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  • Satellite reception - same mux frequency but receiver can decode with t

    From NY@21:1/5 to All on Wed Aug 21 20:59:07 2024
    I receive 28.2 satellite using a DVB-S2 USB tuner (PCTV 491e) and TV
    Headend software on a Raspberry Pi.

    As I was going through the list of multiplexes that are configured into
    TV Headend, I found several muxes which duplicated but with different
    symbol rates, modulation and FEC. Nothing unusual there: I imagine that
    the parameters have changed over time and TV Headend has discovered the
    new settings but has not deleted the old ones.

    But there is something very weird. In most cases of duplicates, one
    works and one doesn't. But for 12090V, I have two different entries
    which both work equally well:

    DVB-S2
    freq 12090000
    sym rat 29500000
    pol V
    mod QPSK
    FEC 8/9

    and

    DVB-S2
    freq 12090000
    sym rat 27500000
    pol V
    mod PSK/8
    FEC 2/3

    How can this work?

    https://www.lyngsat.com/muxes/Astra-2E_Europe-Ku_12090-V.html and https://en.kingofsat.net/pos-28.2E.php say that the first (29500000)
    values are the correct ones.

    Should a satellite receiver be able to tune to a mux and to decode the
    basic tables such as the one which lists the channels within the mux, if
    the parameters are wrong?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Woody@21:1/5 to All on Wed Aug 21 21:22:06 2024
    On Wed 21/08/2024 20:59, NY wrote:
    I receive 28.2 satellite using a DVB-S2 USB tuner (PCTV 491e) and TV
    Headend software on a Raspberry Pi.

    As I was going through the list of multiplexes that are configured into
    TV Headend, I found several muxes which duplicated but with different
    symbol rates, modulation and FEC. Nothing unusual there: I imagine that
    the parameters have changed over time and TV Headend has discovered the
    new settings but has not deleted the old ones.

    But there is something very weird. In most cases of duplicates, one
    works and one doesn't. But for 12090V, I have two different entries
    which both work equally well:

        DVB-S2
    freq    12090000
    sym rat    29500000
    pol    V
    mod    QPSK
    FEC    8/9

    and

        DVB-S2
    freq    12090000
    sym rat    27500000
    pol    V
    mod    PSK/8
    FEC    2/3

    How can this work?

    https://www.lyngsat.com/muxes/Astra-2E_Europe-Ku_12090-V.html and https://en.kingofsat.net/pos-28.2E.php say that the first (29500000)
    values are the correct ones.

    Should a satellite receiver be able to tune to a mux and to decode the
    basic tables such as the one which lists the channels within the mux, if
    the parameters are wrong?

    This might help:-
    https://www.astra2sat.com/forward-error-correction-fec/

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Andy Burns@21:1/5 to All on Sat Aug 24 10:29:28 2024
    NY wrote:

    for 12090V, I have two different entries which both work equally well:

        DVB-S2
    freq    12090000
    sym rat    29500000
    pol    V
    mod    QPSK
    FEC    8/9

    and

        DVB-S2
    freq    12090000
    sym rat    27500000
    pol    V
    mod    PSK/8
    FEC    2/3

    Are you sure they're both vertical polarisation?


    I'm away from my TVheadend at the moment, socan't check, but I do
    remember some muxes where there was a H and a V on the same frequency ...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From NY@21:1/5 to Andy Burns on Sat Aug 24 20:21:29 2024
    On 24/08/2024 10:29, Andy Burns wrote:
    NY wrote:

    for 12090V, I have two different entries which both work equally well:

         DVB-S2
    freq    12090000
    sym rat    29500000
    pol    V
    mod    QPSK
    FEC    8/9

    and

         DVB-S2
    freq    12090000
    sym rat    27500000
    pol    V
    mod    PSK/8
    FEC    2/3

    Are you sure they're both vertical polarisation?


    I'm away from my TVheadend at the moment, so can't check, but I do
    remember some muxes where there was a H and a V on the same frequency ...

    Yes, I'm wise to the muxes where there is a vertical and a horizontal
    mux on nominally the same frequency. 11344H and 11344V is an example.

    It's a weird one. All other duplicate muxes have one entry which works
    and another entry that doesn't, and they have different symbol rate, multiplexing and FEC, which leads me to believe that if any of those are changed, the tuner can no longer connect. But 12090V seemed to be an
    exception. I've deleted the old entry 27500000, PSK/8, 2/3.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)