Noise Figure

[nml52]

Re: Noise Figure

The only way to get the results you want are with a good satellite meter, most problems are caused by bad alignment, including noise.

Hope this helps nml

[aplok]

Re: Noise Figure

You are right, but it also produce due to other satellites signal too

so, if we have a dish pointing to azi0, elev0,

the reflection is given as

__http://en.wikipedia.org/wiki/File:Sidelobes_en.svg

the problem is to estimate the reflection (~interference) of this dish, spotted by sat0, sat1, sat2, ...,

that is to superpose, sum db log of each individual sati response

now if we are concerned only by astra (sat0), your problem shoudl be to estimate

sum response sat1 2 3 ..

to estimate the 'noise' of the dish from other sat1 2 3 ... and local interference sources but not sat0

[rizwan]

Re: Noise Figure

I have still serious difficulties to understand: what you ask it's a technical figure typical of active devices, such as amplifiers or converters.
LNB is a converter and it's very important its SNR: in 30 years of satellites it improved so good that now we can use very smaller dishes.
About the dish itself I've never heard talking about SNR, what's interesting it's its gain...

Its difficult for you, may be you mostly use small Antennas Or Branded type. We use mostly in our Country slightly Large and some time Big, I also own 12 feet Dish Antenna, which is locally manufactured , When Big Antenna give you more gain, it also have more noise too

[BlueIsMyColor]

Re: Noise Figure

You can read something about this in this page:

_http://repairfaq.cis.upenn.edu/sam/icets/satellte.htm

The lower the noise factor, the better the picture quality. For good reception and image results, the quality of the LNC (LNB) and the satellite tuner are of vital importance.

regards

[ocram88]

Re: Noise Figure

But you want to eliminate the noise components from earth, air and signal or interference domestic?

[aplok]

Re: Noise Figure

hi,

as the dish are, like rizwan said before, locally made, home made, or even prototype,

it is an idea to shape it one way of another to reduce impact of other emg sources,
as gsm source, reflecting building, ...
at case-by-case level, ie at in-situ

he said the dish are pretty large, so some 'hole' in the dish may help those local interferences source ...

and consequently noise from interference with them

why not ? an idea to test !

( pleased to hear from your experiments ... thx)

[rizwan]

Re: Noise Figure

This Dish have Quite good result, but I think, it need more improvement, which is only possible, when I know where is the problem

[herrr]

Re: Noise Figure

When Big Antenna give you more gain, it also have more noise too

At last I've understood: what you say is not true, but helps me to understand what you mean.
I said it's not true, because bigger dishes involve both better gain and less noise...
but you mean, I think, big but not perfect dishes.
So I think the problem is irregular dish reflection and not "noise", and it's quite difficult to fix it...

[gianni253]

Re: Noise Figure

Noise is mainly originated by active components, such as LNB, not by dish.
Bigger dish will result in higher gain and better (higher) SNR (signal to noise ratio)

[ocram88]

Re: Noise Figure

Are there filters that are able to eliminate you the spurious components?

[herrr]

Re: Noise Figure

Are there filters that are able to eliminate you the spurious components?

No, if you mean electronic filters, yes, if you mean LNB with a grounded grid that helps to prevent interferences, but the best is try to move dish in a protected location.

Anyway, I think we're talking about different things, from original question of rizwan...

[fandm]

Re: Noise Figure

I would say all this has be discussed before.
Take your box and a small tv to the sat box unless it is in such a position that makes it impossible.and watch the signal meter on the sat channel bend or shape your dish and twist the lnb to the best signal and quality.
No one gets 100% signal you may get it with the quality scale.
Perfection is impossible.