Astra 2E: Iberia & Balearics Reports

[Nagusia]

I think the easiest way to explain is this. Transmission is at 10GHz. That has a wavelength of 3cm ....

Brilliant explanation and a very satisfying answer to my question. I feel happy to have learnt something new and interesting today. Thanks.

 

[Pride Of Cucamonga]

Yes, error correction is more robust on that transponder (2/3) so can be resolved with lower SNR.

Why do the transponders with a higher symbol rate have a higher FEC?

 

[Tururu]

The supports are aluminum, but a stand of 35-40 millimeters are flexible to the weight of the antenna and a much smoother viewing moves.

A support 60mm or 75mm for that matter are perfect.
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Los soportes no son de aluminio, pero un soporte de 35-40 milimetros son flexibles al peso de la antena y con un viendo suave se mueve mucho.

Un soporte de 60mm o ya puestos de 75mm son perfectos.

PS: Other photos in this post/resto de fotos en enste post.
http://www.satellites.co.uk/forums/threads/gibertini-125-installation.160480/#post-872010

 

[Tururu]

It is very important to know the limits of your signal tuner. What is it?

The other day I watched the minimum signal / SNR of SD channel 28'2 ° East, 12480 tp-DB800S in HD and Vu+DUO², I tried to force below the minimum, I moved the antenna a few degrees.

With DB800S-HD, below 4.0dB, signal / SNR 25% BER poor picture 11,000 every 3 ~ 5 minutes picture/audio.
The Vu + DUO ², signal / SNR% 46% AGC57 good picture during 30 minutes. Without any problem (Twin tuner/dual).

I moved the antenna/degrees and…
With DB800S-HD and 3.5dB signal/SNR 21% BER over 22,000 (highly pixelated),we could say with some picture on black (occasionally), the sound is very bad too.

With Vu+DUO², signal/SNR 32% I was about 20 minutes checking and I notice a poor picture 3 times (the area is marked), the audio without problem, I did not notice anything special during that time

Some images of first tranche.....4.0dB, DB800 signal/SNR 25%.

Some images of second tranche.....Vu signal/SNR 46%.

Some images of third tranche....3.5dB, DB800 signal/SNR 21%.

Some images of third tranche.....Vu signal/SNR 32%.

PS: The threshold is important as seen, Good fishing.

--------------------------
Que umbral de señal/SNR tiene tu sintonizador.? es importante.
El otro dia mire el minimo de señal/SNR de un canal SD en 28'2ºEste, tp 12480 en la DB800S-HD y en Vu+DUO², para forzar por debajo del minimo, movi la antena unos grados.

En DB800S-HD, por debajo de 4.0dB, señal/SNR 25% BER hasta 11.000 pixelando cada 3~5minutos imagen/audio.
El Vu+DUO², señal/SNR 46% AGC57% no pixelo durante 30 minutos que lo deje, ni se entero del problema (tuner Twin/doble).

Baje la señal/movi la antena unos grados y....
En DB800S-HD, con 3.5dB, señal/SNR 21% el BER oscila mucho, por encima de 22.000 muy pixelado, podriamos decir negro con alguna imagen de vez en cuando, el sonido tambien muy tocado.

En Vu+DUO², señal/SNR 32%, durante 20 minutos de prueba, pixelo la imagen 3 veces (la zona esta marcada), el audio sin problemas, no note nada raro durante ese tiempo.

Unas fotos en el primer tramo.....4.0dB, DB800 señal/SNR 25%.
http://imageshack.com/a/img33/8550/hcyq.jpg
Unas fotos en el primer tramo.....Vu señal/SNR 46%.
http://imageshack.com/a/img845/8651/62h5.jpg
Unas fotos en el segundo tramo....3.5dB, DB800 señal/SNR 21%.
http://imageshack.com/a/img138/8265/xx2b.jpg
Unas fotos en el segundo tramo.....Vu señal/SNR 32%.
http://imageshack.com/a/img839/4008/ldvo.jpg
PD: El umbral es importante como vemos, buena pesca.

 

[Huevos]

The Duo has a better tuner than Duo2. And the single tuner is better than the twin at low frequencies and vice versa at the top of the band. And the other weird thing with the twin tuner is blind scan doesn't work on the second tuner even though it seems to scan.

