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Geo Coordinates of iDirect Remote Terminal

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martin.amara
Ex Member


Apr 29th, 2013 at 12:57pm  
Dear Mr. Eric

Kindly explain how much variation in Geo coordinates of a remote site  is acceptable in iDirect VSAT system or any other VSAT system. Also let me know if this is same in all cases independent of hardware manufacturer.

Martin
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SuperDave
Ex Member


Reply #1 - May 1st, 2013 at 2:31pm  
Martin,
While you want to get your remote Geos as accurate as possible, the short answer is that iDirect nodes  (and other brands) will still work even if your Geos are several hundred meters off (as the Hub will allow some tolerance by adjusting symbol offset) BUT there is a caveat... The best way I can explain it is that Your Geos are serving as a time calculation based on distance, so as long as the distance between the bird and your remote remains the same as what your Geos represent, you wont see issues. Imagine holding a 8 inch long string at 6 inches away from a basketball, you can pull it tight and make a sweeping arc across the surface of the ball. The string length (i.e. distance… i.e. time) from your hand (Satellite) to the ball (earth) remains constant but the "Geos" on that basketball vary greatly. In earth terms that arc could in theory cover couple hundred kilometers from the actual Geo coordinates of your remote yet still be the same distance (time) from the satellite. (sorry it’s the best illustration I could think up at the moment)
If you suspect one of your iDirect remotes has bad Geos you can compare the Symbol-Offset to other remotes in the inroute, you find one showing a Symbol-Offset several hundred points different that the others, Id first plot it on Google earth and verify Geos with the Opt file, then dispatch a tech with a GPS and be sure that both the NOC and the tech are both clearly using either D:M:S OR Decimal (and not mixing the two formats!)
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fluffymassive
Ex Member


Reply #2 - Jul 8th, 2013 at 5:37am  
Quote:
Martin,
While you want to get your remote Geos as accurate as possible, the short answer is that iDirect nodes  (and other brands) will still work even if your Geos are several hundred meters off (as the Hub will allow some tolerance by adjusting symbol offset) BUT there is a caveat... The best way I can explain it is that Your Geos are serving as a time calculation based on distance, so as long as the distance between the bird and your remote remains the same as what your Geos represent, you wont see issues. Imagine holding a 8 inch long string at 6 inches away from a basketball, you can pull it tight and make a sweeping arc across the surface of the ball. The string length (i.e. distance… i.e. time) from your hand (Satellite) to the ball (earth) remains constant but the "Geos" on that basketball vary greatly. In earth terms that arc could in theory cover couple hundred kilometers from the actual Geo coordinates of your remote yet still be the same distance (time) from the satellite. (sorry it’s the best illustration I could think up at the moment)
If you suspect one of your iDirect remotes has bad Geos you can compare the Symbol-Offset to other remotes in the inroute, you find one showing a Symbol-Offset several hundred points different that the others, Id first plot it on Google earth and verify Geos with the Opt file, then dispatch a tech with a GPS and be sure that both the NOC and the tech are both clearly using either D:M:S OR Decimal (and not mixing the two formats!)



excellent explanation! Smiley
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