.

Been there, done that. With megawatt transmitters no less !! Beacon tracking information get automatically compared with the ships gyro outputs, resulting in real time correction voltages being sent to the antenna pointing servos. Hopefully they're gimballed now, cable wrap was an ongoing issue during my tenure.

//greg//
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« Last Edit: Sep 14th, 2015 at 9:58pm by Admin1 »  
 
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wow
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Reply #8 - Jan 19th, 2009 at 7:42am  
Hi,

>>For unsophisticated modems and common receivers, >>an inexpensive L-band signal strength meter may be >>all you need. See http://www.google.com/products?>>q=satellite+signal+meter&scoring=p

How does these strength meter works? If i want to point to a satellite which i know only its' beacon freq, then can i use this type of meter?

Best Regards,
wow
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Eric Johnston
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Reply #9 - Jan 19th, 2009 at 11:41am  
Cheap satellite meters are like crystal sets with a DC meter on the output. They are simple power meters and measure the composite noise power across the entire L band range 950-2150 MHz (and more!).

If you point the antenna at a satellite with many large high power carriers you will get a big reading.  If you aim the antenna up at the cold clear sky you will get the low reading.  Satellites with few small carriers will give a small reading.  A satellite with beacon only active will not be detectable.

If you are looking for a satellite which as beacon only and no transponder traffic active and pointed down at you, you need a PLL type LNB and spectrum analyser with very narrow resolution bandwidth.

A simple meter will allow you to peak up on all active satellites but will not tell you which satellite is which.  You may find that detecting and peaking up on satellites with only low power carriers is difficult.  The meter needle movement may need a magnifing glass to detect. Considerable skill is needed but it is possible.  Note that simple meters may also detect noise from the sun, ground or your hand.

Best regards, Eric.
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« Last Edit: Jan 19th, 2009 at 4:18pm by Eric Johnston »  
 
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