Astra 2F at 28.2E: General Discussion

[Lazarus]

I'm shattered

The Spanish Talk Radio Expert said 16th December almost certain !!!

Yes, but that's migration from 2B to 2F - nothing to do with next years move from 1N to 2E.

ie BBC is "safe" for a good few months yet.

 

[C0re]

Let the speculation begin when the migration of the 2B (and possibly 2A) to the 2F will take place ;)

 

[Mr Hoover]

Yes, but that's migration from 2B to 2F - nothing to do with next years move from 1N to 2E.

ie BBC is "safe" for a good few months yet.

From what I remember about the talk yesterday was that he was on about "the free channels" going around then...according to his "Spies"...

 

[Analoguesat]

BBC will move off 1N in the second half of 2013

www.bbc.co.uk/blogs/aboutthebbc/posts/Changes-to-BBC-Satellite-transponders-in-2013

and this confirms they will be on 2E

 

[BlindFaith]

Does anyone use 1/1?

Yes, but not for satellite ;) DVB-S (2) hast always a 2 step error correction mechanism (outer and inner coding). Cable (DVB-C) only uses a single step.

 

[Redjenko]

So ...in lay mans terms ....does this mean that if I have lost the channels that have already moved , its safe to assume I will lose the BBC and whatever else moves once 2e is operational , as they are the same footprint ?

 

[Analoguesat]

So ...in lay mans terms ....does this mean that if I have lost the channels that have already moved , its safe to assume I will lose the BBC and whatever else moves once 2e is operational , as they are the same footprint ?

The 2E footprint will be broadly similar

 

[DishDick]

I am sure the footprint will be similar, but I am also sure there will be 7 months of speculation. May I start - I hear the someone on a boat in the English channel 1 meter from the UK coast wil need a 3 meter dish for BBC

 

[M60]

At least that puts speculation to bed, guess the 2A or 2B transition to 2F will now take place after Christmas. I assume 2G will eventually cover all of Bands C and D too so as to offer full redundancy to 2E and 2F. I presume therefore 2D is still hanging around as a current backup to 1N (and later next year 2E's) Band D TP's, with it not in use and housekeeping kept to a minimum it will save the craft fuel.

 

[Juan69]

Did your re-alignment include optimising the LNB Skew?

Tivu yes thank you. Seven o´clock seems to be right for me. Moving it at all either way from seven and things get worse; but there has definately been a change in the CH 5 cluster. Increased pixelation which makes it hard to watch.

 

[Lazarus]

Tivu yes thank you. Seven o´clock seems to be right for me. Moving it at all either way from seven and things get worse; but there has definately been a change in the CH 5 cluster. Increased pixelation which makes it hard to watch.

Yes, there's no surprise you have found issues with the Ch5s ............... but my concern was why your tweaking adversely affected BBC.

 

[Huevos]

1/1 (ie non),

No such thing as 1/1 for DVB-S signals and if there were it would be 50% signal and 50% correction, i.e. a very easy signal to receive.

As far as error correction goes these are SES standards on the Astra satellites. 5/6 for DVB-S in low band and 2/3 in high band. And for DVB-S2 2/3 for 8PSK and 3/4 for QPSK. Obviously there are exceptions but if you look across the board this is what you will find. And the truth is if anything there is probably going to be a drive to smaller dishes in all areas, which after all, as most satellite enthusiasts know, is every housewife's dream.

 

[Huevos]

BBC is "safe" for a good few months yet.

Well British TV is a safe bet already for anyone receiving from 2F because it is already carrying 4 of the 5 major channels. And 2E just increases the chances for anyone who has been unlucky with 2F.

 

[M60]

No such thing as 1/1 for DVB-S signals and if there were it would be 50% signal and 50% correction, i.e. a very easy signal to receive.