 

[Tururu]

Vu + DUO say nothing, I did not see one for performing the test, if the test could do with DUO2 both single tuner, as a double (4tuner).

Quiet as it does not work the blind search in any of the tuners unfortunately first slot or second slot (single or dual) and dual in any of the 4 tuner present.

I give a really more to blacklist the DUO2 has very high threshold for my taste SR ==> SR 1000, by the upper right hand to SR 44950, a shame not to listen to satellite radio channels with SR more lower than 1000.

PS: Good fishing.
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Del Vu+DUO no digo nada, no vi uno para realizar los test, si pude hacer los test con el DUO2, tanto con sintonizador sencillo, como doble (4tuner).

Tranquilo, ya se que no funciona la busqueda ciega en ninguno de los sintonizadores por desgracia, primer slot o segundo slot (sencillo o dual) y en el dual, en ninguno de los 4 tuner presentes.

Te doy un dato mas para tu lista negra, el DUO2 tiene el umbral del SR muy alto para mi gusto ==> SR 1000, por las parte superior bien hasta SR 44950, una pena no poder escuchar canales de radio por satelite con SR mas bajos de 1000.

PD: Buena pesca.

 

[Huevos]

Why do the transponders with a higher symbol rate have a higher FEC?

There's no connection. It's a matter of choice.

SR is based on spacing between transponders, normally it is about 70% of the step size. In the case of 2E/2F step size is 29.5 MHz and 22 mega symbols. BTW, these band plans are legacy from analogue days so they have just picked the best symbol rate to meet that band plan.

FEC is based on downlink power. When the downlink power is lower you need more robust FEC. If each transponder is 100 watts and you spread that across half a continent, signal on the ground is weak so a robust FEC is needed (pan-European). If you concentrate that same 100 watts on a spot beam, signal on the ground is much higher so less robust FEC is needed (UK spot beam). And somewhere between the two you have have a new semi-spot beam (Astra 2F 12500-12750) that SES have opted for less robust FEC probably also due to very good signal level.

 

[Huevos]

ya se que no funciona la busqueda ciega en ninguno de los sintonizadores por desgracia, primer slot o segundo slot (sencillo o dual) y en el dual, en ninguno de los 4 tuner presentes.

The blindscan works fine. If it doesn't it is a fault with the image/plugin. What image is it?

 

[Pride Of Cucamonga]

There's no connection. It's a matter of choice.

SR is based on spacing between transponders, normally it is about 70% of the step size. In the case of 2E/2F step size is 29.5 MHz and 22 mega symbols. BTW, these band plans are legacy from analogue days so they have just picked the best symbol rate to meet that band plan.

FEC is based on downlink power. When the downlink power is lower you need more robust FEC. If each transponder is 100 watts and you spread that across half a continent, signal on the ground is weak so a robust FEC is needed (pan-European). If you concentrate that same 100 watts on a spot beam, signal on the ground is much higher so less robust FEC is needed (UK spot beam). And somewhere between the two you have have a new semi-spot beam (Astra 2F 12500-12750) that SES have opted for less robust FEC probably also due to very good signal level.

Yes, interesting. Is this actually SES's decision or whomever is leasing the transponder? Noticed that for HD SKy use 8PSK on the UK spots and QPSK on the pan Europeans - is this for the same reason?

 

[Huevos]

Is this actually SES's decision or whomever is leasing the transponder?

You couldn't have broadcasters doing as they please otherwise you would either have co-channel interference or under utilization of bandwidth. Anyway if you look at Astra 1 you'll find as far as these parameters are concerned the two slots are almost a mirror image of one another so obviously SES setting the guidelines.

 

[Pride Of Cucamonga]

You couldn't have broadcasters doing as they please otherwise you would either have co-channel interference or under utilization of bandwidth. Anyway if you look at Astra 1 you'll find as far as these parameters are concerned the two slots are almost a mirror image of one another so obviously SES setting the guidelines.

Looking at AStra 1 then disproves your point that lower FECs are related to beam strength and not to lower symbol rate, as i originally suggested.

