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Audio sync problem on ABC News 24 (HD)

Discussion in 'Hobby Electronics' started by Franc Zabkar, Nov 11, 2012.

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  1. Franc Zabkar

    Franc Zabkar Guest

    I have two LG LCD TVs, one relatively new, the second quite a few
    years older. Both exhibit temporary audio sync problems when first
    switching to the channel. The problem usually resolves itself within
    about 20 seconds, but on one occasion it peristed, on both sets, for
    two days.

    Is this a firmware bug, or is it a transmission anomaly, perhaps due
    to a weak signal? The video is perfect, and the audio remains in sync
    until the channel is changed. Sometimes sync can be restored by
    channel surfing to News 24 from the lower ABC channels.

    - Franc Zabkar
     
  2. Grant

    Grant Guest

    I suggest you have low signal issue, only problem I see is the initial
    LCD TV startup del;ay before the tuner gets going properly.
     
  3. Sylvia Else

    Sylvia Else Guest

    It seems highly unlikely to be a weak signal effect.

    The audio and video streams have timestamps to show how they're to be
    synchronized. If these were simply wrong, you'd expect to see lots of
    complaints.

    What may be happening though, is that the ABC24 streams are either not
    strictly compliant with the standard, or are pushing the limits. This
    can result in most decoders getting it right, but some, like yours,
    getting confused.

    Of course the problem is that while you're trying to get a solution,
    what you actually get is a run-around, with the ABC and LG assuming that
    the other is at fault.

    Sylvia.
     
  4. Franc Zabkar

    Franc Zabkar Guest

    My signal is boosted by a masthead amplifier. Analogue reception was
    OK when boosted, but usually very poor otherwise. The DTV signal
    strength bar is well into the good section, so I can't believe that
    signal strength is an issue. Other digital ABC channels have never
    exhibited this problem.
    I'll see what LG has to say. Maybe there are firmware updates. I also
    have a HD STB that I could try.

    - Franc Zabkar
     
  5. Franc Zabkar

    Franc Zabkar Guest

    You're right. I rang LG and told them of the problem. It affects my
    two most recent sets (42LD460 and 37LG30D), but not the older one
    (32LC7D), so one would think that a firmware update would resolve the
    issue. The 37LG30D is the worst offender.

    LG's customer service acknowledged that a problem existed, but that it
    was the ABC who were at fault. They claimed that they were currently
    in communication with the ABC regarding the problem.

    - Franc Zabkar
     
  6. Phil Allison

    Phil Allison Guest

    "Franc Zabkar"

    ** You still live in Shoalhaven, NSW - right ?

    TV signals come from Knights Hill ( about 30 kms away to the north ) from
    well sited towers that have a commanding view of the area. Analogue signals
    went off the air in June this year and all signals are UHF.

    That your analogue signal was very poor until boosted at the antenna and
    then just " OK " is suspicious - suggests you have unusually long or poor
    quality co-ax cable installed.

    The problem you describe is associated with weak signal conditions or where
    there is interference and/or ghosting.

    With NO broadcast analogue signal to view, it becomes a BIG problem to
    figure out WTF is going on with TV signals.

    The same problem will hit Sydney in about one year.


    ..... Phil
     
  7. terryc

    terryc Guest

    You need to talk to a good speech therapist or an older experienced
    teacher in this matter. Almost once a night I hear "that is not
    synchronised". I don't know what the time accurracy of the time stamps
    are, but even i can spot it on vaious programs at times on Tv signals.
     
  8. Phil Allison

    Phil Allison Guest

    "Franc Zabkar"
    ** That sounds like a reference to that two day out of sych event


    ** That the synch comes good after 20 seconds indicates no inherent problem
    with the DTV signal, other than it is weak or suffering from ghosting etc.
    See my other post.


    ..... Phil
     
  9. Sylvia Else

    Sylvia Else Guest

    I don't know what you intend by that. The time stamps don't have an
    accuracy in any real sense. They just specify how the streams should be
    aligned.

    Sylvia.
     
