Satellite Communications/SATCOM


QUESTION: Sir, my question is:
A Satellite is placed in a synchronous orbit around the planet Venus. It is required to transmit monochrome pictures of the planet with a resolution of 600 x 400 pixels when Venus is closest to earth. The satellite onboard power is 312 W. About 60% of this power is used for transmission of signals. The antenna used onboard has 3m dia. The signal is transmitted in X band and received on the ground with a dish antenna with 30 m dia. The noise temperature of the earth station is 20K. Find the maximum data rate that can be transmitted through this link and the time taken for transmission of on picure.

Plz reply asap.

ANSWER: Hi Mr Vatsal,
Your question has some major mistakes: A satellite that is synchronous with Venus
will be an orbiting satellite to Earth irrespective of whether Venus is near or not.
Then the video or images it can take of Venus happen to be the same spot all the days
and nights of Venus and no new information will be available.
If this is understood then monochrome or colour or any such thing does not matter!!!
Hope you understand the Satellite Orbits and communication Systems together.

---------- FOLLOW-UP ----------

QUESTION: Sir, This question is asked in our college exam and not able to give this answer.
So, if there is no new information available then data rate will be 0,is it so? and the time taked for transmission of on picture - how to find this one. ?

Hi Mr Vatsal,
I am sorry to inform that the question itself is wrongly framed, may be by mistake in your EXAM. Or else there may be some typing errors. Satellite Linkk Equations do not give such solutions even to deep space missions and if it is a joke that a satellite is placed in synchronous orbit around Venus looks funny to me. You may contact your Teacher Sir for clarification: I also teach that subject to my students but never ask this type of crazy problems. If the test is to be done on Link Budget formulas then a parameter called "MODULATION" also has to be included in the data to complete the calculations and that is how we do as consultants. Just consult your teacher is my advise, he may give you some solution and note that I am not endorsing your conclusive results.

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Satellite Communications Applications, Link Calculations, Teleports, Earth Stations,VSAT, Tracking, Mobile Communications, Next Generation Networks.


40 Years. Indian Space Research Organisation, PANAMSAT, Satellite Based VSAT Networks, IP Networks.

ISRO, PANAMSAT, Engineering Institution for Higher Education (GVP College of Engineering), Consultancy.

Graduate in Electronics and Communication Engineering with Distinction. Guiding scholars for their Doctoral thesis in related areas in Academics.

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