Astra 1N - made it to geostationary orbit, now the fun starts

[park_gate]

Do you reckon 2E, F and G will have an even tighter beam than that of 1N, particularly more suited towards the outline of the British Isles from 28.2E? Certainly from the 1N spotbeam footprint it looks similar, if not a bit tighter, than 2D's but the real test is reception reports from various places.?

I believe they will be of a similar design to 1N so no there is no reason to think it will be any tighter. To make it tighter it will need a bigger dish which will put the cost up. Also there would be a risk of problems with reception at the extremes of the UK.

Astra 2D has been good enough for the last 8 years so why go to the extra expense and make it better than 2D?

I have a friend and ex-colleague who is an Engineer working on 2E at Astrium in Portsmouth and he told me he thought it would have a slightly wider beam. He doesn't work on the antennas but said he would check when he got back to the office.

He hasn't got back to me so he has either got it wrong and is embarrassed or has been told he shouldn't give out information like that and has now gone silent on me.

I would expect it to be similar to 2D but we won't know until they are up.

Why are you asking? You shouldn't have any problems in Northern England.


Terry

 

[dvdfilm]

I believe they will be of a similar design to 1N so no there is no reason to think it will be any tighter. To make it tighter it will need a bigger dish which will put the cost up. Also there would be a risk of problems with reception at the extremes of the UK.

Why would it need a bigger dish to make it tighter?How does this thing work?

 

[timo_w2s]

I believe they will be of a similar design to 1N so no there is no reason to think it will be any tighter. To make it tighter it will need a bigger dish which will put the cost up. Also there would be a risk of problems with reception at the extremes of the UK.

I think some may be thinking of that "side lobe" to the south west on the 1N spotbeam which wouldn't be featured on any specific UK spot beams on 2E/F/G as this 1N spot was designed for use in mainland Europe.

 

[Pietclock]

It's the same principle as with your parabolic antenna at home: the bigger the reflector, the higher the gain, the better the focusing, because the opening angle gets smaller.
This is why SES are predicting under 50cm dishes will be sufficient for reception in the UK with the new spot beam - 1N has a very high TWTA output of 130W (2D has only 39W).
If you focus that output very closely you will get a very high EIRP as all the energy is "beamed" to a small area, compared to the pan-European beams.

it will be interesting, if the new 2-series will have such a high TWTA output too, or if the high gain due to the spot beam will be used to lower energy consumption, as the satellites are intended for UK/IRL only.

I guess SES Astra will want them to have pan-European beams too, as they like to shift those birds around in case of problems. See 2C, which again made it back to 19E, probably because old 1H is telling them it's time to step back...

 

[park_gate]

It's the same principle as with your parabolic antenna at home: the bigger the reflector, the higher the gain, the better the focusing, because the opening angle gets smaller.
This is why SES are predicting under 50cm dishes will be sufficient for reception in the UK with the new spot beam - 1N has a very high TWTA output of 130W (2D has only 39W).
If you focus that output very closely you will get a very high EIRP as all the energy is "beamed" to a small area, compared to the pan-European beams.

Do you know the dish size for 2D and 1N?

How do they compare?

Terry

 

[M60]

Are you the M60 from DS forum?

Yep, that's me! I've been having a look on here for a while so thought I'd sign up as generally there's a much better and more clued up community on here than DS!

It's the same principle as with your parabolic antenna at home: the bigger the reflector, the higher the gain, the better the focusing, because the opening angle gets smaller.
This is why SES are predicting under 50cm dishes will be sufficient for reception in the UK with the new spot beam - 1N has a very high TWTA output of 130W (2D has only 39W).
If you focus that output very closely you will get a very high EIRP as all the energy is "beamed" to a small area, compared to the pan-European beams.

it will be interesting, if the new 2-series will have such a high TWTA output too, or if the high gain due to the spot beam will be used to lower energy consumption, as the satellites are intended for UK/IRL only.

I guess SES Astra will want them to have pan-European beams too, as they like to shift those birds around in case of problems. See 2C, which again made it back to 19E, probably because old 1H is telling them it's time to step back...

Whilst 1N is at 28.2E they could reduce the EIRP on the spotbeam transponders too as this will also reduce energy consumption and help reduce overspill in to the continent. I suppose the preliminary footprint is based on coverage modelling and once in use they'll spend a few days tweaking with uplink/downlink power + FEC to see the best combination to keep the footprint as tightly UK focused as they can.

