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Re: [MSG-1] Re: Strange light effect

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  • David J Taylor
    ... Ernst, The dip in signal-to-noise is caused by the sun being within the beamwidth of the dish, and the times can be predicted by my WXtrack program. The
    Message 1 of 34 , Mar 1, 2012
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      > Hi Alan
      >
      > My combined EUMETCast/DDS receivers showed between 11:20 and 11:35 UTC
      >
      > - A dip in SNR of the EUMETCast receivers
      > - High BER and PLL lock lost for DDS (!)
      >
      > You can zoom all my eLuna/RRD plots. See e.g. here:
      >
      > http://212.117.122.202:83/eluna/index.pl?rrd=18_snr1&type=c&time1=2012-02-29+11%3A00&time2=2012-02-29+12%3A00
      >
      > Cheers
      > Ernst

      Ernst,

      The dip in signal-to-noise is caused by the sun being within the beamwidth
      of the dish, and the times can be predicted by my WXtrack program.

      The effect which Alan and Ulrich noticed may have been caused by stray
      light effects within the MSG-1 satellite. I've just tried to recreate
      Ulrich's animation, and I can't see this effect so I either please post a
      copy of the animation or tell me where these effects are. Just to
      confirm: date: 2012-Feb-29, times 12:00-13:00 UTC?

      Cheers,
      David
      --
      SatSignal software - quality software written to your requirements
      Web: http://www.satsignal.eu
      Email: david-taylor@...
    • David J Taylor
      ... Ulrich, I don t think there are any polarising filters, but you could check on the SEVIRI specification. Regarding differences, rapid scan comes from
      Message 34 of 34 , Mar 3, 2012
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        > Seems I coined a new term there.. :)
        >
        > Interesting collection of speculations. Yes, Simon, I suspected a
        > special
        > geometrical coincidence of the sensor's opening, mechanical edges
        > fracturing some residual light and so forth, that reasoning coming from
        > a
        > photographical background.
        >
        > But then, more questions arise: Why only in the RSS frames, why not in
        > continuous frames there, Rob, you are right, the image is generated
        > sequentially - so the scene would look quite different when taken in a
        > synchronous shot. Wow. When will we see a weather satellite equipped
        > with
        > HD video? :)
        >
        > Simon, the same question arises for your explanation: Why only i a few,
        > non-consecutive frames? Undersampling effect, space- and timewise?
        >
        > BTW, does the sensing contain any kind of polarizing filters?
        >
        > Thanks for your contributions, anyway!
        >
        > Cheers,
        > U.

        Ulrich,

        I don't think there are any polarising filters, but you could check on the
        SEVIRI specification.

        Regarding differences, rapid scan comes from MSG-1, which is at a
        different orbital position (near 9.5E) to MSG-2 providing full scans, and
        MSG-1 has also suffered some impact damage (as I mentioned earlier). The
        position difference alone would equate to a timing difference in the
        observed effect.

        Cheers,
        David
        --
        SatSignal software - quality software written to your requirements
        Web: http://www.satsignal.eu
        Email: david-taylor@...
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