Satellite Receiving In one Receiver ...!

Discussion in 'General Electronics Chat' started by RRITESH KAKKAR, Sep 3, 2010.

  1. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    Pls, tell how to receive two satellite in one Dish by using some circuit....?:confused:
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,148
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    A dish antenna has a narrow angle for the satellite to be in in order to receive a signal. Two receivers can listen to two different satellites using the same dish without any problem at all if the satellites are at the same azimuth and elevation. I'm assuming the satellites are using different downlink frequencies.
     
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  3. marshallf3

    Well-Known Member

    Jul 26, 2010
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    RRITESH KAKKAR - you must have over a dozen posts running around on here, all unrelated and 99% of which could have been just as easily answered with a search engine.

    Trying to learn electronics is fine but can't you at least put in a little effort on your own?
     
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  4. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    Sir, I like this forum & it explain very well.......!

    ok, as you are saying to receive in one dish but friend the satellite angle is not so close can't receive in one dish what to do for far satellite angle....?
     
  5. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Some satellite dishes have more than one LNA that pick up on slightly different focus points of the modified parabolic dish they're attached to. These multiple LNAs may even be in the same enclosure. In that manner there can be several satellites in space that are spaced fairly close to each other in orbit and through the magic of electronics the satellite of interest can be selected merely by switching the output signal to come from the LNA of choice.

    There are also methods that involve signal polarization switching and allowing the electronics that follows the LNA outputs to zero in on the more powerful of the simultaneously received signals.

    Different modulation schemes can be employed and I'm sure there are plenty of other tricks they've come up with in the past few years.
     
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  6. Potato Pudding

    Well-Known Member

    Jun 11, 2010
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    What you do in that case is you put the second LNB at an offset. You have to find the focus point for it. For dual receiving you can offset both LNBs to either side of center and point the dish in between the sattelites.

    This is pretty sophisticated stuff so good luck with it.

    If the satellites are more than 5° separation then you want to get a second dish.

    There are actuators that will physically move a dish but those are uncommon with the modern small dishes.

    It is cheaper and more reliable to just get a second dish.
     
    Last edited: Sep 3, 2010
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  7. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I know they've changed terminology around over the past 30 years but historically - in the 10' dish days - the LNA was the detector and preamp circuit. The LNB was the downconverter that took the raw RF at exactly the frequency it was transmitted at and converted it down to an intermediate frequency. The local oscillator in the LNB allowed you to select the frequency of interest and the output of same mixing circuit was a fixed frequency that went on down the feed line and into the receiver.

    Not too many years later the LNA and LNB were combined into one enclosure and dubbed as an LNC. What you would have on a Dish Network or DBS system dish would technically be an LNC.

    BTW: If you've got any old satelllite shops still around - ones that have been around long enough that they used to work on the older C band systems - see if they still have a junk pile hidden in the back.

    In the beginning the only satellite available to consumers was Galaxy 1. It had 24 channels that alternated in polarity - I think the odd numbers were vertical and the even numbers were horizontal. Regardless, due to only one satellite, there were a ton of 10' dishes that were just aimed and welded to point directly at G1. Sadly satellites tended to drift a little so every now and then you'd have to get someone to break the weld and reaim it or, if it was put together properly in the first place it could be reaimed by loosening the mounting screws and going from there.

    My reason of mentioning the junk pile? It wasn't long until we had more than one satellite and positioners came into being. Most of the early ones were their own box, it wasn't until later that they started integrating the arm positioning circuit into the receiver. The early positioning arms took a lot of current to drive - even at the 24V or 36V most ran on. This required that these old positioning boxes or receivers that contained them had rather large power transformers in them. Toroids were just coming into popularity as the best thing since movies started serving popcorn so that's what was normally used in the power supply.

    If you find a guy that's been around since the C band era and still has a pile of old junk see if you can talk him out of a pile of the positioners &/or antique receivers that contained them. You'll often open them up to find a 24V or 36V power supply toroid that's capable of 4A or better. A few evenhad tapped secondaries but these were rare.

    I need not say that having a few of these toroids around can be handy.
     
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  8. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    I have listen of 22khz switch & Diseqc how to make it pls tell......?
     
  9. marshallf3

    Well-Known Member

    Jul 26, 2010
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    You on something over there? What does 22 KHz have to do with anything and what the heck is a Diseqc?

    Do you honestly think anyone else is going to understand what you posted?

    I must be the exception to the rule around here but even if I could understand half of what you keep asking do you think I'd stop everything and spend the rest of the day trying to design and explain something - even if I knew what the heck it was?

    Satellite receivers are free from the satellite channel providers and must be professionally installed, aligned and you've got to pay by the month for the programming. There is still a lot of free programming in the C and Ku bands if you want to go out and buy all the proper equipment, have it installed and then learn how to operate it.
     
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  10. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    I have tuned many ku band satellite dish but i really what to have watch then in a single STB....!
     
  11. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You will need to re-position your satellite dish in order to select a different satellite.

    Other methodologies and their limits have already been explained.
     
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