Sir,

Just want want to know, how is it possible that there are two or more satellite that marked on the same orbital position like Astra 1 A ,Astra 1 B , C and D @ 19° E?

Regards,

ken

Same satellite. The different letters designate coverage areas. The info I have however, now indicates the designations are
Astra 1H: https://www.ses-astra.com/business/en/support/media-library/Footprint-Graphics/Footprint-Graphics-19-2-East/astra-1H.php
Astra 1KR: https://www.ses-astra.com/business/en/support/media-library/Footprint-Graphics/Footprint-Graphics-19-2-East/astra-1KR.php
Astra 1L: https://www.ses-astra.com/business/en/support/media-library/Footprint-Graphics/Footprint-Graphics-19-2-East/astra-1L-FSS.php
Astra 1M: https://www.ses-astra.com/business/en/support/media-library/Footprint-Graphics/Footprint-Graphics-19-2-East/astra-1M-Widebeam.php

//greg//

thankyou sir,

but how about the ABS 1, 1A and 1B do they are the same satellite also?

ken

Not much consistency in the way the owners designate their satellites. In this case they're three different satellites: see https://www.absatellite.net/  To confuse matters even more, ABS 1B appears to the same satellite as Eutelsat W75 - which used to be called EuroBird 4 - which is not to be confused with EuroBird 4A.

Another confusing method is to add a suffix when a satellite is replaced at a particular longitude. Galaxy 3 is a good example. G3 failed some years back, and was replaced on-orbit by G3R (the "R" apparently representing "replacement")

//greg//

Thankyou sir, now I know.

One more thing sir how do it became possible that the 3 satellites of ABS are in the same orbital position 75 E?
And they are planning to add 1 according to their site.

regards,

ken

Multiple satellites are put in close orbit proximity so that small dish antennas can see all of them in the broad beam of a small dish. For satellite TV service, each satellite will operate in different parts of the frequency band.

The satellites do not have identical orbit parameters as then would then be collided. The are positioned very slightly apart, but not so far apart that small dishes can't see all simultaneously.  For the large dish teleport uplinks separate large dishes are needed to track each individual satellite.  The teleports can tell which satellite is which by different telemetry beacon frequncies.

When old satellites are replaced it is normal to co-locate the new satellite and then progressively switch off individual transponders on the old satellite and switch on transponders in the new satellite.  Rearrangement of carrier frequencies will also be done so as to make use of the additional capacity of the new satellite which will probably have more spot beams, different coverage etc.

Best regards, Eric.  

ok sir eric and sir greg,

I understand it now more clearly.