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  1. #21
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    Re: Satellite Internet working

    I also have a steerable
    Hello what is this?
    how you learn so much?
    The highest frequency co-ax can carry depends on it's construction, diameter and whether it has bends in it.
    how the co-axial is constructed how diameters play role in AC freq
    i can understand in DC.



    •   Alt13th June 2016, 16:45

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  2. #22
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    Re: Satellite Internet working

    Hello,
    i got this chart
    Coax Cable Signal Loss (Attenuation) in dB per 100ft*

    in my DTH Satellite reciver the frequency must be higher than 1GHZ range .
    so, there is no chart in this.
    anyway if we aplies less freq co axial what wi happen?
    http://www.w4rp.com/ref/coax.html

    - - - Updated - - -

    Hello,
    i got this chart
    Coax Cable Signal Loss (Attenuation) in dB per 100ft*

    in my DTH Satellite reciver the frequency must be higher than 1GHZ range .
    so, there is no chart in this.
    anyway if we aplies less freq co axial what wi happen?
    http://www.w4rp.com/ref/coax.html

    - - - Updated - - -

    Hello,
    According to this video
    https://www.youtube.com/watch?v=EBwos911pkw

    the co-axial wire are used in computer data but i have never seen it.



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    Re: Satellite Internet working

    Quote Originally Posted by RITESH KAKKAR View Post
    in my DTH Satellite reciver the frequency must be higher than 1GHZ range ..
    The signal is down converted at the dish LNB itself: the local osc frequency is sent up the cable (and the power for the LNB) - this also selects the tuning channel. The IF result is received by the same cable back to the set top box.


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    Re: Satellite Internet working

    That's right, at the dish you will see a box with an inlet (the antenna waveguide) mounted at it's focal point. The box is called a "LNB" (Low Noise Block converter) and it's purpose is to down-convert the satellite broadcast frequencies so they are low enough that normal co-ax can carry them. The co-ax also carries DC from your set top box up to the LNB to provide it with operating power.

    The frequencies used will vary from one satellite to another but as an example:
    The satellite channels cover 10.75 to 11.5 GHz
    The LNB down-mixes with a 10GHz oscillator
    The co-ax carries 0.75GHz to 1.5GHz to the box indoors.

    There are also numerous other control signals sent from the set-top box to the LNB to select the antenna polarization and usually to select more than one oscillator frequency. You are normally not aware that these signals are controlling the dish as they are sent automatically as you change channel.

    how you learn so much?
    Ask again when you also have 50 years experience, but by then you would know the answer anyway!

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.


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    Re: Satellite Internet working

    Quote Originally Posted by RITESH KAKKAR View Post
    how you learn so much?.
    Standing on the shoulders of Giants...

    Surely you do not know how a basic AM radio works. The history itself is fascinating...


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    Re: Satellite Internet working

    The signal is down converted at the dish LNB itself: the local osc frequency is sent up the cable (and the power for the LNB) - this also selects the tuning channel. The IF result is received by the same cable back to the set top box.
    ok, I have listen of this term LNB
    but now i understand the use of it.
    yes i have seen the circuit in it is large scale integration.
    Does LNB has oscillator like micro controller ?
    IF
    what is IF here?
    and there are two pins of 15mm i think at 90 degree what they function?

    - - - Updated - - -

    "LNB" (Low Noise Block converter) and it's purpose is to down-convert the satellite broadcast frequencies so they are low enough that normal co-ax can carry them. The co-ax also carries DC from your set top box up to the LNB to provide it with operating power.
    OK, Coaxial also carries DC at what voltage and current?
    can one wire can carries dc volatge with signal of GHZ with information?
    There are also numerous other control signals sent from the set-top box to the LNB to select the antenna polarization and usually to select more than one oscillator frequency. You are normally not aware that these signals are controlling the dish as they are sent automatically as you change channel.
    In my STB there are 470 channel and there is software which update with satellite.
    how these work very fast there is IBM processor in circuit.



    •   Alt14th June 2016, 11:45

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    Re: Satellite Internet working

    Does LNB has oscillator like micro controller ?
    IF
    what is IF here?
    Yes, very much like the oscillator in a microcontroller but at a much higher frequency. Instead of Quartz crystal they usually use special ceramic devices called "dielectric resonator oscillators" (DRO). If quartz was used it would be so incredibly tiny that it couldn't be manufactured economically. A typical ceramic resonator is a disc of maybe 5mm diameter and 3mm height. The IF (intermediate frequency) of an LNB is normally the incoming frequency from the satellite minus the frequency of the local oscillator, for example 11GHz from the satellite minus 10GHZ from the DRO produces 1GHz IF. The idea of 'block' converting is the IF bandwidth is very wide, it doesn't tune to one particular frequency, it downshifts a wide range of frequencies at once. The final selection of the satellite signal is done by a narrower band filter (the tuner) inside the set-top box by your TV.
    and there are two pins of 15mm i think at 90 degree what they function?
    I can not tell without seeing them. They could be the antennas, one horizontal and one vertical or some kind of signal coupling lines.
    OK, Coaxial also carries DC at what voltage and current?
    can one wire can carries dc volatge with signal of GHZ with information?
    It varies from one LNB to another but typically, the DC is switched between around 15V to 20V to tell the LNB which polarization to use and there may also be burst of data using 22KHz tones to switch local oscillator frequency. Search for "Disecq" for more information. The current depends on individual LNB designs but is normally around 100mA.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



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    Re: Satellite Internet working

    dielectric resonator oscillators" (DRO)
    what is the cost of it and how it look?
    where it is used other than LNB?
    and there are other oscillator inside STB.


    for example 11GHz from the satellite minus 10GHZ from the DRO produces 1GHz IF.
    How can we do this will this not result in damage to signal?
    and satellite has huge number of data how LNB work with this?
    how LNB is designed?



