Why uplink and downlink frequency of a satellite are different ??

[Sankalp Anand]

Lets first define these terms.

Uplink frequency is the frequency at which an earth station sends data
to a satellite in space while the Downlink frequency is the frequency
at which a satellite sends signals back to any earth station.

These two terms you must have came across while doing some settings
job of TATA SKY or DISH TV Set Top Boxes.

For the Electronics guys, this forms to be a part of their curriculum.

The main reason for keeping these frequencies apart is to avoid
interference between the upcoming and outgoing signals since they
received and sent from a single body that is our satellite.

There are several other remedies indeed.
They are
1)Distance:To prevent interference you can move the transmitters far
away from the receivers.
2) Power:You can decrease the power of the transmitters and decrease
the receive sensitivity of the receivers.
3) Directivity:Use very directional antennas that don't have high
emissions.
4) Barrier: Man made or natural barriers such as walls, mountains,
trees, metal buildings, etc block unwanted signals.
5). Frequency: Use separate frequencies that are far enough in range
from each other to eliminate interference.

Out of these reasons, only the fifth one proves to be the most
feasible solution to keep the two data streams undisturbed given that
the size of a satellite is limited.


Please Keep Posting...

Regards
Sankalp Anand