SES and ITV testing new FEC settings

[timo_w2s]

Id love to know what the ACTUAL dBW levels are now - from the signals Im getting here on the UK spots Id guess it was nearer 60.

Yeah, I would say so too. I've seen footprints on other sites suggest 2F's European beam is 57dBW over central UK and 55dBW over the far north of Scotland and as we know the UK beam seems even stronger.

 

[Analoguesat]

Over the summer I shall have a go with getting signals off just an lnb & pictures from reflections off a saucepan lid

 

[Archive4]

Over the summer I shall have a go with getting signals off just an lnb & pictures from reflections off a saucepan lid

I think that's called " extracting the urine "

 

[timo_w2s]

I don't know where this was originally from but I've had this chart on my hard drive for some time and is useful as a quick reference as to approximately how much signal I need to lock something. I don't quite understand the minus dB for some DVB-S2 QPSK FECs though.

 

[hvdh]

Negative dB values are perfectly possible.
Comparing two values within the same unit is often done in dB's.
3 dB: carrier power is twice the noise power.
-3 dB: carrier power is half the noise power.
The DVB-S/S2 table (common ones only), sorted on the threshold dB's:

 

[Huevos]

I don't quite understand the minus dB for some DVB-S2 QPSK FECs though.

0dB would be the noise floor. So according to your chart using those extremely forgiving FEC values, it would be possible to extract a signal that is below the noise floor.

 

[Huevos]

No longer receiving 11053H on a 1.1m dish (with the change to 5/6). 1.8m is plenty. If S2 transponders got to this level there are going to be a lot of unhappy people right across Europe.

 

[Huevos]

Graph shows signal hovering around the 9.5db theoretical receive limit for 8PSK, 5/6.

 

[timo_w2s]

0dB would be the noise floor. So according to your chart using those extremely forgiving FEC values, it would be possible to extract a signal that is below the noise floor.

Would be interesting to see a transmission like that, although I assume it would be horribly inefficient bandwidth wise and pointless to use for a DTH satellite service.

 

[Fisty McB]

This is a data rate table I've calculated using a SR of 23000 with 8PSK modulation using DVB-S2, it doesn't take into account roll-offs but it does take the FEC as a variable, with pilots on and off...

DVB-S2 --::-- S/R: 23000 --::-- Mod: 8PSK

FEC    | Pilot Mbit/s    | N/Pilot Mbit/s|
-----------------------------------------
3/5    | 39.89        | 40.94        |
-----------------------------------------
2/3    | 44.39        | 45.55        |
-----------------------------------------
3/4    | 49.93        | 51.25        |
-----------------------------------------
5/6    | 55.55        | 57.01        |
-----------------------------------------
8/9    | 59.30        | 60.86        |
-----------------------------------------
9/10    | 60.04        | 61.62        |
-----------------------------------------

(If you have trouble reading the above table, copy & paste it into Notepad or a similar program.)

It shows that going from an FEC of 2/3 to 3/4 gives roughly a higher data rate of around 5.5 Mbit/s while going from 2/3 to 5/6 nets a higher data rate of around 11 to 11.5 Mibt/s.
I'm assuming that if they're testing an FEC of 5/6 then the 3/4 tests must have worked as expected. They could in theory even go to 8/9 or 9/10, through the jump between them yields only a very small increase.

On my Vu+ Duo2, the tuner only reads as high as 14.9 db for the SNR, but both test transponders do go at least that high.

 

[Fisty McB]

Would be interesting to see a transmission like that, although I assume it would be horribly inefficient bandwidth wise and pointless to use for a DTH satellite service.

I'd imagine it might be used in locations where bandwidth itself isn't a problem but the receiving SNR might be, either through weak transmission power, restrictions on dish sizes or where reception is targeted at areas with regular heavy rain fade.

I'd sayif Sky could use such FEC values of 1/4 or 1/3, the size of dishes needed could be very tiny indeed (allowing for beamwidth interference).

 

[Huevos]

where reception is targeted at areas with regular heavy rain fade.

Like the UK?

 

[Archive4]

Did some tests this morning using the 1.8, bent 1.37 and the LH110

No problem with 1.8, 11053 H at 11.8dB, 11464H at 12.9. Neither the LH110 or the bent 1.37 can see 11053 H fec 5/6, both smaller dishes see 11464 H at 10dB, with 10847 V ( BBC1 HD ) at 8.9. Need to order, or find locally, ie next door, a 1.37 that is working correctly to see if than can see 11053. Have the keys to next door but one, but the cable run will be about 85m so not sure if that is a fair comparison

 

[Nagusia]

No 11053 H for me today - it's raining. 8.5 dB SNR doesn't seem to be enough for a lock.

 

[Archive4]

No 11053 H for me today - it's raining. 8.5 dB SNR doesn't seem to be enough for a lock.

Not surprised, all calculations by various experts all seem to concur that for fec 5/6 9.5 dB is theoretical minimum

My system cannot even see it, unless I use the 1.8

 

[Tururu]

The weather worsened since a couple of days ago, the tuner lost the signal in 11053, says he finds nothing, however I BER, staring spectrum analyzer tp 11053 has good sign, I remember earlier levels with spectrum analyzer .

El tiempo empeoro desde hace un par de dias, el sintonizador perdio la señal en 11053, dice no encuentra nada, sin embargo tengo BER, mirando con el analizador de espectro el tp 11053 tiene buena señal, no recuerdo niveles anteriores con el analizador de espectro.

Previous levels/Niveles anteriores.
11052H = 9.00dB SNR56% AGC99% BER 0

 

[lovelyperson]

.........

My system cannot even see it, unless I use the 1.8

Alicante.....light rain but 1.8m needed.

Look at the .db of those data transponders!

 

[4wd]

11053H strong signal at some periods in the day, but struggling hard to lock.

 

[Analoguesat]

Alicante.....light rain but 1.8m needed.

Look at the .db of those data transponders!

View attachment 73395

I think those data channels are on Astra 2C

 

[timo_w2s]

I think those data channels are on Astra 2C

Yes, they are. They hit 20dB (max level) on my DrHD F15 on a 1.8m in Helsinki.