As far as error correction goes these are SES standards on the Astra satellites. 5/6 for DVB-S in low band and 2/3 in high band. And for DVB-S2 2/3 for 8PSK and 3/4 for QPSK. Obviously there are exceptions but if you look across the board this is what you will find. And the truth is if anything there is probably going to be a drive to smaller dishes in all areas, which after all, as most satellite enthusiasts know, is every housewife's dream.

I thought 1/2 was 50% correction, 50% available symbols? Your right that most use 5/6 for low band and 2/3 in high band, guess though that SES may relax this considering the new birds have higher EiRP levels giving C/N figures much better than previous, certainly the case with the PE beam's for the new birds which will have a much noticeable improvement over 2A and 2B.

I suppose at the end of the day SES want to maximise revenue, broadcasters though will want to push FEC as far as possible to maximise available bandwidth, certainly where DVB-S2 is concerned for people like the BBC who are keen to keep distribution costs down.

I notice at 13E there's some very high Symbol rates and lower FEC figures, giving something like up to 60MB available baseband bandwidth.

 

[Huevos]

No 1/2 is 33% correction. 1 part correction and 2 parts data is 3 parts. 100% divided into 3 parts is 33%.

If you go back through the BBC Blog they tell you that they consulted SES to maximise the data throughput on the BBC HD transponder and 8PSK and 2/3 was the recommendation. In this relationship the BBC is always going to listen to SES, and SES is always going to err on the side of caution. Neither want customers to lose service by playing with the FEC, and like I said earlier power = smaller dishes, it's not for higher throughput.

I thought 1/2 was 50% correction, 50% available symbols?

 

[satelliteman]

1/2 FEC means half the data is error correction. A higher FEC of 7/8 means 1/8 of data is error correction.


Source: Domestic Radio TV & Satellite Reception - Confederation of aerial industries by RA Calaz, MIEE, MSCTEE, ACGI 2002
An FEC of 2/3 equates to two thirds of the signal being data and one for error correction.



Source: wikipedia
3/4 FEC, for every 3 bits of data, you are sending out 4 bits, one of which is for error correction.


Source: Introduction to digital modulation -catv
An FEC system denoted as 3/4 implies that one extra Error Correction Bit is transmitted for every 3 data Bits. Similarly for a
<div>7/8 FEC, one Error Correction Bit is transmitted extra for every 7 Bits of data. As one can imagine, an FEC of
3/4 provides better correction and is less prone to error and noise than an FEC of 7/8. To that extent, an FEC
of 1/2 would be extremely robust since it would carry one correction Bit for every data Bit.

</div>

 

[Juan69]

Yes, there's no surprise you have found issues with the Ch5s ............... but my concern was why your tweaking adversely affected BBC.

I am not sure I understand the question. The dish is tuned so that all channels are clearly received and viewed, except for the 5 cluster which breaks up with only around 35% quality. When I tweek to try and improve from 35% I start to loose quality on all others.

 

[joddle]

I am not sure I understand the question. The dish is tuned so that all channels are clearly received and viewed, except for the 5 cluster which breaks up with only around 35% quality. When I tweek to try and improve from 35% I start to loose quality on all others.

But is that surprising? - if the skew is set properly for 28.2E then it makes sense that changing it will worsen the signals - if you say the set up was good then the 5 cluster is not weaker because the skew is wrong but because the signal is not as good - or have I missed the point? SQ is very dependent on the correct skew

 

[BlindFaith]

1/2 FEC means half the data is error correction. A higher FEC of 7/8 means 1/8 of data is error correction.

True FEC also called code rate is the inner coding (convolutional). But there's more redundancy. The outer coding (Reed Solomon) uses 204 byte for each 188 byte ts_packet.
A DVB-S symbol rate of 22MS/s and FEC of 5/6 resulting in a brutto bit rate of 22*2=44Mbit/s with a net bit rate of 44*(188/204)*(5/6)=33,79 Mbit/s

 

[satesco]

A new frequency at 28.2 E.Still not sure, but I don't think it's on Astra 1N,but on 2F pan-european beam.The signal is very strong at 16.6 dB,and it has a symbol rate of only 800 Ks?