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Fw: Scatter

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  • Randy Tipton
    Some good reading from Palle about Ionoscatter. ... From: Palle Preben-Hansen To: Randy Tipton Sent: Saturday, March 16,
    Message 1 of 1 , Mar 22, 2002
      Some good reading from Palle about Ionoscatter.

      ----- Original Message -----
      From: "Palle Preben-Hansen" <palle@...>
      To: "Randy Tipton" <wa5ufh@...>
      Sent: Saturday, March 16, 2002 18:02 PM
      Subject: Re: Scatter


      Hello Randy,

      Troposcatter and Ionoscatter are quite different. I hope you have read
      my
      text on troposcatter on www.oz1rh.com I have a 2.4 MB Word doc on
      Ionoscatter, would you like it on email? I will put it on
      www.oz1rh.com some
      day. Extract here:

      Conclusion
      1. Ionoscatter is a weak constant signal, stronger than eme, but
      weaker than
      anything else, IS is there 24H 365 days a year

      2. Ionoscatter is scatter in the lower ionosphere, D-layer at 65-90
      km

      3. Frequency dependence:
      - higher frequency = less scatter f**5!
      - higher frequency = less cosmic noise
      => optimum 40-60 MHz, e.g. 50 MHz amateur band
      - 144 MHz requires about 30 dB more than eme!
      - at 430 MHz even Areceibo (60 dB gain and 2 MW) can only detect the
      stronger day time scatter signal

      4. Diurnal variations
      - constant background signal from 85 km
      - strongest at noon mid path from 65-70 km (?)
      - phase measurement on VLF (17.8 kHz) shows D-layer height of 70 km at
      day
      time and 90 km at night
      - 11 years period? Research done 1950-56, just before sun spot maximum
      - sun eruption => stronger D-layer, more scatter and less cosmic noise
      due
      to increased absorption, then the higher frequencies (70 MHz) are
      better

      5. Distance
      < 1.000 km too steep scatter angle
      > 1.800-2.000 km no common volume
      => optimum around 1.200 km

      6. How to differentiate between IS, TS, MS, Es...
      - TS has zero radiation angle
      - MS only short lived, few sec to minutes but up to 40 dB increase in
      signal
      strength
      - Es often strong signal strength +40dB or more
      - other enhancements:
      - FAI is well known: only in the south, weak fluttery signal often
      after Es
      - PMSE, a kind of weak Es in the north

      7. Amateur possibilities compared to the military 20 dB antennas and
      40 kW
      system:
      - 1 kW - 16 dB
      - 12 dBd antenna - 8 dB
      - 50% reliability accepted + 28 dB => QSO's are possible!

      8. Enhancements of ionoscatter which may give increased scattering and
      perhaps make 144 MHz ionoscatter QSO's possible:
      - Es clouds which may have too low reflection frequency for the band
      used
      for ionoscatter
      - reminisce of meteor trails
      - other kinds of ionization's, like PSME
      - scattering in the F-layer
      - this would all be scattering in the ionosphere but is not the kind
      of
      ionoscatter available any time. If it gives you QSO's work first and
      worry
      about the causes of the ionization later.

      I have attached a smal draft from 1996 on ionoscatter.

      73, Palle, OZ1RH
      ----- Original Message -----
      From: "Randy Tipton" <wa5ufh@...>
      To: <oz1rh@...>
      Sent: Saturday, March 16, 2002 2:22 AM
      Subject: Scatter


      > So please can you tell me the difference between Troposcatter and
      > Ionoscatter? Are they the same?
      >
      > Randy Tipton (Tip)
      > WA5UFH EL19pa
      >
      > My Web Page
      > http://www.qsl.net/wa5ufh/
      > WSJT Group
      > http://groups.yahoo.com/group/wsjtgroup/?yguid=6309253
      >
      >
      > Scriptures I would like to share with you:
      > Heb 5:9; Acts 2:38; Rom 16:16: Eph 4: 1 - 7; John 17:20 - 23
      >
      >
      >
      >
      >
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