Noise Figure

[rizwan]

How can we know the Noise Figure of any Dish Antenna ?

[filicart]

Re: Noise Figure

explained better! However the signal you can check it with a satellite Finder.
whereas if you have signal and you want to know how strong it is, you can go into the settings of the decoder and see the level of SRC and quality.

[kostis]

Re: Noise Figure

How can we know the Noise Figure of any Dish Antenna ?

Do you mean the db of the lnb? 0.1db 0.2db 0.3db etc?

[filicart]

Re: Noise Figure

right, if you mean the ones, are written on the lnb

[rizwan]

Re: Noise Figure

Try to explain, Every antenna reflecting the signal from sat. also producing some noise or unwanted signals. Written on LNB is noise figure for LNB only not for a Dish antenna

[filicart]

Re: Noise Figure

Try to explain, Every antenna reflecting the signal from sat. also producing some noise or unwanted signals. Written on LNB is noise figure for LNB only not for a Dish antenna

you want to know how to calculate the noise produced by the antenna and not the lnb?

[Mobley3]

Re: Noise Figure

The Dish gain is usually specified by the dish manufacturer, I doubt if it is possible for a person to work out without some serious test equipment. The noise or unwanted signal usually occurs when the LNB is not focused properly in the mount, too far in and you will lose signal as you are not illuminating all of the dish surface, too far out and you suffer from over-spill and therefore noise.

Regards Mobley3

[rizwan]

Re: Noise Figure

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

[Mobley3]

Re: Noise Figure

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

Of course, that is why it is possible to set up Multi-Lnb systems on one dish.
As long as your dish is peaked for a particular satellite and your Lnb is focused properly then there is not a lot more you can do.

Regards Mobley3

[aplok]

Re: Noise Figure

hi,

my dm500 gives the snr (signal noise ratio) of the current channel,
this helps to adjust the dish pointing

i suppose most of sat rcvr gives it too

what rcvr do you have ?

otherwise, the noise figure may also refer to the chain:

[ dish - lnb - contact - cable - contact - rcvr ]

and therefore you should link db loss to each other through db log sum,
according, of course, you've got the db loss of each element of the chain ...

anyway, the snr should cope the job to point the disk to the sat.

[ocram88]

Re: Noise Figure

With a spectrum analyzer you can see all the components of signal and noise arriving at your antenna. Acting on the pointing of the feed can eliminate the noise components.

[filicart]

Re: Noise Figure

but you want to solve that problem?

[kalpikos]

Re: Noise Figure

I found a page where you can calculate the Noise temperature, Noise Figure (NF) and noise factor.

-http://www.satsig.net/noise.htm

[herrr]

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...

[filicart]

Re: Noise Figure

but being a hyperboloid is now standard, it is difficult to improve