  10. Sylvia Else

    Sylvia Else Guest

    Bearing in mind that this is a multiplexed digital data stream, the
    effects of a poor signal will be data corruption and/or data loss.
    Either way, one wouldn't expect to see the described behaviour which is
    that once the sync comes good, it stays good. Rather, one would expect
    the sync to be lost again from time to time.

    Sylvia.
     
  11. Phil Allison

    Phil Allison Guest

    "Stupider than Anyone Else Alive"

    ** It is a widely observed reality.

    Reality does not give a flying **** what fools *expect* it to be.



    ..... Phil
     
  12. Sylvia Else

    Sylvia Else Guest

    Few people who see the effect would be capabable of observing that it is
    caused by a poor signal, so I dispute your claim that it is a widely
    observed reality.

    Sylvia.
     
  13. Phil Allison

    Phil Allison Guest

    "Stupider than Anyone Else Alive"

    ** Nonsense.

    Fix the weak / ghosty signal on the PARTICULAR channel and problem gone.

    Only fools argue from a position of ignorance and that is the only position
    you have.



    ..... Phil
     
  14. Sylvia Else

    Sylvia Else Guest

    "particular" channel?

    Franc cites an issue with ABC News 24 (HD), which is only one of the
    programs to be found multiplexed on the ABC network signal. He appears
    to have had no problems with any other program on that multiplex.

    Sylvia.
     
  15. Phil Allison

    Phil Allison Guest

    "Stupider than Anyone Else Alive"
    ** Yep.

    Signal strength and interference effects like ghosting and EMI vary widely
    from one channel to another.

    ** Not relevant to the topic.

    BTW: Franc is a bullshitting idiot.



    .... Phil
     
  16. Sylvia Else

    Sylvia Else Guest

    ABC1, ABC2 and ABC24 [*] are all transmitted as part of a SINGLE bit
    stream. There is no conceivable way that signal strength and
    interference effects could impact on ABC24 but not on ABC1 and ACB2.

    Sylvia.

    [*] And some other stuff.
     
  17. Phil Allison

    Phil Allison Guest

    "Stupider than Anyone Else Alive"
    ** Absolute crap !!!!!!!

    FFS read up on how Australian DTV really works.


    ** Utter garbage, the HD signal from ABC24 has a much higher data rate for
    starters.


    As per fucking USUAL you have over snipped and ignored two most important
    facts:

    Fact #1

    " Only fools argue from a position of ignorance and that is the only
    position you ever have. "

    Fact #2

    " Franc is a bullshitting idiot."

    Plus the over riding fact that YOU are a know nothing, raving nut case
    bitch.

    FOAD.



    .... Phil
     
  18. Sylvia Else

    Sylvia Else Guest

    I did. A good while back. It's you who have a flawed understanding.
    More of the bits in the single bit stream are allocated to ABC24. So it
    has a higher *average* bit rate. But the bits for the other channels
    *when they are arriving* do so at the same rate. Since fewer of then are
    allocated to those channels, those channels have a lower *average* bit rate.

    Sylvia.
     
  19. Phil Allison

    Phil Allison Guest

    "Stupider than Anyone Else Alive"

    ** Its NOT a single bit stream in this country.

    **** off.


    ..... Phil
     
  20. Franc Zabkar

    Franc Zabkar Guest

    Thanks very much for that insight. I found the following article.

    "What is the difference bewteen a Digital and a RF TV channel?"
    http://vk3khb.gak.net.au/atv/dtv-chnls.html

    ====================================================================
    In the old system one TV channel equated to one "Radio Frequency" RF.
    In the new system many TV channels share the one Radio Frequency. As
    many Digital TV channels can effectively hide inside one RF TV channel
    some additional addressing must be used. These Digital TV channels are
    allocated as "Logical Channel Numbers" or "Digital Streams".
    ====================================================================

    Logical Channel Number 2 (RF Channel #12) is assigned to the ABC. In
    Melbourne the single frequency is 226.5 Mhz.

    The one bit stream incorporates all the following channels:

    02 ABC 1
    21 ABC1
    22 ABC2/4
    23 ABC3
    24 ABC NEWS
    200 ABC DiG Radio
    201 ABC DiG Jazz

    - Franc Zabkar
     
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