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Thread: How does an antenna communicate with a satellite?

  1. #1 How does an antenna communicate with a satellite? 
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    Need to find out for a project i am doing, the satellite in question is in geo-stationary orbit if that helps.


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    The orbit that a satellite takes has no effect on how an antenna connects to it just to let u know. Basically the antenna transmits binary code in the form of infrared waves. I can explain more if u would like.


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    That's our Man of Science. Often in error, never in doubt.

    Try these web pages.
    http://en.wikipedia.org/wiki/Communications_satellite
    http://en.wikipedia.org/wiki/Microwave_radio_relay
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    Well thats a little harsh don't u think? Besides Harold I am almost never wrong. Microwaves are within the infrared spectrum and therefore I am correct. There are also different relays for different KINDS of satellites but not for different types of ORBITS. Some use radio waves, some use microwaves, and some use tv waves.
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    Quote Originally Posted by the man of science
    well thats a little harsh don't u think harold?

    Quote Originally Posted by the man of science
    Basically the antenna transmits binary code in the form of infrared waves.
    Infra red waves? It's 100% wrong. And you were 100% confident, so although harsh, it also seems to be accurate. (I'm also doubtful that all transmissions are digital.)
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    I never said that it was all digital. I am not wrong. I said that infrared and microwaves are in the same spectrum. Infrared is on the visual spectrum and microwaves aren't. Look at it this way: u can't send info in a visual wave form like ultraviolet or infrared. I did not know that they were transmitted within microwaves. I knew about radio and tv but not microwaves. I know that all aforementioned waves are within the infrared spectrum so I said that to identify them.

    One last thing.

    microwaves=infrared waves in terms of frequency etc.
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    I rest my case.
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    Quote Originally Posted by the man of science
    I am not wrong. I said that infrared and microwaves are in the same spectrum. Infrared is on the visual spectrum and microwaves aren't. Look at it this way: u can't send info in a visual wave form like ultraviolet or infrared. I did not know that they were transmitted within microwaves. I knew about radio and tv but not microwaves. I know that all aforementioned waves are within the infrared spectrum so I said that to identify them.

    One last thing.

    microwaves=infrared waves in terms of frequency etc.
    I'm sorry man of science, I really don't want to be critical, but you are posting inaccurately and casual readers may pick up what you post as being correct. For example, some errors from your last post.
    1. Infrared and microwaves are on the same spectrum, as are gamma rays and radio waves and X-rays and light, etc. But they are on quite different parts of the spectrum.
    2. Infrared is not on the visual spectrum. That's why it's called infra-red.
    3. Equally ultraviolet is not on the visual spectrum.
    4. The 'aforementioned waves', are not part of the infrared spectrum.
    5. There is no such thing as TV waves.

    I worry that these comments may discourage you from posting and that is the reverse of what I want to do. I would like you to post more, I just think it would be helpful if you would take a little more care to check your facts.

    This wikipedia article may help:http://en.wikipedia.org/wiki/Electromagnetic_radiation
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    No u don't. I justified my answer and it is correct. I read ur wikipedia articles and they affirmed what I said. If u r as ur picture suggests, an elderly man, then u should be beyond insulting and criticizing younger men who are CORRECT. If I was wrong then fine I admit it. But I wasn't and u have no right to insult me like that. Reread my posts. 9 times out of 10 I am right on the money.
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    Elderly?! I resemble that remark.
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    R u sure u didn't mean resent? Look I respect u as a fellow intellectual and I think u should do the same for me. If I am wrong tell my WHY I am wrong or where I am. I have no problem with that. But if u insult me and/or question my intelligence then that bothers me.
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    Quote Originally Posted by the man of science
    R u sure u didn't mean resent? .
    The comment "I resemble that remark" is an old joke (told by old men :wink: ). I think Harold was trying to lighten the tone of the exchange.

    Please note that I have pointed out in some detail where you have been in error in this thread. This is not in order to insult, but in order to clarify for everyone. If you think any of my corrections are themselves in error, then please point them out.
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  14. #13  
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    Quote Originally Posted by John Galt
    The comment "I resemble that remark" is an old joke (told by old men :wink: )
    Old enough to remember Curly, of the Three Stooges. Nyuk, nyuk.
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    such a good show!!!
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  16. #15  
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    Snooty Rich Lady: "Murphy, who are those slovenly creatures at the door?"

    Murphy the butler: The plumbers, Madam.

    Snooty Rich Lady: Well, send them to the servant's entrance. We can't allow rifraff in the front door.

    Curly: I Resemble That Remark !
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    Thank you for the help so far... please could you go more in depth for me?