    •   Alt14th June 2016, 14:26

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    Re: Satellite Internet working

    oand there are two pins of 15mm i think at 90 degree what they function?.
    These two are the antenna- they receive the signal focussed onto the LNB by the dish.

    There are two of them: one is for vertical polarization and the other for the horizontal polarization, is it clear?

    Most commonly the two will be used together and the LNB will use it for detecting a circularly polarized signal. There are two types of circularly polarized signals- left and right.

    IF stands for intermediate frequency- in an AM radio the IF is 455kHz- which is easy to filter and amplify and process before collecting the audio.



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    Re: Satellite Internet working

    polarization
    Hello,
    I have seen many times H and V polarization in DTH what does polarization mean here?

    - - - Updated - - -

    betwixt

    Hello,
    So after learning lot of things what you can design ?
    can you design STB or what?

    - - - Updated - - -

    hello,
    which modulation is used in satellite dish?

    http://hydrogen.physik.uni-wuppertal...gaud/hdyne.gif



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    Re: Satellite Internet working

    Quote Originally Posted by RITESH KAKKAR View Post
    hello,
    which modulation is used in satellite dish?

    http://hydrogen.physik.uni-wuppertal...gaud/hdyne.gif
    I was wondering if there was a dearth of information on this subject so I typed "satellite modulation techniques" into google and it gave me the following results: https://www.google.com/webhp?sourcei...n%20techniques, I checked out about 4-5 of the sites given and they all give you what you want.

    I think you need to hone your internet research skills.
    http://www.scholastic.com/teachers/a...-students-need
    http://www.sweetsearch.com/TenSteps
    these are a couple of sites that might help in that respect.



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    Re: Satellite Internet working

    which modulation is used in satellite dish?
    Neither the satellite dish nor the LNB are determining the modulation.

    Different services are using different modulation methods. Digital services (digital TV, satellite internet) are e.g. using QAM variants. I doubt that discussing the modulation details is essential for this thread.

    So after learning lot of things what you can design ?
    can you design STB or what?
    An experienced engineer can design virtually everything, but not without studying many project details.

    "Designing a set-top box" mainly involves choosing a chip set respectively application processor, applying or slightly modifying a reference circuit and writing software, software, software...



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    Re: Satellite Internet working

    So after learning lot of things what you can design ?
    can you design STB or what?
    As FvM stated, I can design almost anything given enough information and time. So can you!

    Some of the things I've designed:
    Two fully automated (unmanned) microwave TV stations - and built one of them from scratch (took about 2 years!).
    Various point-to-point microwave TV links.
    Many automatic telecoms test sets, including all hardware, software and pneumatics.
    Control systems for solar water heating installations.
    Lots of RFID and coded security systems.
    Braking systems for trains in France.
    Aircraft landing gear controls.
    Automatic stall detection and correction system for surveilance aircraft (Thailand Police).
    Flood detection and alarm systems.
    Emergency lighting systems for buildings.

    I've never designed a STB though - but I know how they work.

    And I've worked for companies in the UK, Ireland, USA, Austria, Hungary, Romania and Thailand. For a high school drop-out with no qualifications I've done quite well!

    The trick is to be inquisitive but as already mentioned, you should learn how to search for information yourself and fully understand it before moving on to something else. Asking lots of questions will give you lots of answers but it will not help you to grasp the way each topic interacts with others. It is from a good understanding of the basics of electronics that you will understand the answers to all your specific questions.

    Brian.
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    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



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    Re: Satellite Internet working

    hello,
    Mostly i have seen company designing product with thousandth or hundred of people.
    but you alone designed this great work.
    how should i learn?
    and design products?

    Braking systems for trains in France.
    Is it contain mechanical components??

    Many automatic telecoms test sets, including all hardware, software and pneumatics.
    what is it?
    telecom is tower of communication.



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    Re: Satellite Internet working

    how should i learn?
    Read a lot, understand a lot, ask questions as a last resort. See if local schools or colleges run electronics courses you can join.

    Is it contain mechanical components??
    In that product there were wheel rotation sensors (magnetic reluctance sensors) and inputs from the speed control and braking controls. It calculated the amount of braking power needed and produced a PWM signal to the brake actuators. If the brakes were failing or the speed was too high, it sent an alarm signal to the driver. It was mostly a software product but had some interfacing components to process the input signals and provide the required PWM drive voltages.

    what is it?
    I worked on the PEDC Project (Pan-European Digital Cellular) which later became GSM , now the digital cell phone system used throughout the world. After that, I designed and built fast automated telephone testers. They were quite big machines that sat at the end of telephone production lines, they automatically checked the function of all the telephone buttons by pressing them with pneumatically driven 'fingers', did line impedance and voltage/current checks, operated all the switches, checked the ringer volume, used video pattern recognition to check LCD displays and LEDs were working and finally did frequency sweep checks to make sure all the audio paths were withing specification. A large office telephone with an LCD display and lots of features would have all it's features tested in about 30 seconds. I don't know how many phones went through the testers but it was more than 10,000 per week.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



    •   Alt15th June 2016, 09:32

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  16. #36
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    Re: Satellite Internet working

    I designed and built fast automated telephone testers.
    Hello,
    Mobile is also embedded system so, what type of micro controllers are used.
    I have seen some people repair mobile what they do in it?

    - - - Updated - - -

    I have seen Mobile tower and operator records all calls why?
    they record text sms also?
    and where they store huge data?
    does in india any company make telecom communication device or all are imported?



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    Re: Satellite Internet working

    I see that the original question has been answered.

    The discussion is completely running off-topic now, thread closed.


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