Team,
Can someone help me understand satellite location discrepancies?
I'm trying to put together a list of satellite names, locations, programming, etc.
But I seems some satellites are located behind other satellites or some satellites share the same location.
Are the satellites not in a ark located one after another numbered in sequence?
Please advise.
well, Noah put them in the ark by pairs, one male, one female, to ensure the future of FTA.
Ok, jokes aside, satellites have an orbital slot, but can share that slot with other satellites, they are actually kept at some distance from eachother, but close enough that when seen from here (some 30000km away), it appears they are in the same slot and can be received simultaneously.
That's the case with most slots actually, and in Europe, some orbital positions like 19.2 East and 26 East have up to 5 active satellites in the same slot, and possibly some spares (kept in position but not broadcasting).
Closer to us, 119W has 3 satellites, 30W has 2 (and had 3 during the transition from Hispasat 30W4 to Hispasat 30W6), 95W has 3 satellites but only 1 that covers North America, etc. They just have to be managed carefully so that they don't colide, and the frequencies also have to be managed so that they don't overlap. In many cases, when the colocation was planned during construction, the frequency plan for each bird is made so that they can't overlap.
one more thing, when the satellites get old, or after a defect, they start running out of the fuel that they use to stay in position. A common practice is to then use what's left only to keep the longitude position (the orbital slot) and they start drifting north/south, in an inclined orbit. From our location, it looks like they move up and down throughout the day. Those are then rarely used for TV transmissions.
I hope this helps answer your questions
