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Re: [perseus_SDR] Fw: Perseus remote Sound from Moscow rz3dvp missed ?

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  • Mauno Ritola
    Also AOR_Tokyo seems to have the new software, see below. No audio and S meter showing S9+70. Nico, are you still reading this list? ... Also AOR_Tokyo seems
    Message 1 of 48 , Jul 3, 2013
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      Also AOR_Tokyo seems to have the new software, see below. No audio and S meter showing S9+70.

      Nico, are you still reading this list?



      3.7.2013 12:29, Wolfgang Bueschel kirjoitti:
       

      > Re NEW Perseus Software v4.1a (19 June 2013 - 7.71 MB .zip file)"

      > We don't want to lose any remote rxs!

      In past 2 weeks it was missing the sound transmission from the remote
      station Moscow Nakhabino site of Yuri V. Maksimov RZ3DVP
      but now have been reactivated from past tonight.

      Thanks to Mauno for the effort.

      It was not on the attitudes of RZ3DVP Yuri V. Maksimov, but he had installed
      the Perseus new software version v4.1a
      which had now contained an interruption in the remote unit audio release.

      Now Yuri V. Maksimov RZ3DVP gone back to the previous version 4.0c !

      Is just the radio band observation on the remote Perseus unit in the Moscow
      region is very important and often completes the receptions in Western
      Europe installation gear from/over the NE/ME, Asian and Pacific bcast area.

      73 wb df5sx

      ----- Original Message -----
      From: "Wolfgang Bueschel"
      Sent: Wednesday, July 03, 2013
      Subject: Re: Perseus remote Sound from Moscow rz3dvp missed ?

      > Yes positive,
      > checked Moscow Nakhabino site of Yuri V. Maksimov RZ3DVP at 08 UT this
      > morning works perfect,
      > also now to check MW range on Moscow area morning, is exciting for German
      > ears so far ...
      >
      > Thanks for help on this Maksimov matter.
      > 73 wolfy
      >
      >
      > Sent: Wednesday, July 03, 2013 12:09 AM
      > Mauno Ritola kirjoitti
      > Subject: Re: Perseus remote Sound from Moscow rz3dvp missed ?
      >
      > He downgraded it back to 4.0c and now it works perfect. Please warn
      > people about this on perseus_SDR list. We don't want to lose any remote
      > rxs!
      >
      >
      > 2.7.2013 23:42, Mauno Ritola kirjoitti:
      >> Hi dear OM,
      >> I also remember checking last week, that there was no audio. Definitely
      >> something wrong with his settings.
      >> I have asked him via two email addresses, but he may have travelled for
      >> holiday, let's see.
      >>
      >> 73, Mauno
      >>
      >> 2.7.2013 18:26, Wolfgang Bueschel kirjoitti:
      >> Hi dear Mauno,
      >> is that a local fault on my Perseus remote receiving installation ?
      >>
      >> So 2 or more years I heard the remote Perseus unit sound from Moscow
      >> Nakhabino site of Yuri V. Maksimov RZ3DVP loud an clear, and also on
      >> extremely low noise floor.
      >>
      >>
      >> But some months ago, the RZ3DVP Perseus RX were SILENT a week or so,
      >>
      >> when came back on Perseus remote network 2-3 weeks later, the noise
      >> floor quality has been changed on negative manner,
      >>
      >> seemingly some neighbours bought some new electronic gear, PLC or
      >> PLASMA type TV - or Maksimov changed the Perseus location ?
      >>
      >> But now for some more days I experienced the SOUND missing on Perseus
      >> net from that Moscow location on my PC in TOTAL !

      >> BUT I CAN OPERATE ALL OTHER PERSEUS FEATURES; I SEE the Signal strenght
      >> meter twisting too etc. etc.
      >> only sound is missing here.
      >>
      >> Is that a local fault on my Perseus remote receiving ?
      >>
      >> 73 wolfy

      -----Ursprüngliche Nachricht-----
      Im Auftrag von Günter Lorenz
      Gesendet: Samstag, 22. Juni 2013 09:49
      Betreff: Perseus v4.1a

      http://microtelecom.it/perseus/software.html

      "NEW Perseus Software v4.1a (19 June 2013 - 7.71 MB .zip file)"

      Einzige (nicht unwesentliche) Änderung: USB 3.0 wird jetzt unterstützt.

