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opposite of an RF Modulator?

Discussion in 'Electronic Repair' started by mm, May 20, 2010.

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  1. mm

    mm Guest

    Does there exist the opposite of an RF Modulator? Something that will
    take RF and turn it into digital for a digital tv?

    I don't need this yet but I'm trying to plan ahead. What will I do
    when I have one or two digital tvs, but I'm sending analog to all the
    tvs in the house? I don't have the energy anymore to install
    homeruns from the DVDR to any tv but the one in the same room. All
    the rest are in series ther. I don't have the energy to run RCA
    cables for composite or component inputs.

    Right now, I use a DVDR and an RF modulator to take digital over the
    air tv, detect it, and convert it to analog. and I send it to the 7
    tv's I have, one in each room, and maybe one for the deck too. After
    some effort, with some help from you guys, this works fine. The attic
    antenna goes to the DVDR in my bedroom and soon, I'll have a set-top
    box too (and a Channelplus modulator outputing two inputs on separate
    channels), so I can record one show and watch a second, while sending
    the second throughout the house.

    I'm not going to buy 8 digital tv's at one time, and in reality, I'm
    only going to get them one at a time over the next 10 or 20 years,
    dpending on what I see at yard sales.

    So what will I do when I have one or two digital tvs, but I'm sending
    analog to all the tvs? I don't have the energy anymore to install
    homeruns from the DVDR to any tv but the one in the same room. All
    the rest are in series. I don't have the energy to run RCA cables for
    composite or component.

    Can I convert the analog back to digital for the digital tvs?
  2. Rich Webb

    Rich Webb Guest

    [snippety snip]
    Some (many? most? all?) current generation U.S. flat-screen television
    receivers include both NTST (analog) and ATSC (digital) tuners. The NTSC
    tuners work the same way on the flat-screens as they do for the older,
    CRC-based models, so you may not need to make any changes to your
    distribution system at all.
    Not easily or cheaply. The consumer-grade market for such a gizmo is
    very small. If you wanted to do the heavy lifting, the specs for each
    are available and it certainly could be done in principle. Some guy with
    a web page has probably already done it but you're not likely to find
    one on the shelf at WalMart.
  3. I think this is a troll, but...

    To make a long story short... Almost all TVs have inputs for analog audio
    and video. By that I mean "baseband" (not RF) signals, such as composite
    NTSC or component 1080p. With high-quality cabling, you should be able to
    run these signals to multiple sets.
  4. UCLAN

    UCLAN Guest

    Well, a RF *demodulator* takes analog RF and converts it to analog A/V. A
    A->D converter will convert that to digital.
    A A->D converter will do the trick. $$ for video.

    Question: For the digital TVs, why not just use the original digital
  5. Just curious: what *is* the impedance of such cables? I'm guessing it's
    not the 50 or 75 ohms of RF cabling.
  6. mm

    mm Guest

    I don't know. I guess I can. I didnt' think of it. Thanks.

    I guess I would have to use a couple spitters to make a route around
    the RF modulator, and then I would be running analog and digital on
    the same co-ax, right?
  7. mm

    mm Guest

    Well that would be great. I'll keep my eyes open for that.

    Thanks to you and to Bob, AZ, David, William (even though he thinks
    I'm trolling!) Jim, David, Michael, and UCLAN.
  8. Thanks to you and to Bob, AZ, David, William (even though
    There are some questions that -- to me, anyway -- have such obvious and
    simple answers, that it's easy to believe some posts are trolls.
  9. UCLAN

    UCLAN Guest

    If you split it off to the digital TVs *before* it goes into the D->A
    converter box, then it would be only digital - right?
  10. Guest

    Phrase your question properly and you will get better results.

    Google 'ATSC Modulator'.

  11. Guest

    Only if you are willing to settle for 'less than analog boradcast
    quality signals'. Recall that anyone who compared the quality of the
    RF signal output of a VCR to the composite signal quickly decided that
    it was worth buying the composite cables. And a component connection
    offers even better performance.

    Also, unlike others, I do a little research. The last two DVD players
    I purchased don't even have RF outputs. One, a Toshiba, DOES have an
    HDMI output.

    Doing a little research, the ZvBox® 170 appears to do exactly what
    the OP proposed. Not surprising, that's what it was designed for.

  12. UCLAN

    UCLAN Guest

    Well try reading what is posted instead. It was stated that the best quality
    video would be with HDMI, with component, S-Video, composite and RF trailing
    in descending order. Correct statement. Not sure how your "boradcast" signals
    would differ (if at all.)
  13. Guest

    It has been pretty well established that the best possible display in
    a HDTV is with a Blu--Ray player and an HDMI connection. It goes
    without saying that the HDTV must be capable of 1080P performance
    (although all intelligent people agree that 1080I is pretty darn
    close), with lower resolutions (of both the source signal and the
    native resolution of the display) giving poorer results.

    What is often ignored is the fact that an antenna that gives a good
    signal and a broadcaster that does not limit their signal quality in a
    number of ways (IE, broadcasting in 720P) will give a picture that is
    ALMOST as good as Blu-ray. The chief deficiency is, of course, that
    OTA broadcasts are either 1080I or 720P.

    Given the OP's desire NOT to run additional cables, and a desire for
    sharing top quality signals with all TVs, it thus follows that he must
    use an ATSC modulator for each source and combine them onto the single

  14. UCLAN

    UCLAN Guest

  15. Guest

    *+-I don't know if those outputs are made to drive -multiple- sets.
    *+-I believe they are only 1:1.

    Ouch. Pet peeve.

    I had learned to "design fan out of five", so I had a y-connector
    using 2,3,8,20 RS232 pins for terminal and printer to modem. Then in
    1983 I got an Epson computer, and they didn't support fan-out of
    five. It was more like 150% instead of 500%.

    THe Fan out of five equipment was all American made. So I never
    bought the "Japanese quality" myth. (My family has been orginal owner
    for twenty years each on five USA-made V8 cars built 1960-1980.)

    - = -
    Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
    ---{Nothing herein constitutes advice. Everything fully disclaimed.}---
    [Homeland Security means private firearms not lazy obstructive guards]
    [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]
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