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Digital TV Question

Discussion in 'Electronic Design' started by Phil, Mar 4, 2007.

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  1. Phil

    Phil Guest

    Was at a guys house today and he had a module plugged into his Laptop PC ,
    other end of module had an F connection to Rabbit Ears on his roof , I think
    he was getting the local channels and each channel was sliced up into
    separate services and labeled 9.1 , 9.2 etc , picture was in digital , I
    thought I had an understanding of a 6 Mhz. channel , if anybody knows what
    he is doing I would appreciate knowing , guy said the module cost about $
    125.00 .
    Thanks
    Phil
     
  2. Bob

    Bob Guest

    It was digital teevee (DTV). HDTV is a subset of DTV.

    I believe that the only broadcast DTV is on the UHF channels (that's where I
    get mine). Each 6MHz wide channel contains a modulated signal in the ATSC
    format -- as opposed to NTSC for regular broadcast (analog) tv.

    The modulated signal allows many different "digital channels" to reside
    within that 6MHz bandwidth. The separate digital channels are designated as
    x.y or x-y. For example, 59.1 is KCET's HDTV feed from Mt. Wilson (near
    where I live). 59.2 is their standard resolution DTV version of KCET, but
    right now it has different programming than their HDTV feed as is 59.3. 48.3
    is KOCE which has some amazing HD programming.

    I've where listings of DTV programming refers to sub-UHF channel numbers
    like 9.1 and 9.2, and they map to the real UHF frequencies (e.g., 28.2 and
    28.3). I'm not sure how that's used. When I want to see KCET HDTV then I
    select the external antenna input (the one that has the UHF antenna pointed
    toward Mt. Wilson) and punch 59.2 into my ATSC-capable tv.

    The broadcast HDTV is spectacular. Do yourself a favor and get an HD setup.

    Check this out. Just hit the 'Choose an antenna' button, enter your zip
    code, and see what's available in your area.

    www.antennaweb.org

    Bob
     
  3. Jim Yanik

    Jim Yanik Guest

    Perhaps the module was a digital TV tuner.
    HiDef Tv is xmitted on two 6Mhz channels,regular digitalTV on one.
     
  4. Jim, you got it wrong this time (or was it just a typo?). The
    broadcasters are indeed running 2 6MHz channels, the original NTSC on
    one and the DTV (including HDTV) on the other. You can find the
    channel assignments here.

    http://www.nab.org/AM/ASPCode/DTVStations/DTVStations.asp

    The broadcasters are allowed to run up to 4 std def or 1 HD and 2 SD
    channels on their carrier. I 've read about a station (in Texas?)
    running 2 HD channels on the 1 carrier.

    How the ATSC signal is created is pretty well explained here

    http://www.broadcast.net/~sbe1/8vsb/8vsb.htm

    In Feb of 2009, the NTSC transmitters will all be turned off. In LA,
    channels 7, 9, 11 and 13 will become the DTV channels. Currently their
    DTV assignments are all >51. Channels 51 (or is it 50?) through 69
    will be re-allocated for other purposes. Low-band VHF is poor for DTV
    and you are unlikely to see any DTV in channels 2-6

    As for the tuner, these folks (and others) make USB DTV tuners not
    much larger than a flash drive.

    http://www.hauppauge.com/

    A guy I work with bought the WinTV-HVR-950 and the WinTV-HVR-1600 last
    week for his Mac laptop and PC desktop. He got them both for $200 and
    is very pleased with them. As for HDTV on the laptop, you WILL see a
    significant improvement over analog TV even on the small screen.

    GG
     
  5. There's a station here in houston that is running 5 digital SD channels and
    no HD, go figure.

    They all look bad, but that's the source material I believe.
     
  6. Joerg

    Joerg Guest

    Comes up with about three digital ones we could possibly receive unless
    our heavy multipath issue ruins it. Not a lot, considering that the
    switch was supposed to happen many moons ago and is now anticipated for
    2009. Plus I fail to see converter boxes at the stores.
     
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