    Thank you
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    a fellow intellectual
    ROFL maybe if we all lost a hundred IQ points.
    everything is mathematical.
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    I have an iq of 140 organic god. So unless u consider 240 to be the normal iq I suggest u shut up. By tv waves I guess I meant long electrical oscillations. Either way I see where I made my error. The following is my revised answer:
    Information is transmitted in binary code within microwaves or radio waves. The orbit of the satellite makes no difference as to the way an antenna communicates with a satellite.
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    Ok, so how does the antenna produce these binary codes that are emitted within microvaves etc?
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    well binary code( at least as far as modern day) is created by a computer. The satellite reads binary code and from this info changes orbit, etc.
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    Man of Science, I have spent my life in electronic engineering, I have worked at Jodrell bank, for NASA (sub contract) for the European Space Agency on several satellites, I have also worked for IBM. There is a very small part of the Space Shuttle system that is my design as well. Pretty much all your replies are misleading to say the least. Your last reply in which you equate 'long electrical oscillations' with 'microwaves' is a contradiction. I suggest your IQ is probably closer to your blood pressure.... :wink:
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    That was mean and totally unnecessary. My uncle works on the Polaris program so there is my basis. If you claim I am so unintelligent then why don't you test me. Prove that I am stupid and I don't think you can.
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    Quote Originally Posted by playas
    Ok, so how does the antenna produce these binary codes that are emitted within microvaves etc?
    This Wikipedia article describes how the analog carrier (radio waves) are modulated by a digital bit stream.
    http://en.wikipedia.org/wiki/Digital...lation_methods
    Perhaps wert can provide more detail on how this is used for satellite communication.
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    This interests me also. Do standard TV satellite dishes receive only? Or can they transmit to the satellite?

    And do satellite transmitters (whether as part of a receiver or separate, depending on the answer to my first question) use a magnetron, similar to that of a microwave oven, or do they use a different method to generate and transmit microwaves?

    Also, as a side point, would it be ok if people could stop toting IQs at everyone? I find it tiresome as I personally believe that the IQ test is not a very good measure of a person's intelligence, and I don't think it should be used to back up or validate points. Just a suggestion.
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    Quote Originally Posted by Hazz
    This interests me also. Do standard TV satellite dishes receive only? Or can they transmit to the satellite?

    And do satellite transmitters (whether as part of a receiver or separate, depending on the answer to my first question) use a magnetron, similar to that of a microwave oven, or do they use a different method to generate and transmit microwaves?

    Also, as a side point, would it be ok if people could stop toting IQs at everyone? I find it tiresome as I personally believe that the IQ test is not a very good measure of a person's intelligence, and I don't think it should be used to back up or validate points. Just a suggestion.
    'Standard TV dishes' do not transmit back to the satellite. No they do not use magnetrons, they use beam forming arrary elecronics which is essentially lots of small transmitters which are connected in parallel. The reasons for this are many, from heat dissipation to the 'footprint' (which is the area of the earth the satellite transmits to). Also if one 'channel' breaks down it will not significantly degrade the overall performance, and usually there will be a redundant channel which can be switched in. The technology does of course, vary from manufacturer to manufacturer.

    Most TV Geo satellite transmitters are really quite simple, they receive the signal at one frequency (the uplink frequency) and merely re-transmit on a second frequency (the downlink frequency).


    One of the really difficult things on these satellites is getting rid of waste heat, contrary to what you are told the temperature of space when in shadow is not some tremendously cold value. THe truth is, space has NO temperature, only matter has temperature. (if the temperature of space was cold then your themos flask would simply keep it's contents at - 200C or whatever). Heat from a satellite can only be radiated through space so we design the amplifiers to be low power but lots of them.
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  27. #26  
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    Quote Originally Posted by Hazz
    Also, as a side point, would it be ok if people could stop toting IQs at everyone? I find it tiresome as I personally believe that the IQ test is not a very good measure of a person's intelligence, and I don't think it should be used to back up or validate points. Just a suggestion.
    An excellent suggestion. However it will be ignored by anyone who has little else going from them except an ability to do well in IQ tests. (IQ tests are very good at determining who will do well in IQ tests.) Anyway, my IQ is an amazing .... (well, it is a three digit prime number, without zeros, whose digits are in increasing magnitude and no duplicate digits.)
    And, by the way, standard satellite receivers for TV do not transmit back to the satellite.
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    Thank you for clarifying that for me.

