[cma-l] Propagation effects

Ian Hickling transplanfm at hotmail.com
Fri Jul 31 15:30:32 BST 2015




Yeah - understood - but as an engineer I prefer terms used to have the correct scientific implication.That's the whole essence of what we do after all.
Ian Hickling
Partner

Office: 01635 578435  (7am-11pm UK time)Carphone: 07530 980115 (only responds when driving)6 Horn Street, Compton, NEWBURY, RG20 6QS

Date: Fri, 31 Jul 2015 11:17:26 +0000
From: gordon.nicholas at btinternet.com
To: cma-l at mailman.commedia.org.uk
Subject: Re: [cma-l] Propagation effects

Ian..
The Hams refer to a "lift"  (in conditions) in the  sense that they can contact more stations than in "flat" conditions. They are just descriptive jargon and the wording is not  meant to have any scientific implication...Gordon

        From: Ian Hickling <transplanfm at hotmail.com>
 To: The Community Media Association Discussion List <cma-l at mailman.commedia.org.uk>; "vwradio at aol.com" <vwradio at aol.com>; tlr <tlr at gairloch.co.uk> 
 Sent: Friday, 31 July 2015, 11:41
 Subject: [cma-l] Propagation effects
   
There are four separate phenomena here and I've done a lot of work on this in the past - mainy with TV signals in Band I and III.The E layer (and also the even higher F layer) in the upper atmosphere become ionised by sunspots and other phenomena and act in a reflective/refractive manner.Sporadic (i e unpredictable) E propagation tends to last quite a long time - sometimes for days - and signals can be received very strongly over large distances.F-layer propagation is much rarer and can extend thousands of miles - such as conveying TV signals across the Atlantic.The signals bursts which flash and disappear in seconds are caused by meteor scatter - where a very short-lived ionised track is generated by a decaying meteor.It's possible then to receive a series of signals from different sources on the same frequency (or indeed television channel) within just a few seconds as the "mirror" moves across the sky.Tropospheric ducting (or "trop") is caused by temperature inversion.Static cold air over the Earth's  surface develops a warm upper layer from the Sun's heat and this acts like a tunnel, causing remote signals to curve back down to the surface.Hams often refer to all this erroneously as "lift".In fact - it's exactly the reverse - as it involves a downward rather than upward movement.Ian HicklingPartnerOffice: 01635 578435  (7am-11pm UK time)Carphone: 07530 980115 (only responds when driving)6 Horn Street, Compton, NEWBURY, RG20 6QS

From: tlr at gairloch.co.ukTo: cma-l at mailman.commedia.org.ukDate: Fri, 31 Jul 2015 10:16:49 +0100Subject: Re: [cma-l] Funky SX and the Lille tranmitter






Yes, as you say, it can work both ways - we 
also got a QSL request email from a DXer in Sweden who'd picked up our 
106.6 broadcasts.
 
Alex

  ----- Original Message ----- 
  From: 
  vwradio at aol.com 
  
  To: cma-l at mailman.commedia.org.uk 
  
  Sent: Friday, July 31, 2015 8:42 AM
  Subject: Re: [cma-l] Funky SX and the 
  Lille tranmitter
  When we get stations coming in strongly 
  from places like Spain - that's usually caused by sporadic-E. It's a 
  phenomenon where signals bounce off ionized clouds and can last minutes or 
  just seconds. Last month I heard a station from Morocco on FM stronger than 
  our local Heart in Dorset sitting in my car. This is different from the 
  tropospheric effect where French stations start coming in loud and clear. 
  Works both ways though - we got a report of being heard in Sweden on 92.3 via 
  sporadic E. 
  
  The wonders of radio propogation. Nothing you can do about it.
  
  Steve
   Company 
  registration: 04937308Telephone: Office 01202 820003 Studio 01202 
  820006Website: www.forestfm.co.uk 
  Facebook: ForestFM Verwood
  Twitter: @ForestFM
  
  Listen to us online 24 hours a day via the Tunein app or via 
  http://www.forestfm.co.uk/radioplayer/console/
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