      73,
      Günter


    • Leif Asbrink
      Hello Nico, ... I am afraid you apply a conventional model which is not applicable in the QRN-fighting context. Consider a sampling rate of 4 MHz. Apply a
      Message 48 of 48 , Jul 18, 2013
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        Hello Nico,

        > If one computes the number of taps of a FIR decimation
        > filter with a decent performance (say 0.1 dB in-band ripple
        > and 100 dB alias image rejection) he discover a simple
        > rule of thumb:
        >
        > N =(about) 4*D/(1-B/Fco)
        >
        > where:
        > N is the required decimation filter number of taps
        > D is the decimation factor
        > B/Fco is ratio between the desired output alias free bandwidth and the output sampling frequency.
        >
        > Since after filtering the decimator takes one output every D
        > input samples, the output impulse response is no more
        > than N/D samples long, that's to say:
        >
        > N/D =(about) 4/(1-B/Fco)
        >
        > Note that the length of the output impulse response
        > *does not* depend on the output sampling frequency, but just on the B/Fco ratio.
        > If such a ratio is high the output pulse can be quite long.

        I am afraid you apply a "conventional" model which is
        not applicable in the QRN-fighting context.

        Consider a sampling rate of 4 MHz.
        Apply a FIR filter that has say 0.1 dB in-band ripple
        and a -1 dB point at say 0.8 MHz. The -20 dB point should
        be at 2 MHz and the -100 dB point at 3.2 MHz. The alias-free
        range (-100 dB) would be +/- 0.8 MHz but a clever DSP software
        could compensate for the fall-off between say 0.8 and 1.6 MHz
        to provide a perfectly flat passband of 3.2 MHz or so. The alias
        suppression at the corner frequencies would be poor. Maybe 20 dB,
        but I do not think that would impair the noise-fighting.

        The useful bandwidth for receiving would be 1.6 MHz only and
        not any improvement over the 2 MHz sampling. The purpose of the
        faster sampling would only be to eliminate certain interference
        sources better.

        > In Perseus the decimation filter has been designed so that
        > the alias-free bandwidth is 80% the output sampling frequency
        > (1.6 MHz when the sampling rate is 2 MS/s) which is a good
        > compromise between the decimation filters complexity and
        > the efficiency of the digital signal processing made on the PC.
        > At such a B/Fco ratio you can expect that each output pulse
        > due to an istantaneous glitch at the receiver input is
        > approximately 4/(1-0.8) = 20 samples long whatever the
        > output sampling frequency is.
        Yes.

        > You can't really resolve it into a single pulse even if
        > the output sampling frequency were 40 MS/s. It will
        > always be 20 samples long.
        In Linrad, the PC software will take the fourier transform of the
        input data stream, divide it by the fourier transform of the
        impulse response of the hardware and multiply it by a "desired
        pulse response" This way the pulse length is made shorter than 20
        samples and at the same time the ~0.1 dB ripple is removed.

        The length of the pulse is determined by the "desired pulse response"
        which depends on the skirt steepness that the user has decided.
        The smart blanker knows the exact shape of the pulse and its length
        so it does not matter that the pulse is long in terms of samples.

        I am aware that very few operators use Linrad and that only
        a very small fraction of the users care to calibrate their
        systems properly. I have tried to explain the theory, but I
        do not think I have been sucessful at all. I am interested
        in static rain at high bandwidth because I have a feeling
        recordings would show a dramatic difference between the
        Linrad blanker and other blankers.

        > Of course 20 samples at 40 MS/s are a 0.5us interval,
        > which is a much shorter time interval than that obtained
        > if the sample rate were 2 MS/s but instead of increasing
        > the output sample rate one can obtain the same result
        > simply relaxing the B/Fco requirement.
        Yes:-)

        > If the B/Fco ratio were 60% instead of 80% the output
        > pulse lenght would be the half the original, if it were
        > 40% one third and if it were 20% one fourth of it, a
        > mere 5 samples interval (2.5us @ 2MS/s), which is even
        > the half of what one could obtain attempting to double
        > the output sampling frequency (and mantaining the
        > original 80% B/Fco ratio).
        > The penalty is that the the alias free bandwidth
        > is much less than the output sample rate...
        Yes:-) This is what I advocate. 4 MHz sampling and
        40% alias-free bandwidth. I also want the -10 dB point
        to be fairly high, maybe 80% of Nyquist.

        > but who cares if we would just be satisfied to (carefully)
        > clean-up a not-so-wide 200 kHz bandwidth out of a 2 MS/s
        > IQ stream?
        > And if it works, wouldn't it be better than obtaining the
        > same result using 4 MS/s maybe overloading a poor man CPU?
        As far as I undersdtand it is impossible to clean up a 200 kHz
        wide segment of a 2MS/s IQ stream if the (random) secondary
        pulses can not be resolved. From old experience as well as from
        the one and only wideband recording at my disposal a bandwidth
        of 1.6 MHz is marginal. It may or it may not work.

        > BTW, making a new 4MS/s DDC would not be impossible but
        > as I haven't implemented it yet I can't say that what
        > was initially conceived for a much smaller output sample
        > rate could sustain it (in 2008 I was even not sure that
        > the 2 MS/s rate could really work).
        Five years later it is very likely that a factor of two is OK:-)

        73

        Leif
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