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digital TV modulator

Discussion in 'Electronic Design' started by colin, Jun 9, 2007.

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  1. colin

    colin Guest

    Hi,

    Im using my vcr just as a UHF modulator (analogue) but analogue is becoming
    obsolete,
    and im thinking of doing away with the vcr, and getting a tv with digital tv
    tuner but no analogue,
    is there an equivalent modulator for digital TV ?

    I already have UHF coax and I dont want to have to run a multicore cable,
    and it would be so useful if it didnt need a seperate demodulator
    but could just use the internal digital tuner.

    a search for such a thing seemed to show up modulators to connect freeview
    boxes to analgue tv UHF input.

    just need to send it down the tv areal lead,
    or maybe tramsit it a few feet through a wall or ceiling,
    to the next room.

    Colin =^.^=
     
  2. Phil Allison

    Phil Allison Guest

    "colin"

    ** You are on the wrong NG.


    ** No - stupid.


    ** If pigs could fly .....


    ** Get a drill.


    ......... Phil
     
  3. Guest

    All TV is analogue at the receiver at present. You would need an MP2
    encoder for digital - then decode it with a set-top box (like a sky
    receiver) and then re-modulate it in the usual way to show it on a TV.
    Digital TV is a misnomer - the receiver is still analogue after the
    MP2 decoder box - it's the modulation and encoding method that
    differs. Having said that though, LCD TVs are going digital in the
    sense there is no CR tube.

    Wang King
     
  4. Jasen

    Jasen Guest

    yes, they use one at the TV station, it's not equivalent in price
    multicore cable is a whole lot simpler especailly for short runs.

    Bye.
    Jasen
     
  5. colin

    colin Guest

    not if theres no easy way to put in another cable run.

    Colin =^.^=
     
  6. colin

    colin Guest

    The digital TV broadcast is a digitised signal,
    the new TVs with a built in digital tuner can receive the basic digital
    broadcasts with no extra box,
    Im not sure what the modulation sheme is but although the front end
    amplifiers etc may be anlogue,
    the signal still contains digital information, so its still a valid
    distinction.
    some of the newest TVs come with only the digital version tuner can not
    receive the old non digitised fully analogue transmision, its becomeing
    obselete and is being phased out here, as almost everywhere now receives
    digital broadcasts,
    the analogue transmisions will be switched off over the next decade.

    I cant see the advantage of encoding then decoding then modulating as you
    suggested,
    I just want to convert a signal into something that can be received directly
    by a tv with only a digital tuner.
    ie where the tv contains the necessary tuner to demodulate and decode.

    presumably just needs a digitised source of the correct type,
    such as mp2 you mentioned,
    from a pc this is easy, and UHF modulator,
    im not sure what the scheme used is or if theres any control information
    etc.
    the old system was relativly complicated with sound, chroma, luminence
    signals and PAL etc,
    I would think just modulating bits wouldnt be beyond the possibilities of a
    small module.
    a digitizer and mp2 encoder would

    Ive seen you can get USB digital tv broadcast receivers.

    I gues the market just wouldnt be there as it was for analogue when the old
    tvs only had an aerial input and no other way to feed video directly.

    Colin =^.^=
     
  7. Phil Allison

    Phil Allison Guest

    "colin"


    ** Wanna know something....

    You are a real HOOT - Colin.

    Asinine fucking idiots like YOU can often make a living as fifth rate
    stand up comics in sleazy dives run by pimps.

    Could be you best next career move.

    Think about it.

    Whatever.

    **** THE HELL OFF !!!!!!!!!!!!!



    ...... Phil
     
  8. Gary Tait

    Gary Tait Guest

    But what is easier, making a digital modulator, or running another cable?
     
  9. Gary Tait

    Gary Tait Guest

    Not at the consumer level.
    Consider putting a simple tuner/analog demodulator at the TV, if it has
    no analog tuner built in. Or just send composite video to the display,
    and play sound from a separate sound system.
     
  10. colin

    colin Guest

    But wich is more fun ?
     
  11. Jim Thompson

    Jim Thompson Guest

    Best thing I ever did, when we built this house... I had them add 3
    spares of RG-6 between the home theater area and the central cable
    company distribution area.

    ...Jim Thompson
     
  12. colin

    colin Guest

    ive got quite a few cables going through 1 or 2 walls atm,
    rather than put more through I was hoping to mostly get rid of them,
    I also want to be able to move things round a bit easier,
    with a new tv in the main room, I dont have a theater area as such,
    also a new tv in the bedroom where there is no cable or conduit,
    new tvs seem a fair bit cheaper with just the digital tuner rather than
    both.

    it would be ideal to have some wirless system and do away with cables,
    less for the cats to chew through !
    although they dont seem to have chewed thru the usb cable for the kittycam
    by the food bowl.

    if it was possible to send and receive all the audio and all video via the
    same system
    that would be so cool, as there is there are so many diferent systems
    as for wirless you can get microwave video senders, wifi, bluetooth etc ...

    Colin =^.^=
     
  13. krw

    krw Guest

    When my mother built her house, about forty years ago, I put outlet
    boxes with conduit to the attic area for cable and stuff. You never
    know what sorts of cable will be needed. The conduit made it easy to
    snake whatever is needed.

    Sometimes I can snake a cable after, but I've had to open holes in
    walls in this house. It's a PITA and blank wall plates are ugly.
     
  14. joseph2k

    joseph2k Guest

    How about you google for the ATSC standards?
     
  15. Jasen

    Jasen Guest

    in a few years I expect you'll be able to run those signals through a cat6
    network cable, or possibly wireless lan with no loss, but currently there's
    a technology
    called HDMI and a bunch of stupid laws that restrict how you can
    distribute the video signals.

    Bye.
    Jasen
     
  16. Gary Tait

    Gary Tait Guest

    For me, running cable.
     
  17. Gary Tait

    Gary Tait Guest

    Knowing them is one thing.

    Actually making something in a home lab is something else entirely.
     
  18. joseph2k

    joseph2k Guest

    I thought that is what they made medium to large FPGA's development kits
    for. Sure you have to do some Verilog or VHDL, that is the fun part. Can
    you say software defined radio?
     
  19. colin

    colin Guest

    how much could you do in the fpga ?
    just the modulation to feed into a uhf freq shifter ?
    perhaps usb interface that would be usefull,
    or maybe do the mp2 encoding too,
    or even analogue video in too, say composite or whatever,
    although theres probably a chip that would do the a/d nicely,
    or hdmi ...

    if it was a fpga and a uhf mixer that wouldnt be so hard to do,
    although software always takes longer than you want,
    and those fpga are awfully tetchy about being soldered deadbug style,
    i dont know how big those kits are.

    I would imagine just trying to interpret the standards would be hard enough
    judginbg by the way many such things are becoming more and more complex.

    and would anyone else realy be interested ?
    might be cool if there was some shared effort.
    no ones come up with a commercial offering yet so I assume there isnt one,
    save for broadcats studios.


    Colin =^.^=
     
  20. In a few _years_? You can do that today as I've been watching HDTV
    over cat 5 cable for over a year. You need an HD tuner and a home
    network. The computers don't need to be rockets either but you will
    need large drives as HDTV can use up to 8.7 gig/hour.

    GG
     
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