 

[Huevos]

Looking at AStra 1 then disproves your point that lower FECs are related to beam strength and not to lower symbol rate, as i originally suggested.

Can you be more specific? Also don't forget the current band plan is legacy from analogue days.

Also I'm not wrong about FEC. Read up on Shannon's Theorum.

http://en.wikipedia.org/wiki/Noisy-channel_coding_theorem
http://en.wikipedia.org/wiki/Shannon–Hartley_theorem
http://en.wikipedia.org/wiki/Nyquist–Shannon_sampling_theorem

Just imagine you are in a noisy bar. Your friend is talking to you but you can't hear everything, so he repeats a few words so you understand the message. That's error correction. The quieter he speaks the more words he'll have to repeat. Same with FEC. Lower power needs more robust FEC. And just like with the conversation the more repeats there are the less time there is for sending new data. Turn up the volume/power and less repeats are necessary.

 

[Pride Of Cucamonga]

OK let's keep it simple and stick to SD transponders on Astra 2....

The old analogue transponders have a symbol rate of 22000 and FEC of 5/6
The wider transponders have a symbol rate of 27500 and FEC of 2/3

You said the lower 5/6 FEC is used on transponders with a stronger UK spot beam, but the same is true with Astra 1 (all beams broadly equal), so this can't be the case. I am wondering why there is a clear correlation between FEC and symbol rate/ bandwidth.

thanks

 

[dxsat]

The supports are aluminum, but a stand of 35-40 millimeters are flexible to the weight of the antenna
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Los soportes no son de aluminio, pero un soporte de 35-40 milimetros son flexibles al peso de la antena y con un viendo suave se mueve mucho.

Your translation should say "The supports are not of aluminium"
la traducción dice el contrario
Saludos

 

[Lazarus]

Mod. Note:

I appreciate that, now 2E is established, the number of reports has dropped off markedly, but there are far too many Off Topic (albeit related) discussions going on here now.

I have, at one Member's request, already invested effort in shifting thirty plus Posts to a separate Topic.

To be obliged to do so again will be tiresome, so will Members please help Staff out by starting their own separate Topics for issues other than Signal Reports?

Thankyou.

 

[Captain Jack]

When you are dead on axis all the signal from satellite arrives at the same time (in phase). But when you are in the first null the path between the feed and the left side of the reflector and down to you is 1.5cm longer than the path from the feed to the right side of the reflector and down to you. This means half the signal arrives completely out of phase with the other half and cancels it out (phase 180º).

This is very interesting. So the cancellation happens when the signal arrives at the dish/LNB, rather than on the way down? I assume, until the cancellation happens, the signal itself is still relatively strong, right? Not understanding much about microwave dynamics, is there a way to stop this from happening - perhaps some sort of phase inverter to "twist" one of the phases back 180 degrees so that cancellation doesn't happen? I guess it would have to be a physical, wave-guide sort of gizmo and not once the signal hits the LNB... as the signal will have been cancelled by then.

 

[Tururu]

Your translation should say "The supports are not of aluminium"
la traducción dice el contrario
Saludos

Gracias por el aviso, es un error de traduccion de San Google, lo siento, no me di cuenta.
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Thanks for the warning, it is an error of translation of San Google, sorry, I did not realize.

 

[Huevos]

This is very interesting. So the cancellation happens when the signal arrives at the dish/LNB, rather than on the way down?

No, it happens as the signal leaves the satellite. It's a feature of a highly focused spot beam. Nothing can be done on the ground to compensate for this. If you wanted to fill all the nulls just defocus the beam a bit, either by not having a parabolic reflector or moving the transmit feed a bit closer or further from the reflector.

 

[Huevos]

OK let's keep it simple

I'd be happy to... but not in this thread.

 

[terryashbyash]

1.1m dish. All transponders remain locked 24 hours.

View attachment 62195

Thanks for the useful info and attachment, just got a replacement 1.1m to replace the old 8ocm(just measured thought it was 85cm) and will have a tweek. Trying times ahead with my old satellite receiver and TV ( better than 10 euro meter from lidl) but hope to get BBC 1+2 HD in time for the return of gardeners and the world cup. Will report when dish fitted and suitably refreshed.