    I understand that the military use satellites for communication, and they rely heavily on them for troop deployment, air traffic control etc. One of the Wikipedia articles linked in this thread mentions that the military use the X-band, a certain frequency of microwave, for their satellite communications. I know that certain frequencies of radio are reserved for military use and as such are illegal to listen or broadcast on. Does the same hold true for microwaves in satellite communications? Can a receiver 'receive' beyond its default frequency, and if so does that make it possible to intercept military and civil communications?

    Sorry if this seems suspicious - I am merely curious
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  29. #28  
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    Quote Originally Posted by John Galt
    Quote Originally Posted by Hazz
    Also, as a side point, would it be ok if people could stop toting IQs at everyone? I find it tiresome as I personally believe that the IQ test is not a very good measure of a person's intelligence, and I don't think it should be used to back up or validate points. Just a suggestion.
    An excellent suggestion. However it will be ignored by anyone who has little else going from them except an ability to do well in IQ tests. (IQ tests are very good at determining who will do well in IQ tests.) Anyway, my IQ is an amazing .... (well, it is a three digit prime number, without zeros, whose digits are in increasing magnitude and no duplicate digits.)
    And, by the way, standard satellite receivers for TV do not transmit back to the satellite.
    My point almost exactly. IQ tests are very flawed and should be replaced with a test that measures all aspects of intelligence. Carious research teams have produced many different IQ tests that measure the IQ in different ways, and these should at the very least be combined to make a more accurate IQ test.

    But we are going off topic.
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    Quote Originally Posted by Hazz
    Thank you for clarifying that for me.

    I understand that the military use satellites for communication, and they rely heavily on them for troop deployment, air traffic control etc. One of the Wikipedia articles linked in this thread mentions that the military use the X-band, a certain frequency of microwave, for their satellite communications. I know that certain frequencies of radio are reserved for military use and as such are illegal to listen or broadcast on. Does the same hold true for microwaves in satellite communications? Can a receiver 'receive' beyond its default frequency, and if so does that make it possible to intercept military and civil communications?

    Sorry if this seems suspicious - I am merely curious
    The law in this regard depends very much upon which country you are in. In the UK you are more likely to be prosecuted for using info you eavesdrop (ie listening to police frequencies and passing on information.

    Any sensitive info will be encrypted, if you suceed in decoding then I wouldn't tell anyone if I were you...

    In the UK you could be prosecuted with the Official Secrets Act (no you don't have to sign it to be bound by it).

    Basically as long as you keep the volume down and don't act on, or pass on any information other than commercial stations you should be ok.

    Radio Amateurs usually have the kit to listen to most frequencies from DC to Light so they can ensure they are not interfering with other users.
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    Quote Originally Posted by wert
    Quote Originally Posted by Hazz
    Thank you for clarifying that for me.

    I understand that the military use satellites for communication, and they rely heavily on them for troop deployment, air traffic control etc. One of the Wikipedia articles linked in this thread mentions that the military use the X-band, a certain frequency of microwave, for their satellite communications. I know that certain frequencies of radio are reserved for military use and as such are illegal to listen or broadcast on. Does the same hold true for microwaves in satellite communications? Can a receiver 'receive' beyond its default frequency, and if so does that make it possible to intercept military and civil communications?

    Sorry if this seems suspicious - I am merely curious
    The law in this regard depends very much upon which country you are in. In the UK you are more likely to be prosecuted for using info you eavesdrop (ie listening to police frequencies and passing on information.

    Any sensitive info will be encrypted, if you suceed in decoding then I wouldn't tell anyone if I were you...

    In the UK you could be prosecuted with the Official Secrets Act (no you don't have to sign it to be bound by it).

    Basically as long as you keep the volume down and don't act on, or pass on any information other than commercial stations you should be ok.

    Radio Amateurs usually have the kit to listen to most frequencies from DC to Light so they can ensure they are not interfering with other users.
    Interesting...

    And I completely forgot about encryption. I assume that would be AES, as is the standard for US classified and unclassified data? Although, considering some recent fiasco's with laptops and CDs, I wouldn't be surprised if something unencrypted snuck in.

    Thanks for the info :-D
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  32. #31  
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    Satellites use transponders which simply receive an incoming signal, amplifier it, change its frequency, amplifier it up to 50 - 200 Watts and then beam it back to Earth.

    I think the uplink is in the region of 14 - 18 Ghz for broadcasting satellites. The down link is 10.5 - 12.5 GHz.

    The final amplification is done with a travelling wave tube. A TWT can amplify a low level signal many times. A magnetron is as self oscillating device and cannot be used as an amplifier so it is of no use.

    http://en.wikipedia.org/wiki/Traveling_wave_tube

    Uplinks use high power and large antennas. An amateur 'jammer' would not be able to comptete.
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