I agree with Analoguesat that the lobe over the west of Portugal won't be there on the series 2's, wouldn't have thought it would appear on 1N's spotbeam either (if it has a seperate spotbeam antenna) but until it's in service and we get updated footprint maps from SES I suppose we'll not know?

 

[Pietclock]

1N has 4 reflectors, 3 are 2.6m in diameter, 1 is 1.3m and steerable.

2D has just 1 reflector, which is 2.03m in diameter
_http://www.boeing.com/defense-space/space/bss/factsheets/376/astra_2d/astra_2d.htmll

and this means 1N should be able to focus much more with its 2.6m reflector. Certainly not good news for fringe reception ! However, the higher TWTA output can widen the beam again.

As far as I know, the TWTAs can be only run at their maximum power, their output cannot be "regulated". This is what I heard from SES in 2003, when the BBC channels went on 2D and SES were asked if they will reduce the output and they answered, that's not possible.

Moderation Note.

Please remember NOT to post live links to outside sites and ESPECIALLY don't embed them. Forum rules.

 

[Pietclock]

I agree with Analoguesat that the lobe over the west of Portugal won't be there on the series 2's, wouldn't have thought it would appear on 1N's spotbeam either (if it has a seperate spotbeam antenna) but until it's in service and we get updated footprint maps from SES I suppose we'll not know?

I guess we wont get any new footprints, as the one published tells everything SES want their costumers to know: only very small dishes needed in Britain, and it's focused. SES do not release real footprints anyway, because that would mean giving the EIRP in dBW and not some strange dish size numbers (which depends on more than just the footprint...)

 

[dvdfilm]

I'm surprised how the tracking sites still have 1N moving nearly a week after it's stopped for testing,usually they correct themselves in a few days

 

[strs65]

I guess most of them get the TLE data from celestrak. And Celestrak doesn't seem to have updated their data about 1N.

Btw, not much activity from 1N today. Is there any test live? I only get a low signal at 12491,V.

 

[dxn]

I agree with Analoguesat that the lobe over the west of Portugal won't be there on the series 2's, wouldn't have thought it would appear on 1N's spotbeam either (if it has a seperate spotbeam antenna) but until it's in service and we get updated footprint maps from SES I suppose we'll not know?

Well I hope the lobe over Portugal still continue on this new bird, I don't wanna loose BBC/ITV channels. Fingers crossed!!

 

[solly]

maybe all testing compelted satellite move to position 28.2e

 

[Llew]

Still in testing mode across the spectrum -

 

[Analoguesat]

1N has 4 reflectors, 3 are 2.6m in diameter, 1 is 1.3m and steerable.

2D has just 1 reflector, which is 2.03m in diameter
_http://www.boeing.com/defense-space/space/bss/factsheets/376/astra_2d/astra_2d.htmll

and this means 1N should be able to focus much more with its 2.6m reflector. Certainly not good news for fringe reception ! However, the higher TWTA output can widen the beam again.

As far as I know, the TWTAs can be only run at their maximum power, their output cannot be "regulated". This is what I heard from SES in 2003, when the BBC channels went on 2D and SES were asked if they will reduce the output and they answered, that's not possible.

A twta is just a bent pipe with some amplification and frequency shifting on it. Hence it just reflects out whats thrown at it. They may run at constant power but the satellite operators can turn down the power going into it - very obvious with the main APTN feed on 10E. The power goes up and down on that one all the time.

 

[solly]

it mean signal strange betwin morning at evening ?>

 

[M60]

It looks like n2yo has finally caught up with 1N, now showing at 1.81E with a Perigee to Apogee difference of only 6.3km.
_http://www.n2yo.com/?s=37775

 

[dvdfilm]

Anyone in Spain using crazyscan and pc tuner card to check signal strength from 1N testing?

 

[Pietclock]

The pattern has changed:

View attachment 43577

Now weak signals in low band, maybe that's the spotbeam now. Comparing results from the UK would be interesting.

 

[Huevos]

The pattern has changed

What aerial are you using to monitor 2ºE?

 

[strs65]

Nothing here today...




@Pietclock
What's your DVB card?