Communication confusion in the satellites!!!

Why uplink and downlink frequencies differ in satellite communication?

Maybe the frequency variations depend on the energy from the transmitter and receiver...

May be your right but not exactly.....

This ambiguity lies in the power budget of the corresponding systems and atmospheric effects have also impact it.

We know from the plank's law of radiation that the energy of a particular wave is directly proportional to its frequency.

But microwave frequencies have a severe effect with the increased frequency, i.e more attenuation occurs by interacting with the external bodies(ex. Microwave oven 2.45Ghz).
In satellite communication uplink refers to the link from the ground communication equipment to the satellite. Typically it's of 16Ghz in the C band.

This is why because if the uplink frequency is less, due to its less energy it gets reflected back by the Ionosphere. If the energy is more (i.e high frequency). It can run through the ionosphere And reaches the satellite.

From the satellite perspective, power budgeting is quite essential, to sustain the communication link with the ground station, and its main power source is the sun. Thus the transmitted frequency by the satellite is nominally is less than that of the ground sending signal.

That's the reason why uplink frequencies and downlink frequencies are different...

More likely to say downlink frequencies are less, in comparison with the uplink frequencies.

Olbers paradox

    Why is it dark at night?

It's a silly question. As the sun is absence it appears dark.

But it not right.....

In the morning sunlight scatters the atmosphere. So, it appears blue. If there is no atmosphere like on the moon, it appears dark, even the sun shines.

So, why the space dark?

It's full of stars, galaxies. No matter what direction you picked, you will find a star or galaxy. But actually, space is not dark...
But why it appears to be dark at night?
Hubble space telescope-HST took the images of the universe with an infrared camera.

Why??

Because distant stars and galaxies are moving away from us causing frequency shift more and more(due to expansion of the universe), the Doppler effect causes redder which are moving away from us, and it goes on to infrared. Thus we cant see them.
German astronomer "Heinrich Wilhelm older" made an incredible paradox widely known as the "dark night sky paradox".

This specifies two issues about darkness.

1. The universe is expanding.
So, light from the distant stars is 'red-shifted' to obscurity.

2. The universe is young.
Light from distant stars hasn't even reached us yet.

This is the reason behind the dark in the night.

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